Background Low back pain (LBP) and obesity are both major public health problems. Obesity has been linked with LBP, with recent studies reporting that increased fat but not lean tissue mass is associated with LBP, however previous studies predominantly examined women. The relationship between body composition and LBP in men is unknown.
Objectives The aim of this study was to examine the relationship between body composition and LBP and disability in a population-based sample of men.
Methods 978 male participants from the Geelong Osteoporosis Study (GOS), a population-based Australian study designed to investigate the epidemiology of osteoporosis among adults, were invited to participate in a follow up study in 2006. Participants completed questionnaires on sociodemographics and health status. LBP was determined using the validated Chronic Back Pain Grade Questionnaire and the presence of mood disorders was assessed using the Hospital Anxiety Depression Scale. Body composition was measured using dual energy x-ray absorptiometry. Independent samples t-tests and chi-square tests were used to compare the baseline characteristics of men with and without LBP and/or disability. Estimated marginal means were used to examine the relationships between obesity measures and body composition in participants with high intensity pain and disability compared to those with no or low pain and disability. Multivariate analyses included adjustments for age, mood disorder, education, mobility and body mass index (BMI). To examine the multivariate associations between body composition and back pain, adjustment was also made for the alternate body composition measure. Interactions between risk factors for LBP and measures of obesity, including measures of body composition were examined.
Results Of the 820 respondents (84% response rate), 124 (15%) had high intensity LBP and/or disability. Participants with high intensity pain and/or disability were older, more likely to have a mood disorder, less likely to have completed secondary school and more likely to have poor mobility than those with no or LBP and disability (p<0.002 for all). LBP was associated with higher BMI (28.7±0.4 vs 27.3±0.2 kg/m2, p=0.02) and waist-hip ratio (0.97±0.006 vs 0.96±0.006, p=0.04), with increased tendency towards having a higher fat mass index (8.0 vs 7.6 kg/m2, p=0.08), but not fat-free mass index (p=0.68). The associations between LBP and measures of obesity were stronger in those with a mood disorder, particularly for waist-hip ratio (p=0.05 for interaction) and fat mass index (p=0.06 for interaction).
Conclusions In a population-based sample of men, high intensity LBP and/or disability were associated with increased levels of obesity, particularly in those with mood disorders. This provides evidence to support a biopsychosocial interaction between mood disorders and obesity with LBP.
Acknowledgement S.B: NHMRC Postgraduate Scholarship, S.BO: Alfred Deakin Postdoctoral Fellowship, D.M.U & A.E.W: NHMRC Career Development Fellowships, A.T: NHMRC Early Career Fellowship, JP: NHMRC grants, GOS: NHMRC grants.
Disclosure of Interest None declared