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Papers by Wim Stalman

Journal of Clinical Epidemiology, 2007

Objective: Research in general practice has grown considerably over the past decades, but many pr... more Objective: Research in general practice has grown considerably over the past decades, but many projects face problems when recruiting patients. Lasagna's Law states that medical investigators overestimate the number of patients available for a research study. We aimed to assess factors related to success or failure of recruitment in general practice research. Study Design and Setting: Survey among investigators involved in primary care research in The Netherlands. Face-to-face interviews were held with investigators of 78 projects, assessing study design and fieldwork characteristics as well as success of patient recruitment. Results: Studies that focused on prevalent cases were more successful than studies that required incident cases. Studies in which the general practitioner (GP) had to be alert during consultations were less successful. When the GP or practice assistant was the first to inform the patient about the study, patient recruitment was less successful than when the patient received a letter by mail. There was a strong association among these three factors. Conclusion: Lasagna's Law also holds in Dutch primary care research: many studies face recruitment problems. Awareness of study characteristics affecting participation of GPs and patients may help investigators to improve their study design.

Journal of Clinical Epidemiology, 2004

Objective: To assess the association of decline in physical functioning with number of chronic di... more Objective: To assess the association of decline in physical functioning with number of chronic diseases and with specific comorbidity in different index diseases. Methods: A longitudinal design was employed using data from 2,497 older adults participating in the Longitudinal Aging Study Amsterdam. Logistic regression analyses were used to determine influence of chronic diseases on change in physical functioning, operationalized using the Edwards-Nunnally index. Results: Decline in physical functioning was associated with number of chronic diseases (adjusted ORs from 1.58 for 1, to 4.05 for у3 diseases). Comorbidity of chronic nonspecific lung disease and malignancies had the strongest exacerbating influence on decline. An exacerbating effect was also found for arthritis in subjects with diabetes or malignancies and for stroke in subjects with chronic nonspecific lung disease or malignancies. A weaker effect than expected was observed for diabetes in subjects with stroke, malignancies, cardiac disease, or peripheral atherosclerosis. Conclusion: Comorbidities involving chronic diseases that share etiologic factors or pathophysiologic mechanisms appear to have a weaker negative influence on decline in physical functioning than expected. Results indicate that combinations of diseases that both influence physical functioning, but through different mechanisms (locomotor symptoms vs. decreased endurance capacity) may be more detrimental than other combinations.

Journal of Affective Disorders, 2008

Background: Old people (75+) are underrepresented in studies on the prevalence of and risk factor... more Background: Old people (75+) are underrepresented in studies on the prevalence of and risk factors for depression while the number of elderly people suffering from this mood disorder may be considerably higher than previously assumed. The roleif anyof age and gender in 'Geriatric Depression' is still unclear. Methods: In this community-based study, prevalence of depressive symptomatology and risk indicators were assessed in 2850 participants aged 75 years or more. A clinically relevant level of depressive symptoms was defined as a score of ≥ 16 on the Centre for Epidemiologic Studies Depression scale (CES-D). Demographic data and questions related to physical and psychological health were recorded. Simple and multiple logistic regression techniques were used to determine the risk indicators (Odds Ratios, OR, with 95% confidence intervals, CI) with apparent importance to this population. Results: The prevalence of depressive symptoms was assessed to be 31.1%. This is considerably higher than what has been found in younger elderly samples. The bivariate age effect was OR 1.05 (95% CI = 1.03 to 1.07). Controlling for confounding, the effect of gender and age on depressive symptoms disappeared. Conclusions: Depressive symptoms are highly prevalent in the elderly population and increase with age. This increase seems to be attributable to age-related changes in risk factors rather than to ageing itself. With regard to the risk factors found, attention should perhaps be paid to functional disability, loneliness and apprehensiveness for falling since these risk indicators are amenable for improvement.

Journal of Affective Disorders, 2008

Background: Minor depression is common in primary care and associated with increased health care ... more Background: Minor depression is common in primary care and associated with increased health care costs. Many mildly depressed patients are prescribed antidepressants, although there is insufficient information on the cost-effectiveness of antidepressants for these patients. The objective of this study was to evaluate whether usual care without antidepressants is equivalent to (i.e. as effective as and as expensive as) usual care with antidepressants in patients with minor or mild-major depression. Methods: Severity of depression was measured using the Montgomery Asberg Depression Rating Scale (MADRS) and qualityadjusted life-years (QALYs) using the EuroQol. Resource use was measured from a societal perspective using cost diaries. Bootstrapping was used to analyze the cost-effectiveness data. Results: Equivalence could not be shown for improvement in MADRS score or QALYs gained at 52 weeks. The mean (95% CI) difference in total costs between usual care without antidepressants and usual care with antidepressants was −€751 (−3601; 1522). Using an equivalence margin of €500 equivalence in costs could not be shown. In the cost-effectiveness analyses equivalence also could not be shown. Limitations: This study was underpowered for economic outcomes. Another limitation was the loss-to-follow-up. Conclusions: Although equivalence could not be shown in the costs and cost-effectiveness analyses, 95% confidence intervals also did not show that usual care without antidepressants was vastly superior or inferior to usual care with antidepressants. Therefore, we recommend general practitioners to show restraint when prescribing antidepressants to mildly depressed patients.

Journal of Affective Disorders, 2010

Background: Stress-related mental health problems negatively impact quality of life and productiv... more Background: Stress-related mental health problems negatively impact quality of life and productivity. Worldwide, treatment is often sought in primary care. Our objective was to determine whether a general practitioner-based minimal intervention for workers with stressrelated sick leave (MISS) was cost-effective compared to usual care (UC). Methods: We conducted an economic evaluation from a societal perspective. Quality-adjusted life years (QALYs) and resource use were measured by the EuroQol and cost diaries, respectively. Uncertainty was estimated by 95% confidence intervals, cost-effectiveness planes and acceptability curves. Sensitivity analyses and ancillary analyses based on preplanned subgroups were performed. Results: No statistically significant differences in costs or QALYs were observed. The mean incremental cost per QALY was −€7356 and located in the southeast quadrant of the costeffectiveness plane, whereby the intervention was slightly more effective and less costly. For willingness-to-pay (λ) thresholds from €0 to €100,000, the probability of MISS being cost-effective was 0.58-0.90. For the preplanned subgroup of patients diagnosed with stress-related mental disorders, the incremental ratio was −€28,278, again in the southeast quadrant. Corresponding probabilities were 0.92 or greater. Limitations: Non-significant findings may be related to poor implementation of the MISS intervention and low power. Also, work-presenteeism and unpaid labor were not measured. Conclusions: The minimal intervention was not cost-effective compared to usual care for a heterogeneous patient population. Therefore, we do not recommend widespread implementation. However, the intervention may be cost-effective for the subgroup stress-related mental disorders. This finding should be confirmed before implementation for this subgroup is considered.

International Journal of Geriatric Psychiatry, 2007

Objective To examine whether a new screening method that identified patients with cognitive impai... more Objective To examine whether a new screening method that identified patients with cognitive impairment who needed further examination on the presence of dementia yielded patients who were not detected by their general practitioner (GP), and to identify factors associated with GPs' awareness of patients identified by the screening. Methods Cross-sectional comparison between two methods used to identify dementia symptoms: (1) usual identification of dementia by GPs; (2) a two-stage screening to identify cognitive impairment. The two methods were implemented on the same older general practice population. The study was set in primary care practices in the Netherlands. The participants were 44 GPs and 2,101 general practice patients aged 75þ who lived at home. The following measurements were used: (1) yield of the screening; (2) determinants of GPs' awareness of patients identified by the screening. Results The two-stage screening yielded 117 patients with cognitive impairment who needed further examination; in most cases (n ¼ 82, 70.1%) their GP was unaware of the symptoms. Among patients identified by the screening, GPs' awareness was associated with co-morbidity of chronic diseases [odds ratio (OR) ¼ 3.19; 95% Confidence Interval (CI) ¼ 1.25 to 8.15], depressive symptoms (OR ¼ 0.41; 95% CI ¼ 0.17 to 0.99), and cognitive functioning (per point on the MMSE, OR ¼ 0.88; 95% CI ¼ 0.79 to 0.98). Conclusion A two-stage screening method and increased alertness for cognitive impairment and dementia among patients with depressive symptoms may improve detection rate of dementia in general practice.

International Journal of Geriatric Psychiatry, 2007

several interventions often attempted in such cases was demonstrated. The ineffectiveness of medi... more several interventions often attempted in such cases was demonstrated. The ineffectiveness of medication trials was due to noncompliance. Despite the lack of frank dementia and relatively mild (for age) cognitive deficits, this patient's safe independent functioning was severely compromised and her functional capacities had declined. She needs significant supervision but was resistant and openly hostile to any limitations or assistance. It may be that some of the resistance to treatment could be alleviated by limiting her health provider contact to a single primary health care worker (if not medically contraindicated). This contact may draw the patient out from her socially isolated tendencies while still providing appropriate medical care (Reyes-Ortiz, 2001). Involvement in an adult daycare program may also provide similar benefits (Reyes-Ortiz, 2001). Behavioral change and functional decline are the final common outcome of myriad clinical conditions confronted in the care of elderly patients. Careful differential diagnosis is critical to appropriate treatment selection, particularly with ever increasing pharmacological options. This case demonstrates the challenges created by psychiatric illness, and particularly Axis II psychopathology, in the elderly and emphasizes the value of psychometric testing to the diagnostic process.

Gastroenterology, 2001

ABSTRACT To facilitate the development of clinical guidelines and to direct future irritable bowe... more ABSTRACT To facilitate the development of clinical guidelines and to direct future irritable bowel syndrome (IBS) research, insight into the perceptions of patients and general practitioners (GPs) regarding IBS is required. To compare patients' and GPs' views on the symptomatology, etiology and treatment of IBS. One hundred forty-two IBS patients and 100 GPs were requested to complete a structured questionnaire. The response rates of the patients and GPs were 80% and 47%, respectively. Abdominal pain and bloating were considered to be the most bothersome symptoms in IBS, by both patients and GPs. Although all patients were diagnosed by their GP as having IBS, and 62% met the Manning criteria, only 18% fulfilled the Rome II criteria for IBS. Patients consider food intolerance and GPs regard lack of fibre as the main etiologic dietary factor. Many IBS patients expect a diagnostic work-up, but GPs generally restrict this to elderly patients. GPs start IBS management with dietary advice (94%), counselling (77%) and drug therapy (55%). Patients expect reassurance (47%) and drug treatment (37%), but dietary interventions are less appreciated (9%). Patients and GPs have different perceptions of the efficacy of diagnostic and dietary interventions in IBS. GPs should explore the patients expectations and incorporate these in their approach to IBS patients.

Family Practice, 2003

Background. Antithrombotic treatment in atrial fibrillation should be guided by the risk of throm... more Background. Antithrombotic treatment in atrial fibrillation should be guided by the risk of thromboembolic events. Although practice studies have shown underutilization of antithrombotics, it is not clear whether physicians make use of thromboembolic risk stratification in their treatment decisions, as recommended in current guidelines. Objective. The aim of the present study was to assess which clinical determinants influence coumarin and aspirin prescription in patients with atrial fibrillation in primary care. Methods. In a cross-sectional study of 15 computerized general practices covering 38 000 patients in The Netherlands, we identified patients with atrial fibrillation using several search algorithms. Determinants of antithrombotic therapy were assessed using polytomous logistic regression analysis. Results. A total of 247 patients with atrial fibrillation were identified among 10 335 patients aged 55 years or over (prevalence 2.4%). Mean age was 77 years (range 55-95); 51% were male. Overall, 52% of the patients used coumarin and 27% used aspirin. About 50% of patients were also treated by a cardiologist. Referred patients were prescribed coumarin more often (63% versus 35%, P Ͻ 0.001). Prior stroke/transient ischaemic attack or systemic embolism [adjusted odds ratio (OR) 5.3, 95% confidence interval (CI) 1.1-24.8], and chronic heart failure (adjusted OR 2.1, 95% CI 0.8-5.1) were independent determinants for coumarin prescription. These associations were less strong for aspirin prescription. However, other established risk factors for future thromboembolic events, such as hypertension and diabetes mellitus, did not lead to higher prescription rates. In contrast, several factors not associated with thromboembolic events, such as chronic (versus paroxysmal) atrial fibrillation (adjusted OR 3.7, 95% CI 1.7-8.2) and longstanding (versus recent) diagnosis (adjusted OR 2.2, 95% CI 1.1-4.5), were also associated with higher coumarin prescription. Conclusion. These results illustrate that physicians' decisions about initiating antithrombotic therapy in atrial fibrillation are not evidence based. They are guided partly by thromboembolic risk stratification, but also by factors insignificant for thromboembolic risk.

Family Practice, 1997

To assess the methodological quality of double-blind placebo-controlled randomised clinical trial... more To assess the methodological quality of double-blind placebo-controlled randomised clinical trials (RCTs), regarding the effectiveness of antibiotic treatment in acute maxillary sinusitis in adults. Searching MEDLINE was searched from January 1966 to July 1996 using the keywords 'Respiratory Tract Infection' OR 'Sinusitis' AND 'Antibiotics'. In addition, the bibliographies of relevant articles were reviewed and the Cochrane Collaboration was consulted. The search strategy was limited to Dutch, English, French, German and Scandinavian studies.

Family Practice, 2005

Background. Benzodiazepines are frequently prescribed for sleep disturbances. However, benzodiaze... more Background. Benzodiazepines are frequently prescribed for sleep disturbances. However, benzodiazepines are associated with side effects, and may be ineffective when used for a prolonged period of time. Objectives. To investigate for individual patients whether placebo was as effective as temazepam, or whether 10 mg was as effective as 20 mg temazepam, and whether these results influenced their future temazepam use. Methods. A series of randomized double-blind N-of-1 trials were conducted in general practices in The Netherlands for patients who were using temazepam regularly. Each patient received five pairs of treatments consisting of one week of temazepam (10 or 20 mg) and one week of the control intervention (placebo or 10 mg temazepam). Per pair, the sequence of treatments was randomized. Main outcome measures were: time to fall asleep, and the individual main complaint. Results. Twelve out of 15 patients completed their trial. In three patients there was no difference, in five a large difference, and in four a small difference in favour of temazepam. At follow-up, seven patients had stopped or reduced their temazepam use. Conclusion. The results regarding the efficacy of temazepam varied across patients. N-of-1 trials seem to be valuable in patients who are motivated to stop or reduce their temazepam use. They clearly demonstrate the efficacy of temazepam, and may give patients additional confidence to discontinue regular hypnotic use. The value of N-of-1 trials for patients who are less motivated is unclear, as the size of treatment effect does not seem to influence future hypnotic use.

Family Practice, 2004

Background. Physical activity promotion in general practice is advocated though not incorporated ... more Background. Physical activity promotion in general practice is advocated though not incorporated into daily practice. Several barriers must be overcome to develop a feasible and acceptable programme. Objective. The aim of this study was to conduct a process evaluation of a physical activity promotion programme in general practice (PACE), in which patients visited their provider (GP or practice nurse) twice. Methods. Process evaluation was conducted by means of telephone-administered, semistructured interviews with providers and practice assistants. The main topics of the interviews were overall impression of PACE, PACE training, content and usability of the intervention materials, counselling, implementation of the intervention, and opportunities for future use. Results. In the 15 participating general practices, a total of 17 providers and 12 practice assistants were interviewed. The overall impression of the PACE programme was positive. Most providers experienced the provided material and training as helpful. Some problems concerning the number of forms used and patients having difficulties completing the forms were mentioned. Most providers (70.6%) spend 10 min or more discussing PACE during the first consultation. The second consultation mostly was completed within 10 min. Patients overestimating their level of physical activity was mentioned as the main barrier in providing the counselling. PACE was evaluated as suitable for implementation in Dutch general practice, and 60% of the providers actually intended using PACE in the future. Conclusion. The PACE programme was evaluated as being both acceptable and feasible in a selection of Dutch general practices. Positive adaptations will be made in order to implement PACE successfully in general practice at a wider scale.

Family Practice, 2002

Background. Postherpetic neuralgia (PHN) is a frequent complication of herpes zoster (HZ). Treatm... more Background. Postherpetic neuralgia (PHN) is a frequent complication of herpes zoster (HZ). Treatment results of this severe and long-lasting pain syndrome are often disappointing. From the point of view of possible prevention and early treatment, it is important to identify HZ patients who have an increased risk of developing PHN. Objectives. Our goals were to determine the incidence of HZ and PHN in a primary care population and to identify risk indicators for the occurrence of PHN. Methods. A search for HZ and PHN was conducted in a general practice research database, comprising 22 general practices and representing 49 000 people, over a 5-year period. Potential risk indicators were analysed using multivariate logistic regression. Results. A total of 837 patients had been diagnosed with HZ [incidence 3.4/1000 patients/year, 95% confidence interval (CI) 2.9-3.9]. The risk of developing PHN 1 month after the start of the zoster rash was 6.5% (95% CI 4.9-8.3). This risk was 11.7% (95% CI 8.5-14.9) for patients aged у55 years. Independent risk indicators for the occurrence of PHN were age [55-74 years, adjusted odds ratio (OR) 4.2, 95% CI 1.8-9.7; Ͼ75 years, OR 10.7, 95% CI 4.6-25.1] and ophthalmic localization (OR 2.3, 95% CI 1.0-4.6). Conclusions. The risk of developing PHN increases with age. Preventive strategies should focus on patients with herpes zoster aged Ͼ55 years and with ophthalmic localization.

Family Practice, 2007

Background. Earlier reports suggest limited clinical reasoning and substantial uncertainty of GPs... more Background. Earlier reports suggest limited clinical reasoning and substantial uncertainty of GPs in assessing patients suspected of dementia. Objective. To explore the predictors of GPs to decide on the presence and absence of dementia as well as the predictors of diagnostic confidence of GPs. Design. An observational study was set up among 107 patients of 64 GPs. The GPs were instructed to use the Dutch national dementia guideline on consecutive patients newly suspected of dementia and to register their assessment on a detailed form. The predictors of the presence and absence of dementia according to the GPs and their diagnostic confidence were explored by logistic regression analyses. Main outcome measures. Dependent variables: (i) presence and absence of dementia according to GPs and (ii) diagnostic confidence. Independent variables: clinical (cognitive, behavioural, somatic, functional), applications of recommendations, patient related and GP related. Results. Dementia was diagnosed in 67% of the suspected patients. The presence of dementia according to the GPs was positively associated with observed impairment of the higher cognitive functions, absence of depression and female gender of patients. The GPs expressed diagnostic confidence in 58% of the cases. This was positively associated with application of recommendations, ADL dependency, longer duration, informant availability, restless behaviour and a patient's female gender. Use of the Mini Mental Status Examination was not associated with confidence. Conclusions. GPs seem to base the diagnosis of dementia on rational grounds. Application of the dementia guideline's recommendations may contribute to more diagnostic confidence.

European Spine Journal, 2007

An intervention that can prevent low back pain (LBP) becoming chronic, may not only prevent great... more An intervention that can prevent low back pain (LBP) becoming chronic, may not only prevent great discomfort for patients, but also save substantial costs for the society. Psychosocial factors appear to be of importance in the transition of acute to chronic LBP. The aim of this study was to compare the cost-effectiveness of an intervention aimed at psychosocial factors to usual care in patients with (sub)acute LBP. The study design was an economic evaluation alongside a cluster-randomized controlled trial, conducted from a societal perspective with a follow-up of 1 year. Sixty general practitioners in 41 general practices recruited 314 patients with non-specific LBP of less than 12 weeks' duration. General practitioners in the minimal intervention strategy (MIS) group explored and discussed psychosocial prognostic factors. Usual care (UC) was not protocolized. Clinical outcomes were functional disability (Roland-Morris Disability Questionnaire), perceived recovery and health-related quality of life (Eu-roQol). Cost data consisted of direct and indirect costs and were measured by patient cost diaries and general practitioner registration forms. Complete cost data were available for 80% of the patients. Differences in clinical outcomes between both the groups were small and not statistically significant. Differences in cost data were in favor of MIS. However, the complete case analysis and the sensitivity analyses with imputed cost data were inconsistent with regard to the statistical significance of this difference in cost data. This study presents conflicting points of view regarding the cost-effectiveness of MIS. We conclude that (Dutch) general practitioners, as yet, should not replace their usual care by this new intervention.

The European Journal of Public Health, 2009

Background: The primary care evaluation of mental disorders (PRIME-MD) can be seen as characteris... more Background: The primary care evaluation of mental disorders (PRIME-MD) can be seen as characteristic for successive refinements of criteria and structured interview techniques for diagnosing psychiatric disorders in primary care. It is one of the most widely used instruments, but there is no evidence to support its test-retest reliability. Methods: With 1-week intervals between interviews, a test-retest study of the PRIME-MD was conducted in a general practice population of 100 distressed patients (20-to 60-years old) who were on sick leave. Results: Almost everyone (89%) received one or more diagnoses at both measurements, and there was fair total agreement (= 0.27). The best agreement was found for more severe threshold disorders [major depressive disorder (= 0.58), dysthymia (= 0.57), and generalized anxiety disorder (= 0.59)], while we found indefinite results for the sub-threshold disorders [anxiety disorder not otherwise specified (NOS) (=.30), minor depressive disorder (= À0.03), and somatoform disorder NOS (= 0.11)]. Conclusion: The PRIME-MD is one of the few instruments in primary care that actually diagnoses specific mental disorders according to the DSM criteria. However, there was a failure to adequately classify sub-threshold disorders. Mental disorders, as seen in primary care, encompass important specific symptoms and clinical syndromes that vary in duration and severity over time, but they also encompass an admixture of somatic and psychological symptoms that do not match current diagnostic systems. This most likely resulted in methodological uncertainty about the level of agreement. Diagnostic criteria in psychiatry need to be operationalized for use in primary care and require further evaluation.

Epidemiology and Infection, 2002

Influenza immunization rates among young asthmatics remain unsatisfactory due to persistent conce... more Influenza immunization rates among young asthmatics remain unsatisfactory due to persistent concern about the impact of influenza and the benefits of the vaccine. We assessed the effectiveness of the conventional inactivated trivalent sub-unit influenza vaccine in reducing acute respiratory disease in asthmatic children. We conducted a two-season retrospective cohort study covering the 1995–6 and 1996–7 influenza outbreaks in 22 computerized primary care practices in the Netherlands. In total, 349 patients aged between 0 and 12 years meeting clinical asthma-criteria were included; 14 children were lost to follow-up in the second season. The occurrence of physician-diagnosed acute respiratory disease episodes including influenza-like illness, pneumonia, bronchitis, bronchiolitis, asthma exacerbation and acute otitis media in vaccinated and unvaccinated children were compared after adjustments for age, prior health care and medication use. The occurrence of acute respiratory disease i...

Diabetes Care, 2005

Potential role of glial cell linederived neurotrophic factor receptors in Mü ller glial cells dur... more Potential role of glial cell linederived neurotrophic factor receptors in Mü ller glial cells during light-induced retinal degeneration.

Clinical Practice and Epidemiology in Mental Health, 2007

Background: The Sense of Competence Questionnaire (SCQ) was originally developed for informal car... more Background: The Sense of Competence Questionnaire (SCQ) was originally developed for informal caregivers of patients with diagnosed dementia. In order to study the validity and usefulness of the SCQ when applied to informal caregivers of older adults with dementia symptoms (i.e. cognitive impairment, pre-diagnostic dementia or dementia in its early stages), we investigated the construct validity, feasibility, subscales, homogeneity, and floor and ceiling effects in this new target population. Methods: A psychometric evaluation was performed among 99 informal caregivers. To investigate construct validity, hypotheses were tested, concerning the association between sense of competence and burden, mental quality of life, depressive symptoms, and mastery. To investigate feasibility, response rate and the proportion of missing data were explored for each item. An exploratory principal component analysis was used to investigate whether the SCQ comprises the three subscales established in previous studies. Homogeneity was assessed for each subscale with Cronbach's α and item-total correlations. Floor and ceiling effects were explored. Results: Most hypotheses on construct validity were rejected. Only the subscale 'consequences of involvement in care' was found to be partly valid. Feasibility: 93 out of 99 persons completed the SCQ. The proportion of unanswered items per item ranged from 0-3%. Subscales: the SCQ comprises the three expected subscales. Homogeneity: Cronbach's alpha and item-total correlations of the three subscales were satisfactory. A ceiling effect occurred on the subscale 'satisfaction with the care recipient'. Conclusion: The three subscales of the SCQ showed good homogeneity and feasibility, but their validity is insufficient: only the subscale 'consequences of involvement' was found to be partly valid. The two other subscales might not be relevant yet for the new target population, since many of the items on these scales

Journal of Clinical Epidemiology, 2007

Objective: Research in general practice has grown considerably over the past decades, but many pr... more Objective: Research in general practice has grown considerably over the past decades, but many projects face problems when recruiting patients. Lasagna's Law states that medical investigators overestimate the number of patients available for a research study. We aimed to assess factors related to success or failure of recruitment in general practice research. Study Design and Setting: Survey among investigators involved in primary care research in The Netherlands. Face-to-face interviews were held with investigators of 78 projects, assessing study design and fieldwork characteristics as well as success of patient recruitment. Results: Studies that focused on prevalent cases were more successful than studies that required incident cases. Studies in which the general practitioner (GP) had to be alert during consultations were less successful. When the GP or practice assistant was the first to inform the patient about the study, patient recruitment was less successful than when the patient received a letter by mail. There was a strong association among these three factors. Conclusion: Lasagna's Law also holds in Dutch primary care research: many studies face recruitment problems. Awareness of study characteristics affecting participation of GPs and patients may help investigators to improve their study design.

Journal of Clinical Epidemiology, 2004

Objective: To assess the association of decline in physical functioning with number of chronic di... more Objective: To assess the association of decline in physical functioning with number of chronic diseases and with specific comorbidity in different index diseases. Methods: A longitudinal design was employed using data from 2,497 older adults participating in the Longitudinal Aging Study Amsterdam. Logistic regression analyses were used to determine influence of chronic diseases on change in physical functioning, operationalized using the Edwards-Nunnally index. Results: Decline in physical functioning was associated with number of chronic diseases (adjusted ORs from 1.58 for 1, to 4.05 for у3 diseases). Comorbidity of chronic nonspecific lung disease and malignancies had the strongest exacerbating influence on decline. An exacerbating effect was also found for arthritis in subjects with diabetes or malignancies and for stroke in subjects with chronic nonspecific lung disease or malignancies. A weaker effect than expected was observed for diabetes in subjects with stroke, malignancies, cardiac disease, or peripheral atherosclerosis. Conclusion: Comorbidities involving chronic diseases that share etiologic factors or pathophysiologic mechanisms appear to have a weaker negative influence on decline in physical functioning than expected. Results indicate that combinations of diseases that both influence physical functioning, but through different mechanisms (locomotor symptoms vs. decreased endurance capacity) may be more detrimental than other combinations.

Journal of Affective Disorders, 2008

Background: Old people (75+) are underrepresented in studies on the prevalence of and risk factor... more Background: Old people (75+) are underrepresented in studies on the prevalence of and risk factors for depression while the number of elderly people suffering from this mood disorder may be considerably higher than previously assumed. The roleif anyof age and gender in 'Geriatric Depression' is still unclear. Methods: In this community-based study, prevalence of depressive symptomatology and risk indicators were assessed in 2850 participants aged 75 years or more. A clinically relevant level of depressive symptoms was defined as a score of ≥ 16 on the Centre for Epidemiologic Studies Depression scale (CES-D). Demographic data and questions related to physical and psychological health were recorded. Simple and multiple logistic regression techniques were used to determine the risk indicators (Odds Ratios, OR, with 95% confidence intervals, CI) with apparent importance to this population. Results: The prevalence of depressive symptoms was assessed to be 31.1%. This is considerably higher than what has been found in younger elderly samples. The bivariate age effect was OR 1.05 (95% CI = 1.03 to 1.07). Controlling for confounding, the effect of gender and age on depressive symptoms disappeared. Conclusions: Depressive symptoms are highly prevalent in the elderly population and increase with age. This increase seems to be attributable to age-related changes in risk factors rather than to ageing itself. With regard to the risk factors found, attention should perhaps be paid to functional disability, loneliness and apprehensiveness for falling since these risk indicators are amenable for improvement.

Journal of Affective Disorders, 2008

Background: Minor depression is common in primary care and associated with increased health care ... more Background: Minor depression is common in primary care and associated with increased health care costs. Many mildly depressed patients are prescribed antidepressants, although there is insufficient information on the cost-effectiveness of antidepressants for these patients. The objective of this study was to evaluate whether usual care without antidepressants is equivalent to (i.e. as effective as and as expensive as) usual care with antidepressants in patients with minor or mild-major depression. Methods: Severity of depression was measured using the Montgomery Asberg Depression Rating Scale (MADRS) and qualityadjusted life-years (QALYs) using the EuroQol. Resource use was measured from a societal perspective using cost diaries. Bootstrapping was used to analyze the cost-effectiveness data. Results: Equivalence could not be shown for improvement in MADRS score or QALYs gained at 52 weeks. The mean (95% CI) difference in total costs between usual care without antidepressants and usual care with antidepressants was −€751 (−3601; 1522). Using an equivalence margin of €500 equivalence in costs could not be shown. In the cost-effectiveness analyses equivalence also could not be shown. Limitations: This study was underpowered for economic outcomes. Another limitation was the loss-to-follow-up. Conclusions: Although equivalence could not be shown in the costs and cost-effectiveness analyses, 95% confidence intervals also did not show that usual care without antidepressants was vastly superior or inferior to usual care with antidepressants. Therefore, we recommend general practitioners to show restraint when prescribing antidepressants to mildly depressed patients.

Journal of Affective Disorders, 2010

Background: Stress-related mental health problems negatively impact quality of life and productiv... more Background: Stress-related mental health problems negatively impact quality of life and productivity. Worldwide, treatment is often sought in primary care. Our objective was to determine whether a general practitioner-based minimal intervention for workers with stressrelated sick leave (MISS) was cost-effective compared to usual care (UC). Methods: We conducted an economic evaluation from a societal perspective. Quality-adjusted life years (QALYs) and resource use were measured by the EuroQol and cost diaries, respectively. Uncertainty was estimated by 95% confidence intervals, cost-effectiveness planes and acceptability curves. Sensitivity analyses and ancillary analyses based on preplanned subgroups were performed. Results: No statistically significant differences in costs or QALYs were observed. The mean incremental cost per QALY was −€7356 and located in the southeast quadrant of the costeffectiveness plane, whereby the intervention was slightly more effective and less costly. For willingness-to-pay (λ) thresholds from €0 to €100,000, the probability of MISS being cost-effective was 0.58-0.90. For the preplanned subgroup of patients diagnosed with stress-related mental disorders, the incremental ratio was −€28,278, again in the southeast quadrant. Corresponding probabilities were 0.92 or greater. Limitations: Non-significant findings may be related to poor implementation of the MISS intervention and low power. Also, work-presenteeism and unpaid labor were not measured. Conclusions: The minimal intervention was not cost-effective compared to usual care for a heterogeneous patient population. Therefore, we do not recommend widespread implementation. However, the intervention may be cost-effective for the subgroup stress-related mental disorders. This finding should be confirmed before implementation for this subgroup is considered.

International Journal of Geriatric Psychiatry, 2007

Objective To examine whether a new screening method that identified patients with cognitive impai... more Objective To examine whether a new screening method that identified patients with cognitive impairment who needed further examination on the presence of dementia yielded patients who were not detected by their general practitioner (GP), and to identify factors associated with GPs' awareness of patients identified by the screening. Methods Cross-sectional comparison between two methods used to identify dementia symptoms: (1) usual identification of dementia by GPs; (2) a two-stage screening to identify cognitive impairment. The two methods were implemented on the same older general practice population. The study was set in primary care practices in the Netherlands. The participants were 44 GPs and 2,101 general practice patients aged 75þ who lived at home. The following measurements were used: (1) yield of the screening; (2) determinants of GPs' awareness of patients identified by the screening. Results The two-stage screening yielded 117 patients with cognitive impairment who needed further examination; in most cases (n ¼ 82, 70.1%) their GP was unaware of the symptoms. Among patients identified by the screening, GPs' awareness was associated with co-morbidity of chronic diseases [odds ratio (OR) ¼ 3.19; 95% Confidence Interval (CI) ¼ 1.25 to 8.15], depressive symptoms (OR ¼ 0.41; 95% CI ¼ 0.17 to 0.99), and cognitive functioning (per point on the MMSE, OR ¼ 0.88; 95% CI ¼ 0.79 to 0.98). Conclusion A two-stage screening method and increased alertness for cognitive impairment and dementia among patients with depressive symptoms may improve detection rate of dementia in general practice.

International Journal of Geriatric Psychiatry, 2007

several interventions often attempted in such cases was demonstrated. The ineffectiveness of medi... more several interventions often attempted in such cases was demonstrated. The ineffectiveness of medication trials was due to noncompliance. Despite the lack of frank dementia and relatively mild (for age) cognitive deficits, this patient's safe independent functioning was severely compromised and her functional capacities had declined. She needs significant supervision but was resistant and openly hostile to any limitations or assistance. It may be that some of the resistance to treatment could be alleviated by limiting her health provider contact to a single primary health care worker (if not medically contraindicated). This contact may draw the patient out from her socially isolated tendencies while still providing appropriate medical care (Reyes-Ortiz, 2001). Involvement in an adult daycare program may also provide similar benefits (Reyes-Ortiz, 2001). Behavioral change and functional decline are the final common outcome of myriad clinical conditions confronted in the care of elderly patients. Careful differential diagnosis is critical to appropriate treatment selection, particularly with ever increasing pharmacological options. This case demonstrates the challenges created by psychiatric illness, and particularly Axis II psychopathology, in the elderly and emphasizes the value of psychometric testing to the diagnostic process.

Gastroenterology, 2001

ABSTRACT To facilitate the development of clinical guidelines and to direct future irritable bowe... more ABSTRACT To facilitate the development of clinical guidelines and to direct future irritable bowel syndrome (IBS) research, insight into the perceptions of patients and general practitioners (GPs) regarding IBS is required. To compare patients' and GPs' views on the symptomatology, etiology and treatment of IBS. One hundred forty-two IBS patients and 100 GPs were requested to complete a structured questionnaire. The response rates of the patients and GPs were 80% and 47%, respectively. Abdominal pain and bloating were considered to be the most bothersome symptoms in IBS, by both patients and GPs. Although all patients were diagnosed by their GP as having IBS, and 62% met the Manning criteria, only 18% fulfilled the Rome II criteria for IBS. Patients consider food intolerance and GPs regard lack of fibre as the main etiologic dietary factor. Many IBS patients expect a diagnostic work-up, but GPs generally restrict this to elderly patients. GPs start IBS management with dietary advice (94%), counselling (77%) and drug therapy (55%). Patients expect reassurance (47%) and drug treatment (37%), but dietary interventions are less appreciated (9%). Patients and GPs have different perceptions of the efficacy of diagnostic and dietary interventions in IBS. GPs should explore the patients expectations and incorporate these in their approach to IBS patients.

Family Practice, 2003

Background. Antithrombotic treatment in atrial fibrillation should be guided by the risk of throm... more Background. Antithrombotic treatment in atrial fibrillation should be guided by the risk of thromboembolic events. Although practice studies have shown underutilization of antithrombotics, it is not clear whether physicians make use of thromboembolic risk stratification in their treatment decisions, as recommended in current guidelines. Objective. The aim of the present study was to assess which clinical determinants influence coumarin and aspirin prescription in patients with atrial fibrillation in primary care. Methods. In a cross-sectional study of 15 computerized general practices covering 38 000 patients in The Netherlands, we identified patients with atrial fibrillation using several search algorithms. Determinants of antithrombotic therapy were assessed using polytomous logistic regression analysis. Results. A total of 247 patients with atrial fibrillation were identified among 10 335 patients aged 55 years or over (prevalence 2.4%). Mean age was 77 years (range 55-95); 51% were male. Overall, 52% of the patients used coumarin and 27% used aspirin. About 50% of patients were also treated by a cardiologist. Referred patients were prescribed coumarin more often (63% versus 35%, P Ͻ 0.001). Prior stroke/transient ischaemic attack or systemic embolism [adjusted odds ratio (OR) 5.3, 95% confidence interval (CI) 1.1-24.8], and chronic heart failure (adjusted OR 2.1, 95% CI 0.8-5.1) were independent determinants for coumarin prescription. These associations were less strong for aspirin prescription. However, other established risk factors for future thromboembolic events, such as hypertension and diabetes mellitus, did not lead to higher prescription rates. In contrast, several factors not associated with thromboembolic events, such as chronic (versus paroxysmal) atrial fibrillation (adjusted OR 3.7, 95% CI 1.7-8.2) and longstanding (versus recent) diagnosis (adjusted OR 2.2, 95% CI 1.1-4.5), were also associated with higher coumarin prescription. Conclusion. These results illustrate that physicians' decisions about initiating antithrombotic therapy in atrial fibrillation are not evidence based. They are guided partly by thromboembolic risk stratification, but also by factors insignificant for thromboembolic risk.

Family Practice, 1997

To assess the methodological quality of double-blind placebo-controlled randomised clinical trial... more To assess the methodological quality of double-blind placebo-controlled randomised clinical trials (RCTs), regarding the effectiveness of antibiotic treatment in acute maxillary sinusitis in adults. Searching MEDLINE was searched from January 1966 to July 1996 using the keywords 'Respiratory Tract Infection' OR 'Sinusitis' AND 'Antibiotics'. In addition, the bibliographies of relevant articles were reviewed and the Cochrane Collaboration was consulted. The search strategy was limited to Dutch, English, French, German and Scandinavian studies.

Family Practice, 2005

Background. Benzodiazepines are frequently prescribed for sleep disturbances. However, benzodiaze... more Background. Benzodiazepines are frequently prescribed for sleep disturbances. However, benzodiazepines are associated with side effects, and may be ineffective when used for a prolonged period of time. Objectives. To investigate for individual patients whether placebo was as effective as temazepam, or whether 10 mg was as effective as 20 mg temazepam, and whether these results influenced their future temazepam use. Methods. A series of randomized double-blind N-of-1 trials were conducted in general practices in The Netherlands for patients who were using temazepam regularly. Each patient received five pairs of treatments consisting of one week of temazepam (10 or 20 mg) and one week of the control intervention (placebo or 10 mg temazepam). Per pair, the sequence of treatments was randomized. Main outcome measures were: time to fall asleep, and the individual main complaint. Results. Twelve out of 15 patients completed their trial. In three patients there was no difference, in five a large difference, and in four a small difference in favour of temazepam. At follow-up, seven patients had stopped or reduced their temazepam use. Conclusion. The results regarding the efficacy of temazepam varied across patients. N-of-1 trials seem to be valuable in patients who are motivated to stop or reduce their temazepam use. They clearly demonstrate the efficacy of temazepam, and may give patients additional confidence to discontinue regular hypnotic use. The value of N-of-1 trials for patients who are less motivated is unclear, as the size of treatment effect does not seem to influence future hypnotic use.

Family Practice, 2004

Background. Physical activity promotion in general practice is advocated though not incorporated ... more Background. Physical activity promotion in general practice is advocated though not incorporated into daily practice. Several barriers must be overcome to develop a feasible and acceptable programme. Objective. The aim of this study was to conduct a process evaluation of a physical activity promotion programme in general practice (PACE), in which patients visited their provider (GP or practice nurse) twice. Methods. Process evaluation was conducted by means of telephone-administered, semistructured interviews with providers and practice assistants. The main topics of the interviews were overall impression of PACE, PACE training, content and usability of the intervention materials, counselling, implementation of the intervention, and opportunities for future use. Results. In the 15 participating general practices, a total of 17 providers and 12 practice assistants were interviewed. The overall impression of the PACE programme was positive. Most providers experienced the provided material and training as helpful. Some problems concerning the number of forms used and patients having difficulties completing the forms were mentioned. Most providers (70.6%) spend 10 min or more discussing PACE during the first consultation. The second consultation mostly was completed within 10 min. Patients overestimating their level of physical activity was mentioned as the main barrier in providing the counselling. PACE was evaluated as suitable for implementation in Dutch general practice, and 60% of the providers actually intended using PACE in the future. Conclusion. The PACE programme was evaluated as being both acceptable and feasible in a selection of Dutch general practices. Positive adaptations will be made in order to implement PACE successfully in general practice at a wider scale.

Family Practice, 2002

Background. Postherpetic neuralgia (PHN) is a frequent complication of herpes zoster (HZ). Treatm... more Background. Postherpetic neuralgia (PHN) is a frequent complication of herpes zoster (HZ). Treatment results of this severe and long-lasting pain syndrome are often disappointing. From the point of view of possible prevention and early treatment, it is important to identify HZ patients who have an increased risk of developing PHN. Objectives. Our goals were to determine the incidence of HZ and PHN in a primary care population and to identify risk indicators for the occurrence of PHN. Methods. A search for HZ and PHN was conducted in a general practice research database, comprising 22 general practices and representing 49 000 people, over a 5-year period. Potential risk indicators were analysed using multivariate logistic regression. Results. A total of 837 patients had been diagnosed with HZ [incidence 3.4/1000 patients/year, 95% confidence interval (CI) 2.9-3.9]. The risk of developing PHN 1 month after the start of the zoster rash was 6.5% (95% CI 4.9-8.3). This risk was 11.7% (95% CI 8.5-14.9) for patients aged у55 years. Independent risk indicators for the occurrence of PHN were age [55-74 years, adjusted odds ratio (OR) 4.2, 95% CI 1.8-9.7; Ͼ75 years, OR 10.7, 95% CI 4.6-25.1] and ophthalmic localization (OR 2.3, 95% CI 1.0-4.6). Conclusions. The risk of developing PHN increases with age. Preventive strategies should focus on patients with herpes zoster aged Ͼ55 years and with ophthalmic localization.

Family Practice, 2007

Background. Earlier reports suggest limited clinical reasoning and substantial uncertainty of GPs... more Background. Earlier reports suggest limited clinical reasoning and substantial uncertainty of GPs in assessing patients suspected of dementia. Objective. To explore the predictors of GPs to decide on the presence and absence of dementia as well as the predictors of diagnostic confidence of GPs. Design. An observational study was set up among 107 patients of 64 GPs. The GPs were instructed to use the Dutch national dementia guideline on consecutive patients newly suspected of dementia and to register their assessment on a detailed form. The predictors of the presence and absence of dementia according to the GPs and their diagnostic confidence were explored by logistic regression analyses. Main outcome measures. Dependent variables: (i) presence and absence of dementia according to GPs and (ii) diagnostic confidence. Independent variables: clinical (cognitive, behavioural, somatic, functional), applications of recommendations, patient related and GP related. Results. Dementia was diagnosed in 67% of the suspected patients. The presence of dementia according to the GPs was positively associated with observed impairment of the higher cognitive functions, absence of depression and female gender of patients. The GPs expressed diagnostic confidence in 58% of the cases. This was positively associated with application of recommendations, ADL dependency, longer duration, informant availability, restless behaviour and a patient's female gender. Use of the Mini Mental Status Examination was not associated with confidence. Conclusions. GPs seem to base the diagnosis of dementia on rational grounds. Application of the dementia guideline's recommendations may contribute to more diagnostic confidence.

European Spine Journal, 2007

An intervention that can prevent low back pain (LBP) becoming chronic, may not only prevent great... more An intervention that can prevent low back pain (LBP) becoming chronic, may not only prevent great discomfort for patients, but also save substantial costs for the society. Psychosocial factors appear to be of importance in the transition of acute to chronic LBP. The aim of this study was to compare the cost-effectiveness of an intervention aimed at psychosocial factors to usual care in patients with (sub)acute LBP. The study design was an economic evaluation alongside a cluster-randomized controlled trial, conducted from a societal perspective with a follow-up of 1 year. Sixty general practitioners in 41 general practices recruited 314 patients with non-specific LBP of less than 12 weeks' duration. General practitioners in the minimal intervention strategy (MIS) group explored and discussed psychosocial prognostic factors. Usual care (UC) was not protocolized. Clinical outcomes were functional disability (Roland-Morris Disability Questionnaire), perceived recovery and health-related quality of life (Eu-roQol). Cost data consisted of direct and indirect costs and were measured by patient cost diaries and general practitioner registration forms. Complete cost data were available for 80% of the patients. Differences in clinical outcomes between both the groups were small and not statistically significant. Differences in cost data were in favor of MIS. However, the complete case analysis and the sensitivity analyses with imputed cost data were inconsistent with regard to the statistical significance of this difference in cost data. This study presents conflicting points of view regarding the cost-effectiveness of MIS. We conclude that (Dutch) general practitioners, as yet, should not replace their usual care by this new intervention.

The European Journal of Public Health, 2009

Background: The primary care evaluation of mental disorders (PRIME-MD) can be seen as characteris... more Background: The primary care evaluation of mental disorders (PRIME-MD) can be seen as characteristic for successive refinements of criteria and structured interview techniques for diagnosing psychiatric disorders in primary care. It is one of the most widely used instruments, but there is no evidence to support its test-retest reliability. Methods: With 1-week intervals between interviews, a test-retest study of the PRIME-MD was conducted in a general practice population of 100 distressed patients (20-to 60-years old) who were on sick leave. Results: Almost everyone (89%) received one or more diagnoses at both measurements, and there was fair total agreement (= 0.27). The best agreement was found for more severe threshold disorders [major depressive disorder (= 0.58), dysthymia (= 0.57), and generalized anxiety disorder (= 0.59)], while we found indefinite results for the sub-threshold disorders [anxiety disorder not otherwise specified (NOS) (=.30), minor depressive disorder (= À0.03), and somatoform disorder NOS (= 0.11)]. Conclusion: The PRIME-MD is one of the few instruments in primary care that actually diagnoses specific mental disorders according to the DSM criteria. However, there was a failure to adequately classify sub-threshold disorders. Mental disorders, as seen in primary care, encompass important specific symptoms and clinical syndromes that vary in duration and severity over time, but they also encompass an admixture of somatic and psychological symptoms that do not match current diagnostic systems. This most likely resulted in methodological uncertainty about the level of agreement. Diagnostic criteria in psychiatry need to be operationalized for use in primary care and require further evaluation.

Epidemiology and Infection, 2002

Influenza immunization rates among young asthmatics remain unsatisfactory due to persistent conce... more Influenza immunization rates among young asthmatics remain unsatisfactory due to persistent concern about the impact of influenza and the benefits of the vaccine. We assessed the effectiveness of the conventional inactivated trivalent sub-unit influenza vaccine in reducing acute respiratory disease in asthmatic children. We conducted a two-season retrospective cohort study covering the 1995–6 and 1996–7 influenza outbreaks in 22 computerized primary care practices in the Netherlands. In total, 349 patients aged between 0 and 12 years meeting clinical asthma-criteria were included; 14 children were lost to follow-up in the second season. The occurrence of physician-diagnosed acute respiratory disease episodes including influenza-like illness, pneumonia, bronchitis, bronchiolitis, asthma exacerbation and acute otitis media in vaccinated and unvaccinated children were compared after adjustments for age, prior health care and medication use. The occurrence of acute respiratory disease i...

Diabetes Care, 2005

Potential role of glial cell linederived neurotrophic factor receptors in Mü ller glial cells dur... more Potential role of glial cell linederived neurotrophic factor receptors in Mü ller glial cells during light-induced retinal degeneration.

Clinical Practice and Epidemiology in Mental Health, 2007

Background: The Sense of Competence Questionnaire (SCQ) was originally developed for informal car... more Background: The Sense of Competence Questionnaire (SCQ) was originally developed for informal caregivers of patients with diagnosed dementia. In order to study the validity and usefulness of the SCQ when applied to informal caregivers of older adults with dementia symptoms (i.e. cognitive impairment, pre-diagnostic dementia or dementia in its early stages), we investigated the construct validity, feasibility, subscales, homogeneity, and floor and ceiling effects in this new target population. Methods: A psychometric evaluation was performed among 99 informal caregivers. To investigate construct validity, hypotheses were tested, concerning the association between sense of competence and burden, mental quality of life, depressive symptoms, and mastery. To investigate feasibility, response rate and the proportion of missing data were explored for each item. An exploratory principal component analysis was used to investigate whether the SCQ comprises the three subscales established in previous studies. Homogeneity was assessed for each subscale with Cronbach's α and item-total correlations. Floor and ceiling effects were explored. Results: Most hypotheses on construct validity were rejected. Only the subscale 'consequences of involvement in care' was found to be partly valid. Feasibility: 93 out of 99 persons completed the SCQ. The proportion of unanswered items per item ranged from 0-3%. Subscales: the SCQ comprises the three expected subscales. Homogeneity: Cronbach's alpha and item-total correlations of the three subscales were satisfactory. A ceiling effect occurred on the subscale 'satisfaction with the care recipient'. Conclusion: The three subscales of the SCQ showed good homogeneity and feasibility, but their validity is insufficient: only the subscale 'consequences of involvement' was found to be partly valid. The two other subscales might not be relevant yet for the new target population, since many of the items on these scales