Jakob Bjorner | University of Copenhagen (original) (raw)

Papers by Jakob Bjorner

Journal of the American Heart Association

Journal of Patient-Reported Outcomes

Background: Psychometric analyses of patient reported outcomes typically use either classical tes... more Background: Psychometric analyses of patient reported outcomes typically use either classical test theory (CTT), item response theory (IRT), or Rasch measurement theory (RTM). The three papers from the ISOQOL Psychometrics SIG examined the same data set using the tree different approaches. By comparing the results from these papers, the current paper aims to examine the extent to which conclusions about the validity and reliability of a PRO tool depends on the selected psychometric approach. Main text: Regarding the basic statistical model, IRT and RTM are relatively similar but differ notably from CTT. However, modern applications of CTT diminish these differences. In analyses of item discrimination, CTT and IRT gave very similar results, while RTM requires equal discrimination and therefore suggested exclusion of items deviating too much from this requirement. Thus, fewer items fitted the Rasch model. In analyses of item thresholds (difficulty), IRT and RMT provided fairly similar results. Item thresholds are typically not evaluated in CTT. Analyses of local dependence showed only moderate agreement between methods, partly due to different thresholds for important local dependence. Analyses of differential item function (DIF) showed good agreement between IRT and RMT. Agreement might be further improved by adjusting the thresholds for important DIF. Analyses of measurement precision across the score range showed high agreement between IRT and RMT methods. CTT assumes constant measurement precision throughout the score range and thus gave different results. Category orderings were examined in RMT analyses by checking for reversed thresholds. However, this approach is controversial within the RMT society. The same issue can be examined by the nominal categories IRT model. Conclusions: While there are well-known differences between CTT, IRT and RMT, the comparison between three actual analyses revealed a great deal of agreement between the results from the methods. If the undogmatic attitude of the three current papers is maintained, the field will be well served.

CNS Spectrums

IntroductionTardive dyskinesia (TD), an often-irreversible movement disorder typically caused by ... more IntroductionTardive dyskinesia (TD), an often-irreversible movement disorder typically caused by exposure to antipsychotics, most commonly affects the face, mouth, and tongue and may be debilitatingObjectiveTo investigate TD burden on patients’ quality of life and functionalityMethodsAdults with clinician-confirmed schizophrenia, bipolar disorder, or major depressive disorder participated in an observational study. Approximately half (47%) ofparticipants had a clinician-confirmed TD diagnosis. Participants completed the SF-12v2 Health Survey® (SF-12v2), Quality of Life Enjoyment and Satisfaction Questionnaire Short Form (Q-LES-Q-SF), social withdrawal subscale of the Internalized Stigma of Mental Illness scale (SW-ISMI), and rated the severity of their TD symptoms. Group differences in SF-12v2 physical and mental component summaries (PCS and MCS), Q-LES-Q-SF, and SW-ISMI scores were analyzed.ResultsTD (n=79) and non-TD (n=90) groups were similar in age, gender, and number of patient...

Quality of life research : an international journal of quality of life aspects of treatment, care and rehabilitation, 2018

Patient-reported outcome (PRO) measures originally developed for paper administration are increas... more Patient-reported outcome (PRO) measures originally developed for paper administration are increasingly being administered electronically in clinical trials and other health research studies. Three published meta-analyses of measurement equivalence among paper and electronic modes aggregated findings across hundreds of PROs, but there has not been a similar meta-analysis that addresses a single PRO, partly because there are not enough published measurement equivalence studies using the same PRO. Because the SF-36 Health Survey (SF-36) is a widely used PRO, the aim of this study was to conduct a meta-analysis of measurement equivalence studies of this survey. A literature search of several medical databases used search terms for variations of "SF-36" or "SF-12" and "equivalence" in the title or abstract of English language publications. The eight scale scores and two summary measures of the SF-36 and SF-12 were transformed to norm-based scores (NBS) using...

BMJ open, Jan 30, 2018

Sickness absence has been used as a central indicator of work disability, but has mainly been exa... more Sickness absence has been used as a central indicator of work disability, but has mainly been examined in single diseases, with limited follow-up time. This study identified the risk of long-term sickness absence (LTSA) of 32 chronic disease groups in the first year after diagnosis and the subsequent years. We identified chronic disease groups prevalent in the work force (26 physical and 6 mental conditions) requiring all levels of care (primary, secondary, tertiary), by national registers of diagnoses from all hospital visits and prescribed medicine in Denmark from 1994 to 2011. A general population sample within the working age range (18-59 years) was drawn by Statistics Denmark. Participants not working before and during the follow-up period were excluded. A total of 102 746 participants were included. HRs of transitions from work to LTSA of each of the chronic conditions were estimated in Cox proportional hazards models for repeated events-distinguishing between risk within the ...

Hormones (Athens, Greece), 2018

The thyroid-related patient-reported outcome measure ThyPRO is currently the most reliable and va... more The thyroid-related patient-reported outcome measure ThyPRO is currently the most reliable and valid instrument for the measurement of thyroid-related quality of life. The objective of the current study was to translate the original (85 items) and short (39 items) versions of ThyPRO into the Greek language as well as to validate and culturally adapt ThyPRO among the Greek population. Translation of patient-reported outcomes was done according to standard methodology. Following the translation process, the Greek version of ThyPRO (ThyPROgr) was validated in consecutive patients with thyroid diseases who visited the outpatient clinics of the Department of Endocrinology, "Hippokration" General Hospital, Thessaloniki, Greece, between September and December 2016. To test cross-cultural validity, analysis of differential item functioning (DIF) between the original Danish and the new Greek version, using ordinal logistic regression, was applied. Cross-cultural validity of the Gre...

Quality of life research : an international journal of quality of life aspects of treatment, care and rehabilitation, Jan 14, 2017

The purpose of this study was to adapt different domains of an existing retrospective questionnai... more The purpose of this study was to adapt different domains of an existing retrospective questionnaire to momentary versions, to use and assess cognitive interviewing for evaluating the new versions, and to compare momentary compatibility (i.e. an item's potential to be validly converted to a momentary version) across different scales. Initial momentary versions of retrospective patient-reported outcomes were produced by converting present perfect tense wording to present tense wording. Cognitive interviews were conducted iteratively with 21 patients to determine which reference period they actually employed, and to identify problems with new, revised versions. A think-aloud interview protocol was supplemented with non-specific concurrent and specific retrospective probing. The momentary compatibility of each item was evaluated by calculating the proportion of interviews wherein momentary reference periods were identified; problems were categorized according to cognitive aspects of...

Scandinavian Journal of Public Health

Aims: Most previous prospective studies have examined workplace social capital as a resource of t... more Aims: Most previous prospective studies have examined workplace social capital as a resource of the individual. However, literature suggests that social capital is a collective good. In the present study we examined whether a high level of workplace aggregated social capital (WASC) predicts a decreased risk of individual-level long-term sickness absence (LTSA) in Danish private sector employees. Methods: A sample of 2043 employees (aged 18–64 years, 38.5% women) from 260 Danish private-sector companies filled in a questionnaire on workplace social capital and covariates. WASC was calculated by assigning the company-averaged social capital score to all employees of each company. We derived LTSA, defined as sickness absence of more than three weeks, from a national register. We examined if WASC predicted employee LTSA using multilevel survival analyses, while excluding participants with LTSA in the three months preceding baseline. Results: We found no statistically significant associa...

European Heart Journal

Aims Studies suggest that people who work long hours are at increased risk of stroke, but the ass... more Aims Studies suggest that people who work long hours are at increased risk of stroke, but the association of long working hours with atrial fibrillation, the most common cardiac arrhythmia and a risk factor for stroke, is unknown. We examined the risk of atrial fibrillation in individuals working long hours (> _55 per week) and those working standard 35-40 h/week.

BioMed Research International

Introduction. The objective of this study is, among half-year intensive care survivors, to determ... more Introduction. The objective of this study is, among half-year intensive care survivors, to determine whether self-assessment of health can predict two-year mortality. Methods. The study is a prospective cohort study based on the Procalcitonin and Survival Study trial. Half-year survivors from this 1200-patient multicenter intensive care trial were sent the SF-36 questionnaire. We used both a simple one-item question and multiple questions summarized as a Physical Component Summary (PCS) and a Mental Component Summary (MCS) score. The responders were followed for vital status 730 days after inclusion. Answers were dichotomized into a low-risk and a high-risk group and hazard ratios (HR) with 95% confidence interval (CI) were calculated by Cox proportional hazard analyses. Conclusion. We found that self-rated health measured by a single question was a strong independent predictor of two-year all-cause mortality (HR: 1.8; 95% CI: 1.1–3.0). The multi-item component scores of the SF-36 a...

Pilot and feasibility studies, 2017

The Patient-Reported Outcome Measurement Information System (PROMIS) is an assessment system that... more The Patient-Reported Outcome Measurement Information System (PROMIS) is an assessment system that aims to provide more valid, reliable, responsive, and precise patient-reported outcome (PRO) measures than has been previously available. This paper documents the translation of the Physical Function item bank into Danish. We followed the PROMIS standard procedure, including: 1) two independent translations, 2) back translation, 3) independent reviews of translation quality, and 4) cognitive interviews with a representative sample of the adult population from the municipality of Copenhagen. After each phase, the new information was reviewed and the Danish version of the PROMIS Physical Function items was revised, if warranted. Relatively few problems were related to translation in itself and such problems could be fixed by changes in item wordings to fit the Danish context. Cognitive testing revealed problem of a general issue: annoyance in case of mismatch between respondents' func...

Arthritis research & therapy, Jan 21, 2017

Physical function (PF) is a core patient-reported outcome domain in clinical trials in rheumatic ... more Physical function (PF) is a core patient-reported outcome domain in clinical trials in rheumatic diseases. Frequently used PF measures have ceiling effects, leading to large sample size requirements and low sensitivity to change. In most of these instruments, the response category that indicates the highest PF level is the statement that one is able to perform a given physical activity without any limitations or difficulty. This study investigates whether using an item format with an extended response scale, allowing respondents to state that the performance of an activity is easy or very easy, increases the range of precise measurement of self-reported PF. Three five-item PF short forms were constructed from the Patient-Reported Outcomes Measurement Information System (PROMIS®) wave 1 data. All forms included the same physical activities but varied in item stem and response scale: format A ("Are you able to …"; "without any difficulty"/"unable to do");...

Rheumatology, 2017

Objectives. The aim was to study work ability in patients with RA compared with the general popul... more Objectives. The aim was to study work ability in patients with RA compared with the general population by investigating the rates and risks of long-term sickness absence, unemployment and disability pension, and the chance of returning to work and the changes in these risks over time (19942011). Methods. This was a cohort study with up to 17 years of follow-up (mean 6.95 years/person) including 6677 RA patients of working age (identified in the nationwide DANBIO registry) and 56 955 matched controls from the general population. A multi-state model was used to analyse all shifts between the work-related states (long-term sickness absence, unemployment and disability pension, as well as the chance of returning to work) and calculate hazard rates (HRs). Analyses were stratified by disease duration and controlled for socio-demographic factors, physical job exposure and somatic and psychiatric comorbidities. Results. RA patients had increased risk of long-term sickness absence (e.g. early RA:

CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne, Jan 3, 2016

Job insecurity has been associated with certain health outcomes. We examined the role of job inse... more Job insecurity has been associated with certain health outcomes. We examined the role of job insecurity as a risk factor for incident diabetes. We used individual participant data from 8 cohort studies identified in 2 open-access data archives and 11 cohort studies participating in the Individual-Participant-Data Meta-analysis in Working Populations Consortium. We calculated study-specific estimates of the association between job insecurity reported at baseline and incident diabetes over the follow-up period. We pooled the estimates in a meta-analysis to produce a summary risk estimate. The 19 studies involved 140 825 participants from Australia, Europe and the United States, with a mean follow-up of 9.4 years and 3954 incident cases of diabetes. In the preliminary analysis adjusted for age and sex, high job insecurity was associated with an increased risk of incident diabetes compared with low job insecurity (adjusted odds ratio [OR] 1.19, 95% confidence interval [CI] 1.09-1.30). I...

Radiation Oncology, 2016

Background: Radiotherapy (RT) in combination with androgen deprivation therapy (ADT) for prostate... more Background: Radiotherapy (RT) in combination with androgen deprivation therapy (ADT) for prostate cancer (PCa) carries a risk of gastrointestinal (GI) and genitourinary toxicity, which might affect the quality of life (QoL). The purpose of this study was to assess the QoL in patients with PCa before, during and after radiotherapy (RT) and to compare the QoL 1 year after RT to a normal population. Methods: The QoL was evaluated prospectively by the self-administered questionnaire SF-36 in 87 patients with PCa. The SF-36 was completed before RT (baseline), at start of RT, at end of RT and 1 year after RT. A mixed model analysis was used to determine the changes in QoL at each time point compared to baseline. The patients' QoL 1 year after RT was compared to a normal population consisting of 462 reference subjects matched on age and education. Results: One year after RT, patients reported significantly less pain and significantly fewer limitations due to their physical health compared to baseline. Compared to the normal population, patients reported significantly less pain 1 year after RT. However, patients also reported significantly less vitality, worse mental health as well as significantly more limitations due to physical and mental health 1 year after RT compared to the normal population. Conclusions: In this study, patients with PCa did not experience significant impairment in the QoL 1 year after RT compared to baseline. However, patients reported significantly worse mental health before, during and 1 year after RT compared to the normal population.

Qual Life Res, 2003

Background: Measurement of headache impact is important in clinical trials, case detection, and t... more Background: Measurement of headache impact is important in clinical trials, case detection, and the clinical monitoring of patients. Computerized adaptive testing (CAT) of headache impact has potential advantages over traditional fixed-length tests in terms of precision, relevance, real-time quality control and flexibility. Objective: To develop an item pool that can be used for a computerized adaptive test of headache impact. Methods: We analyzed responses to four well-known tests of headache impact from a population-based sample of recent headache sufferers (n ¼ 1016). We used confirmatory factor analysis for categorical data and analyses based on item response theory (IRT). Results: In factor analyses, we found very high correlations between the factors hypothesized by the original test constructers, both within and between the original questionnaires. These results suggest that a single score of headache impact is sufficient. We established a pool of 47 items which fitted the generalized partial credit IRT model. By simulating a computerized adaptive health test we showed that an adaptive test of only five items had a very high concordance with the score based on all items and that different worst-case item selection scenarios did not lead to bias. Conclusion: We have established a headache impact item pool that can be used in CAT of headache impact.

The Journal of Rheumatology, Jun 1, 2007

Patient reported outcomes (PRO) are considered central outcome measures for both clinical trials ... more Patient reported outcomes (PRO) are considered central outcome measures for both clinical trials and observational studies in rheumatology. More sophisticated statistical models, including item response theory (IRT) and computerized adaptive testing (CAT), will enable critical evaluation and reconstruction of currently utilized PRO instruments to improve measurement precision while reducing item burden on the individual patient. Methods. We developed a domain hierarchy encompassing the latent trait of physical function/disability from the more general to most specific. Items collected from 165 English-language instruments were evaluated by a structured process including trained raters, modified Delphi expert consensus, and then patient evaluation. Each item in the refined data bank will undergo extensive analysis using IRT to evaluate response functions and measurement precision. CAT will allow for real-time questionnaires of potentially smaller numbers of questions tailored directly to each individual's level of physical function. Results. Physical function/disability domain comprises 4 subdomains: upper extremity, trunk, lower extremity, and complex activities. Expert and patient review led to consensus favoring use of presenttense "capability" questions using a 4-or 5-item Likert response construct over past-tense "performance" items. Floor and ceiling effects, attribution of disability, and standardization of response categories were also addressed. Conclusion. By applying statistical techniques of IRT through use of CAT, existing PRO instruments may be improved to reduce questionnaire burden on the individual patients while increasing measurement precision that may ultimately lead to reduced sample size requirements for costly clinical trials.

Journal of Clinical Epidemiology, Dec 31, 2004

Background and Objective: This study examined the psychometric properties and equivalence of the ... more Background and Objective: This study examined the psychometric properties and equivalence of the six-item Headache Impact Test (HIT-6) across 11 languages in 14 countries. Methods: A multicenter, international cross-sectional study conducted in a primary care setting. Data obtained from 1,171 adults from 14 countries who consulted their primary care physician for headache completed the HIT-6 questionnaire and a headache survey were included in this analysis. Item-level statistics (e.g., range of response choices used by participants), item-scale statistics (e.g., item-total correlations), scale level statistics (e.g., internal consistency reliability), and tests of differential item functioning were conducted to examine the psychometric properties of all HIT-6 translations and their comparability across translations. Results: Across languages, missing data were low, item-scale correlations were high, reliability was adequate, and item-level statistics were generally comparable. We found only minor differential item functioning, suggesting that the HIT-6 translations are equivalent to the U.S. English form. Conclusions: Psychometric analyses indicate that most HIT-6 translations

Thyroid, 2016

The treatment of hyperthyroidism is aimed at improving health-related quality of life (HRQoL) and... more The treatment of hyperthyroidism is aimed at improving health-related quality of life (HRQoL) and reducing morbidity and mortality. However, few studies have used validated questionnaires to assess HRQoL prospectively in such patients. The purpose of this study was to assess the impact of hyperthyroidism and its treatment on HRQoL using validated disease-specific and generic questionnaires. This prospective cohort study enrolled 88 patients with Graves&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; hyperthyroidism and 68 with toxic nodular goiter from endocrine outpatient clinics at two Danish university hospitals. The patients were treated with antithyroid drugs, radioactive iodine, or surgery. Disease-specific and generic HRQoL were assessed using the thyroid-related patient-reported outcome (ThyPRO) and the Medical Outcomes Study 36-item Short Form (SF-36), respectively, evaluated at baseline and six-month follow-up. The scores were compared with those from two general population samples who completed ThyPRO (n = 739) and SF-36 (n = 6638). Baseline scores for patients with Graves&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; hyperthyroidism and toxic nodular goiter were significantly worse than those for the general population scores on all comparable ThyPRO scales and all SF-36 scales and component summaries. ThyPRO scores improved significantly with treatment on all scales in Graves&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; hyperthyroidism and four scales in toxic nodular goiter, while SF-36 scores improved on five scales and both component summaries in Graves&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; hyperthyroidism and only one scale in toxic nodular goiter. In Graves&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; hyperthyroidism, large treatment effects were observed on three ThyPRO scales (Hyperthyroid Symptoms, Tiredness, Overall HRQoL) and moderate effects on three scales (Anxiety, Emotional Susceptibility, Impaired Daily Life), while moderate effects were seen in two ThyPRO scales in toxic nodular goiter (Anxiety, Overall HRQoL). However, significant disease-specific and generic HRQoL deficits persisted on multiple domains across both patient groups. Graves&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; hyperthyroidism and toxic nodular goiter cause severe disease-specific and generic HRQoL impairments, and HRQoL deficits persist in both patient groups six months after treatment. These data have the potential to improve communication between physicians and patients by offering realistic estimates of expected HRQoL impairments and treatment effects. Future studies should identify risk factors for persistent HRQoL deficits, compare HRQoL effects of the various therapies, and thereby aid in determining the optimal treatment strategies.

PLOS ONE, 2016

Background Hypothyroidism is often diagnosed, and subsequently treated, due to health-related qua... more Background Hypothyroidism is often diagnosed, and subsequently treated, due to health-related quality of life (HRQL) issues. However, HRQL following treatment has never previously been assessed in longitudinal descriptive studies using validated instruments. Objective To investigate disease-specific (ThyPRO) and generic (SF-36) HRQL, following levothyroxine therapy in patients with hypothyroidism due to autoimmune thyroiditis. Methods This prospective cohort study was set at endocrine outpatient clinics at two Danish university hospitals. Seventy-eight consecutive patients were enrolled and completed HRQL questionnaires before, six weeks, and six months after initiation of levothyroxine therapy. Normative ThyPRO (n = 739) and SF-36 (n = 6,638) data were available for comparison and changes in HRQL following treatment were estimated and quantified. Results Prior to treatment, all ThyPRO scales were significantly impacted (p<0.0001), compared to the general population sample. The same was observed for seven of eight SF-36 scales, the exception being Bodily Pain. Tiredness (ThyPRO) and Vitality (SF-36) were the most PLOS ONE |