LAUSR

Objectives We aimed to investigate age- and sex-specific effects of obesity, metabolic syndrome (MetS) and its components on back pain in middle-aged and older English individuals. Methods We used data from the English Longitudinal Study of Ageing, wave 2 (2004-2005). Body mass index (BMI) expressed the obesity, while MetS was defined according to revised Adult Treatment Panel (ATP) III criteria. We assessed associations between obesity, MetS and its components with presence and severity of back pain and provided estimates per strata, middle-aged (50-64 years) and older (65-79 years), women and men. Results The study sample included 3328 participants, 1021 and 835 middle-aged women and men and 773 and 699 older women and men, respectively. We found that BMI (OR=1.07, 95% CI 1.05-1.09), MetS (OR=1.47, 95% CI 1.22-1.77), high waist circumference (WC), high triglycerides (TG), and high fasting blood glucose were associated with the presence of back pain. Effects of BMI were consistent across the strata. However, MetS was associated with back pain only in women, middle-aged (OR=1.59, 95% CI 1.14-2.21) and older (OR=1.43, 95% CI 1.01-2.05). The MetS component driving this association was high WC, supported by high TG in older women. Higher BMI, presence of MetS, high blood pressure and TG were associated with back pain severity. Conclusions We found that obesity was associated with the presence and severity of back pain, irrespective of age and sex. However, we found women-specific effects of MetS driven by high WC, indicating that metabolic dysregulation contributes to back pain pathophysiology in women.