Association of obesity, physical performance and mental health status with low back pain: a prospective cohort study

Abstract

Purpose: While obesity, physical performance and mental health are associated with low back pain (LBP), our understanding of the inter-relationship between these factors is limited. This study examined the associations of 1) obesity and physical performance with LBP; and 2) obesity and mental health status with LBP in community-based adults. Methods: A total of 5058 participants (56% women) of the Australian Diabetes, Obesity and Lifestyle Study (AusDiab) were assessed at baseline (1999-2000) for obesity (BMI >30 kg/m2), physical performance using the physical health component summary (PCS) score of Short Form 36 (SF-36) and mental health using the mental health component summary (MCS) score of the SF-36. At follow-up (2013-2014) LBP was assessed using the Chronic Pain Grade Questionnaire. Based on the presence of obesity and significantly impaired physical performance (defined as the lowest 25% of PCS score), participants were categorised into the following groups: (i) no obesity and normal physical performance; (ii) obesity and normal physical performance; (iii) no obesity and impaired physical performance and (iv) obesity and impaired physical performance. Similarly, based on the presence of obesity and significantly impaired mental health (defined as the lowest 25% of MCS score), participants were categorised into the following groups: (i) no obesity and normal mental health; (ii) obesity and normal mental health; (iii) no obesity and impaired mental health and (iv) obesity and impaired mental health. Binary logistic regressions were used to estimate the odds ratio for LBP intensity associated with obesity and physical performance; and obesity and mental health. All the analyses were adjusted for age, smoking, socioeconomic status, physical activity and mental component score. Results: 20% of participants reported high intensity LBP, of whom 60% were women. Using women with neither obesity nor significantly impaired physical performance as the reference group, women with both obesity and significantly impaired physical performance had a higher prevalence of high intensity LBP (OR 4.69, 95% CI 3.35- 6.58) compared with those with significantly impaired physical performance alone (OR 2.81, 95% CI 2.12- 3.73) or obesity alone (OR 1.55, 95% CI 1.17- 2.05). In men, those with obesity and significantly impaired physical performance had a higher prevalence of high intensity LBP (OR 4.38, 95% CI 2.78-6.90) compared to significantly impaired physical performance alone (OR 2.45, 95% CI 1.76-3.42). Using women with neither obesity nor impaired mental health as the reference group, women with both obesity and impaired mental health had a higher risk of high intensity LBP (OR 3.08, 95% CI 2.15-4.40) compared to those with significantly impaired mental health only (OR 1.93, 95% CI 1.5- 2.48) or obesity only (OR 1.59, 95% CI 1.20- 2.09). In men, the risk of high intensity LBP was similar in those with obesity and significantly impaired mental health (OR 1.73, 95% CI 1.08- 2.77) and those with significantly impaired mental health alone (OR 1.53, 95% CI 1.13-2.07). Conclusions: Our findings suggest that, along with targeting obesity, strategies aiming to improve physical performance and mental health have the potential to reduce the burden of LBP in community-based adults, particularly in women.