Musculoskeletal pain in the obese: a comparison with a... : PAIN (original) (raw)
1 Introduction
Musculoskeletal pain is a major medical problem (Andersson et al., 1993; Bovim et al., 1994; Carey et al., 1996; Leboeuf-Yde et al., 1996; Linton et al., 1998; Mäkelä et al., 1991) associated with disability and economic loss (Cassidy et al., 1998; Leijon et al., 1998; Mäntyselkä et al., 2001). The risk factors for musculoskeletal pain include age, occupational exposure, psychosocial factors and physical activity (Fredriksson et al., 1999; Hellsing and Bryngelsson, 2000; Miranda et al., 2001; van der Windt et al., 2000). Musculoskeletal problems are more common in women than in men (Bovim et al., 1994; Leijon et al., 1998; Nordander et al., 1999; Rollman and Lautenbacher, 2001).
Obesity and overweight are associated with musculoskeletal pain, as well as with osteoarthritis of the knee and hip (WHO, 2000; Felson et al., 2000; Hellsing and Bryngelsson, 2000; Miranda et al., 2001; Quesenberry et al., 1998). Further, obesity surgery and weight loss has been shown to reduce the risk of musculoskeletal problems and knee osteoarthritis (Felson et al., 1992, 1997; McGoey et al., 1990; The Danish Obesity Project, 1979).
In the present study, we compare the prevalence of self-reported, work-restricting musculoskeletal pain in obese subjects with that in a general population. Further, long-term changes in the percentage of afflicted individuals are analyzed among patients undergoing surgical or conventional obesity treatment.
2 Methods
2.1 Swedish obese subjects study
The Swedish obese subjects (SOS) study is an ongoing nationwide research project which started in 1987 (Sjöström et al., 1992), with the primary aim of determining whether mortality and morbidity rates among the obese can be reduced by intentional weight reduction. The SOS study consists of three parts: a cross-sectional registry study of 6328 obese subjects; a longitudinal controlled intervention study of 4047 obese subjects and a cross-sectional reference study of 1135 randomly selected subjects from the general population.
The ‘registry study’ is basically an extensive health examination and the aim is to characterize obese subjects with respect to genetics, medical history, metabolic aberrations, body fat distribution, food habits, psychologic and socio-economic variables. The registry study also serves as a recruitment base for the subsequent intervention study.
In the ‘intervention study’, 2010 surgically treated obese patients are compared with a control group of 2037 matched obese patients receiving conventional treatment in primary health care. Follow-up is performed at regular out-patient visits and self-administered questionnaires are dispatched at 6 months, 1, 2, 3, 4, 6, 8, 10, 15 and 20 years after inclusion. The inclusion of patients in the intervention study was completed in January 2001. The inclusion criteria were age (37–60 years) and a body mass index (BMI) of ≥34 kg/m2 for men and ≥38 kg/m2 for women.
Patients in the SOS registry study who were interested in surgery and met the inclusion criteria but not the exclusion criteria for the intervention study were invited to discuss bariatric surgery with a surgeon. Subjects who subsequently accepted surgery form the surgical group. The permitted operations were gastric banding, vertical banded gastroplasty (VBG) or gastric bypass, according to local practice at the 25 collaborating surgical departments (Sjöström, 2000). Patients in the conventionally treated group received the same treatment as obese patients generally do at the 480 collaborating primary health care centers, including dietary advice, behavior modification, very low-caloric diet, physical training or pharmaceutical treatment, according to local practice. The conventionally treated control group was selected from eligible patients in the registry study by a computerized matching procedure, taking account of sex and 18 matching variables (Sjöström et al., 1992).
The SOS reference study is a population study conducted between 1994 and 1999 (Lissner et al., 1998). A random sample of 2037 men and women aged 37–60 years was selected from the population registry and 1135 agreed to participate. They were examined with identical questionnaires and a similar health examination as participants in the SOS registry study. Follow-up examinations are planned after 10, 15 and 20 years.
The ethics committees at all Swedish medical faculties have approved the SOS and SOS reference studies and informed consent was obtained from all subjects.
2.2 Study populations
In the cross-sectional part of the present study, we used information about all 6328 patients in the SOS registry study and the 1135 SOS reference subjects. In the longitudinal part of the present study, the 1879 conventionally treated patients and the 1854 operated patients, who were included before 31 October 1999, form the study group for analyses of 2-year changes. Of these, 348 controls (18.5%) and 156 operated patients (8.4%) were lost to follow-up. Only subjects who completed the 2-year examination were used in the analyses.
For the 6-year follow-up, the 1235 controls and 1312 operated patients included before 31 October 1995 were used. After 6 years, 29.3 and 20.5% in the control and operated group, respectively, were lost to follow-up, leaving 873 and 1043 subjects with complete 6-year data.
2.3 Measurements and questionnaires
Body weight was measured to the nearest 0.1 kg and height to the nearest 0.01 m. BMI was calculated as weight divided by height squared (kg/m2).
Information about work-restricting pain in the neck and back area and in the hip, knee and ankle joints was collected through self-administered questionnaires. These five different locations were analyzed separately and combined (i.e. work-restricting pain in at least one of the five locations). In the cross-sectional study, the SOS registry and SOS reference subjects completed the questionnaires once. Patients in the longitudinal intervention study answered the questions at inclusion and again after 0.5, 1, 2, 3, 4 and 6 years.
The questions used were formulated as:
Have you had pain in the (body area of interest) that periodically restricted your working capacity during the past 12 months? Yes/No
In the longitudinal analyses, subjects reporting pain at least once during the given follow-up period were defined as cases. This was done separately for each body location.
Information on smoking habits, leisure time physical activity and current working status was obtained from self-administered questionnaires. The physical activity level was coded as sedentary, moderate or regular. Subjects reporting no working hours during a week due to early retirement or sick leave were classified as ‘not working’.
2.4 Statistics
In the cross-sectional part of the study, the gender-specific prevalence of pain in the neck and back areas and in the hip, knee and ankle joints was analyzed using a logistic regression model, adjusting for age, smoking, working status and physical activity. We report odds ratios (OR) with 95% confidence intervals (CI). To study the relationship between BMI and the prevalence of pain in the five locations, the SOS and SOS reference groups were divided into gender-specific BMI tertiles.
In the longitudinal analyses, gender-specific incidence rates were compared between the two treatment groups using logistic regression models, adjusting for baseline differences in age, smoking, working status and physical activity levels. Similarly, recovery rates among those who reported pain at baseline were compared using a logistic regression model. ORs and 95% CIs are reported. All the analyses were performed using the Stata statistics package (StataCorp, 2001).
3 Results
3.1 Cross-sectional comparison
Table 1 shows the gender-specific characteristics of the SOS registry and SOS reference populations used in the cross-sectional analysis. The reference population was slightly older than the obese population. Subjects in the SOS registry study were markedly heavier than subjects in the SOS reference study. The percentage of people not working regularly was higher among the obese subjects and they also had a more sedentary lifestyle. Subjects who were selected to the reference study but did not agree to participate did not differ from the participants with respect to age and sex distribution.
Baseline characteristics of subjects in the SOS registry and SOS reference studies
The prevalence of work-restricting musculoskeletal pain (all locations, both sexes) was higher in the obese (Fig. 1). The ORs for having musculoskeletal pain (obese vs. reference group) ranged from 1.7 for back pain in men to 9.9 for pain in the ankle joints in women. In the SOS reference group, women more frequently reported pain in the neck and hips compared with men (P<0.01 both comparisons, adjusted for age, BMI, smoking, working status and physical activity). In the obese SOS population, work-restricting pain was more prevalent in women than in men, irrespective of body area (adjusted P<0.01 for all comparisons).
Prevalence of work-restricting musculoskeletal pain in five body locations in the SOS registry (obese subjects) and reference (general population) studies. Prevalences and 95% CI are unadjusted, OR with 95% CIs are adjusted for age, smoking, working status and physical activity level. ***P<0.001. Total indicates the percentage of subjects reporting pain in at least one of five body locations.
The percentage of subjects reporting pain in at least one of five locations (combined measure) was 57.9% in the obese men, compared with 32.2% among reference men (Fig. 1). The corresponding percentages in women were 68.0 and 37.0%, respectively.
In order to relate the prevalence of work-restricting musculoskeletal pain to body weight, subjects in the SOS reference and SOS registry studies were divided into tertiles of BMI (Fig. 2). Among the reference women, the prevalence of pain increased with increasing BMI and this was statistically significant for all locations except the back. The association between BMI and musculoskeletal pain was similar in the reference men. For obese patients in the SOS registry study, no clear relationship between BMI and musculoskeletal pain was observed.
Prevalence of work-restricting musculoskeletal pain in five body locations in relation to BMI in the SOS registry (obese subjects) and SOS reference (general population) studies. Prevalences are adjusted for age, smoking, working status and physical activity level. Total indicates the percentage of subjects reporting pain in at least one of five body locations. *P<0.05 adjusted for age, smoking, working status and physical activity.
3.2 Longitudinal comparison
The baseline characteristics of the obese subjects included in the longitudinal part of the present study are shown in Table 2. Operated subjects completing the 2-year follow-up were heavier than conventionally treated controls. The percentage of subjects not working was similar in both groups, while operated patients had a more sedentary lifestyle. In general, the operated group reported more pain at the baseline than the control group. The baseline characteristics of the subjects completing the 2-year follow-up were similar to those of the 6-year completers (data not shown). The operated group had markedly larger weight reductions after 2 and 6 years (Table 3).
Baseline characteristics of operated and conventionally treated patients who completed the 2-year follow-up in the SOS intervention study
Weight change over 2 and 6 years in operated and conventionally treated patients in the SOS intervention study
Subjects who dropped out from the SOS study during follow-up were slightly older, and more often smokers compared to those who completed the follow-up. The prevalence of neck and back pain at baseline was lower among the drop-outs, whereas the prevalence of pain in the other body locations were similar in these two groups.
Among women reporting no work-restricting pain in the knee and ankle joints at baseline, the risk of having pain at the 2- and 6-year follow-ups was significantly lower in the operated group compared with the control group (adjusted ORs operated group vs. controls ranging from 0.51 to 0.71) (Fig. 3). Similarly, in men, the risk of work-restricting pain in the knee and ankle joints was lower in the operated group, although only pain in the ankle joints at the 6-year follow-up reached statistical significance.
Incidence of work-restricting musculoskeletal pain in five body locations in the SOS intervention study. Subjects did not report work-restricting pain in the respective body locations at baseline. Incidence proportions are unadjusted, OR and _P_-values are adjusted for age, smoking, working status and physical activity. ***P<0.001, *P<0.05, (*)P<0.10. The upper panel shows the 2-year follow-up and the lower panel the 6-year follow-up.
The percentages of subjects reporting pain at baseline, but not at follow-up, are shown in Fig. 4. In women, the 2-year recovery rates were higher in the operated group compared with the control group for all five body locations. The pattern was similar at the 6-year follow-up and statistically significant for the knee and ankle joints. In men, the operated subjects reported fewer problems with work-restricting pain in the knee and ankle joints at the 2-year follow-up; however, this difference was reduced after 6 years.
Recovery from work-restricting musculoskeletal pain in five body locations in the SOS intervention study. Subjects reported work-restricting pain in the respective body locations at baseline. Recovery proportions are unadjusted, OR and _P_-values are adjusted for age, smoking, working status and physical activity. ***P<0.001, **P<0.01, *P<0.05, (*)P<0.10. The upper panel shows the 2-year follow-up and the lower panel the 6-year follow-up.
After pooling data from the control and operated groups, the 2- and 6-year incidence and recovery rates were related to the degree of weight change. In general, subjects losing weight had lower incidence and higher recovery rates than subjects who increased in weight (Fig. 5). The results were similar when this analysis was performed in the operated group alone.
Two- and 6-year incidence and recovery rates for work-restricting musculoskeletal pain by degree of relative weight change in the SOS intervention study. Incidence and recovery proportions are unadjusted, _P_-values are adjusted for age, smoking, working status and physical activity. ***P<0.001, **P<0.01, *P<0.05, (*)P<0.10. The upper panel shows the 2-year follow-up and the lower panel the 6-year follow-up.
4 Discussion
This study confirms previous reports of an increased risk of musculoskeletal pain in obese subjects compared with the general population. Furthermore, the frequency of musculoskeletal pain was reduced after obesity surgery as compared to conventional obesity treatment.
Obese and overweight individuals face an increased risk of musculoskeletal pain (Hellsing and Bryngelsson, 2000; Leboeuf-Yde et al., 1999; Miranda et al., 2001; Quesenberry et al., 1998) and osteoarthritis (Felson et al., 2000). Obese subjects overload their knee and hip joints, which probably explains most of the increased risk of developing osteoarthritis (Felson et al., 2000). However, there are data showing an increased risk of osteoarthritis of the hand in the obese, suggesting that some metabolic and/or genetic factor may partially account for the obesity–osteoarthritis relationship (Oliveria et al., 1999).
Leboeuf-Yde et al., 1999 discussed the more sedentary lifestyle of overweight individuals as an explanation for the increased risk of having musculoskeletal pain in the lower back. Mental distress and physically strenuous work also increase the risk of musculoskeletal pain (Miranda et al., 2001). It is noteworthy that obese subjects run an increased risk of poor mental well-being (Sullivan et al., 2001) and that obesity is more common in lower socio-economic strata (Lissner, 1997). Negative psychosocial stress has also been discussed as a cornerstone in the pathophysiology of obesity and the metabolic syndrome (Björntorp, 1993). There are studies that have investigated pain sensitivity thresholds in relation to obesity. Most, but not all, indicate that obese subjects have increased pain thresholds (Khimich, 1997; McKendall and Haier, 1983; Pradalier et al., 1981; Raymond et al., 1995; Zahorska-Markiewicz et al., 1983; Zahorska-Markiewicz et al., 1988).
A marked gender difference in the prevalence of musculoskeletal pain – women have problems more frequently – has been reported previously (Rollman and Lautenbacher, 2001). Different exposures to work environment risks, different muscle strength and psychosocial factors have been discussed (Fredriksson et al., 1999; Leijon et al., 1998; Nordander et al., 1999). Women are also more sensitive to pain and have a diminished pressure pain threshold (Rollman and Lautenbacher, 2001; Wise et al., 2002).
Surgical obesity treatment has beneficial effects on cardiovascular risk factors (Sjöström et al., 1999), cardiac structure and function (Karason et al., 1997, 1998), the incidence of diabetes (Pories et al., 1995; Sjöström et al., 1999), health-related quality of life (Karlsson et al., 1998) and some aspects of health economy (Narbro et al., 1999). Surgical complications and adverse outcomes in the SOS study have been reported elsewhere (Sjöström, 2000; Torgerson et al., 2002).
A reduced incidence of, as well as an increased recovery from, work-restricting musculoskeletal pain in the present study clearly represents another advantage of obesity surgery. These positive effects were related to the degree of weight change, and maintained over a follow-up period of 6 years. Previously, beneficial effects of obesity surgery on the occurrence of pain in the lower back and hip, knee and ankle joints have been shown in one randomized trial (The Danish Obesity Project, 1979) and in one uncontrolled study of morbidly obese (McGoey et al., 1990). Our study provides additional information on the beneficial effects of obesity surgery on musculoskeletal pain, with a much larger study group and longer follow-up period and by reporting sex-specific incidence and recovery rates. Furthermore, weight loss was associated with a reduced risk of both symptomatic and radiographic knee osteoarthritis in the Framingham Study (Felson et al., 1992, 1997), whereas weight gain correlated with the risk of radiographic knee osteoarthritis (Felson et al., 1997).
Paradoxically, there does not appear to be any reduction in the use of drugs against inflammation and pain in parallel with surgically induced weight loss (Narbro et al., 2002). Still, there are some indications that the drug treatment of overweight, in patients with osteoarthritis of the hip or knee, results in symptomatic relief and reduced consumption of pain killers (Toda et al., 1998; Williams and Foulsham, 1981).
Work-restricting pain in the hip, knee and ankle joints was generally more responsive to weight loss than pain in the neck and back areas. This indicates that pain in these joints is related to osteoarthritis and mechanical overload (Felson et al., 2000). However, we also observed an increased recovery from pain in the neck and back following weight reduction. Apart from mechanical factors, improved mental well-being (Sullivan et al., 2001) and increased physical activity (Karason et al., 2000) in the operated group could also contribute to the observed beneficial effects on pain occurrence.
One general problem when comparing studies of musculoskeletal pain is that different case definitions have been employed (Brattberg et al., 1989; Carey et al., 1996; Cassidy et al., 1998; Leboeuf-Yde et al., 1996). As musculoskeletal pain is common and often transient, it seems reasonable to use a definition that mainly identifies the more severe cases. We used work-restricting musculoskeletal pain in five different body areas during the past 12-month period. It is reasonable to assume that a 12-month limit could diminish recall errors, especially when asking about problems with such a relative impact (Miranda et al., 2001). We have no objective measure of work-restricting pain, e.g. sick leave. Furthermore, we cannot distinguish osteoarthritis from other types of musculoskeletal disorder, which must be remembered when the data are interpreted.
Other limitations of the present study are the relatively low response rate in the cross-sectional study and the non-randomized design of the intervention study. In the cross-sectional study, non-responders had similar sex and age distribution as the responders. Still, as we do not know the pain characteristics of the non-responders, it could be that they were worse off in this respect than the responders. In that case, the excess pain burden in the obese reported here could be an overestimation. The SOS intervention study is not randomized, as such a study design was not approved by the Swedish ethical committees considering the high postoperative mortality in the early 1980s. Instead, the subjects themselves chose a treatment group and a matching procedure was applied to select the controls, aiming to minimize differences in various risk factors between the treatment groups (Sjöström, 2000). Still, there is no guarantee that the two treatment groups are similar regarding factors not included in the matching procedure. Further, the treatment preference might affect outcome in the present study, especially since outcome is determined using self-reported data. Finally, the SOS intervention study is based on a selected group since subjects were self-selected and recruited by advertisements in mass media. Several exclusion criteria were used, i.e. severe illnesses and abuse. Thus, our obese population is probably healthier than the general Swedish obese population. The present results should thus be interpreted with some caution.
On the other hand, the strengths of the study are the use of both cross-sectional and longitudinal data relating to a large cohort of patients (both sexes), covering a wide BMI range. All subjects were examined using identical, standardized techniques. According to the study protocol, both treatment groups received similar attendance during follow-up, except for one extra visit in the operated group 3 months after the surgery.
In conclusion, this study confirms previous results showing an excess burden of musculoskeletal pain in the obese. Further, surgical treatment of severe obesity reduces the long-term risk of developing work-restricting musculoskeletal pain and increases the likelihood of recovering from such pain.
Acknowledgements
The SOS study was supported by the Swedish Research Council (grant number 05239) and by F. Hoffmann-La Roche Ltd.
References
Andersson HI, Ejlertsson G, Leden I, Rosenberg C. Chronic pain in a geographically defined general population: studies of differences in age, gender, social class, and pain localization. Clin J Pain. 1993;9:174-182.
Björntorp P. Visceral obesity: a ‘civilization syndrome’. Obes Res. 1993;1:206-222.
Bovim G, Schrader H, Sand T. Neck pain in the general population. Spine. 1994;19:1307-1309.
Brattberg G, Thorslund M, Wikman A. The prevalence of pain in a general population. The results of a postal survey in a county of Sweden. Pain. 1989;37:215-222.
Carey TS, Evans AT, Hadler NM, Lieberman G, Kalsbeek WD, Jackman AM, Fryer JG, McNutt RA. Acute severe low back pain. A population-based study of prevalence and care-seeking. Spine. 1996;21:339-344.
Cassidy JD, Carroll LJ, Cote P. The Saskatchewan health and back pain survey. The prevalence of low back pain and related disability in Saskatchewan adults. Spine. 1998;23:1860-1866. (discussion p. 1867).
Felson DT, Lawrence RC, Dieppe PA, Hirsch R, Helmick CG, Jordan JM, Kington RS, Lane NE, Nevitt MC, Zhang Y, Sowers M, McAlindon T, Spector TD, Poole AR, Yanovski SZ, Ateshian G, Sharma L, Buckwalter JA, Brandt KD, Fries JF. Osteoarthritis: new insights. Part 1: the disease and its risk factors. Ann Intern Med. 2000;133:635-646.
Felson DT, Zhang Y, Anthony JM, Naimark A, Anderson JJ. Weight loss reduces the risk for symptomatic knee osteoarthritis in women. The Framingham study. Ann Intern Med. 1992;116:535-539.
Felson DT, Zhang Y, Hannan MT, Naimark A, Weissman B, Aliabadi P, Levy D. Risk factors for incident radiographic knee osteoarthritis in the elderly: the Framingham study. Arthritis Rheum. 1997;40:728-733.
Fredriksson K, Alfredsson L, Koster M, Thorbjornsson CB, Toomingas A, Torgen M, Kilbom A. Risk factors for neck and upper limb disorders: results from 24 years of follow up. Occup Environ Med. 1999;56:59-66.
Hellsing AL, Bryngelsson IL. Predictors of musculoskeletal pain in men: a twenty-year follow-up from examination at enlistment. Spine. 2000;25:3080-3086.
Karason K, Wallentin I, Larsson B, Sjöström L. Effects of obesity and weight loss on left ventricular mass and relative wall thickness: survey and intervention study. Br Med J. 1997;315:912-916.
Karason K, Wallentin I, Larsson B, Sjöström L. Effects of obesity and weight loss on cardiac function and valvular performance. Obes Res. 1998;6:422-429.
Karason K, Lindroos AK, Stenlöf K, Sjöström L. Relief of cardiorespiratory symptoms and increased physical activity after surgically induced weight loss: results from the Swedish obese subjects study. Arch Intern Med. 2000;160:1797-1802.
Karlsson J, Sjöström L, Sullivan M. Swedish obese subjects (SOS) – an intervention study of obesity. Two-year follow-up of health-related quality of life (HRQL) and eating behavior after gastric surgery for severe obesity. Int J Obes Relat Metab Disord. 1998;22:113-126.
Khimich S. Level of sensitivity of pain in patients with obesity. Acta Chir Hung. 1997;36:166-167.
Leboeuf-Yde C, Klougart N, Lauritzen T. How common is low back pain in the Nordic population? Data from a recent study on a middle-aged general Danish population and four surveys previously conducted in the Nordic countries. Spine. 1996;21:1518-1525. (discussion p. 1525–6).
Leboeuf-Yde C, Kyvik KO, Bruun NH. Low back pain and lifestyle. Part II – Obesity. Information from a population-based sample of 29,424 twin subjects. Spine. 1999;24:779-783. (discussion p. 783–4).
Leijon M, Hensing G, Alexanderson K. Gender trends in sick-listing with musculoskeletal symptoms in a Swedish county during a period of rapid increase in sickness absence. Scand J Soc Med. 1998;26:204-213.
Linton SJ, Hellsing AL, Hallden K. A population-based study of spinal pain among 35–45-year-old individuals. Prevalence, sick leave, and health care use. Spine. 1998;23:1457-1463.
Lissner L. Psychosocial aspects of obesity: individual and societal perspectives. Scand J Nutr. 1997;41:75-79.
Lissner L, Lindroos AK, Sjöström L. Swedish obese subjects (SOS): an obesity intervention study with a nutritional perspective. Eur J Clin Nutr. 1998;52:316-322.
Mäkelä M, Heliövaara M, Sievers K, Impivaara O, Knekt P, Aromaa A. Prevalence, determinants, and consequences of chronic neck pain in Finland. Am J Epidemiol. 1991;134:1356-1367.
Mäntyselkä P, Kumpusalo E, Ahonen R, Kumpusalo A, Kauhanen J, Viinamäki H, Halonen P, Takala J. Pain as a reason to visit the doctor: a study in Finnish primary health care. Pain. 2001;89:175-180.
McGoey BV, Deitel M, Saplys RJ, Kliman ME. Effect of weight loss on musculoskeletal pain in the morbidly obese. J Bone Joint Surg Br. 1990;72:322-323.
McKendall MJ, Haier RJ. Pain sensitivity and obesity. Psychiatry Res. 1983;8:119-125.
Miranda H, Viikari-Juntura E, Martikainen R, Takala EP, Riihimäki H. A prospective study of work related factors and physical exercise as predictors of shoulder pain. Occup Environ Med. 2001;58:528-534.
Narbro K, Ågren G, Jonsson E, Larsson B, Näslund I, Wedel H, Sjöström L. Sick leave and disability pension before and after treatment for obesity: a report from the Swedish obese subjects (SOS) study. Int J Obes Relat Metab Disord. 1999;23:619-624.
Narbro K, Ågren G, Jonsson E, Näslund I, Sjöström L, Peltonen M. Pharmaceutical costs in obese individuals: comparison with a randomly selected population sample and long-term changes after conventional and surgical treatment: the SOS intervention study. Arch Intern Med. 2002;162:2061-2069.
Nordander C, Ohlsson K, Balogh I, Rylander L, Pålsson B, Skerfving S. Fish processing work: the impact of two sex dependent exposure profiles on musculoskeletal health. Occup Environ Med. 1999;56:256-264.
Oliveria SA, Felson DT, Cirillo PA, Reed JI, Walker AM. Body weight, body mass index, and incident symptomatic osteoarthritis of the hand, hip, and knee. Epidemiology. 1999;10:161-166.
Pories WJ, Swanson MS, MacDonald KG, Long SB, Morris PG, Brown BM, Barakat HA, deRamon RA, Israel G, Dolezal JM, Dohm L. Who would have thought it? An operation proves to be the most effective therapy for adult-onset diabetes mellitus. Ann Surg. 1995;222:339-350. (discussion p. 350–2).
Pradalier A, Willer JC, Boureau F, Dry J. Relationship between pain and obesity: an electrophysiological study. Physiol Behav. 1981;27:961-964.
Quesenberry CP Jr, Caan B, Jacobson A. Obesity, health services use, and health care costs among members of a health maintenance organization. Arch Intern Med. 1998;158:466-472.
Raymond NC, de Zwaan M, Faris PL, Nugent SM, Achard DM, Crosby RD, Mitchell JE. Pain thresholds in obese binge-eating disorder subjects. Biol Psychiatry. 1995;37:202-204.
Rollman GB, Lautenbacher S. Sex differences in musculoskeletal pain. Clin J Pain. 2001;17:20-24.
Sjöström CD, Lissner L, Wedel H, Sjöström L. Reduction in incidence of diabetes, hypertension and lipid disturbances after intentional weight loss induced by bariatric surgery: the SOS intervention study. Obes Res. 1999;7:477-484.
Sjöström L. Surgical intervention as a strategy for treatment of obesity. Endocrine. 2000;13:213-230.
Sjöström L, Larsson B, Backman L, Bengtsson C, Bouchard C, Dahlgren S, Hallgren P, Jonsson E, Karlsson J, Lapidus L, Lindroos AK, Lindstedt S, Lissner L, Narbro K, Näslund I, Olbe L, Sullivan M, Sylvan A, Wedel H, Ågren G. Swedish obese subjects (SOS). Recruitment for an intervention study and a selected description of the obese state. Int J Obesity. 1992;16:465-479.
StataCorp, Stata Statistical Software: Release 7.0, Stata Corporation, College Station, TX, 2001.
Sullivan M, Karlsson J, Sjöström L, Taft C., 2001. Why quality of life measures should be used in the treatment of patients with obesity. In: Björntorp P, editor., International textbook of obesity. Wiley, New York, NY, pp. 485-510.
The Danish Obesity Project. Randomised trial of jejunoileal bypass versus medical treatment in morbid obesity. Lancet. 1979;2:1255-1258.
Toda Y, Toda T, Takemura S, Wada T, Morimoto T, Ogawa R. Change in body fat, but not body weight or metabolic correlates of obesity, is related to symptomatic relief of obese patients with knee osteoarthritis after a weight control program. J Rheumatol. 1998;25:2181-2186.
Torgerson JS, Lindroos AK, Näslund I, Peltonen M. Gallstones, gallbladder disease and pancreatitis. Cross sectional and two-year data from the Swedish Obese Subjects (SOS) and SOS reference studies. Am J Gastroenterol 2003. (in press).
van der Windt DA, Thomas E, Pope DP, de Winter AF, Macfarlane GJ, Bouter LM, Silman AJ. Occupational risk factors for shoulder pain: a systematic review. Occup Environ Med. 2000;57:433-442.
WHO., 2000. Obesity: preventing and managing the global epidemic, WHO, Geneva.
Williams RA, Foulsham BM. Weight reduction in osteoarthritis using phentermine. Practitioner. 1981;225:231-232.
Wise EA, Price DD, Myers CD, Heft MW, Robinson ME. Gender role expectations of pain: relationship to experimental pain perception. Pain. 2002;96:335-342.
Zahorska-Markiewicz B, Kucio C, Pyszkowska J. Obesity and pain. Hum Nutr Clin Nutr. 1983;37:307-310.
Zahorska-Markiewicz B, Zych P, Kucio C. Pain sensitivity in obesity. Acta Physiol Pol. 1988;39:183-187.
Keywords:
Musculoskeletal pain; Obesity; Weight loss; Incidence; Recovery
© 2003 Lippincott Williams & Wilkins, Inc.