Abstract
OBJECTIVES: To determine the extent to which bodily pain mediates the effect of obesity on disability and physical function. DESIGN: Cross-sectional analysis. SETTING: Population-based sample of residents in the greater Boston area. PARTICIPANTS: Community-dwelling adults aged 70 and older (N=736). MEASUREMENTS: Body mass index (BMI), obtained from measured height and weight, was categorized as normal weight (19.0-24.9 kg/m2), overweight (25.0-29.9 kg/m2), or obese (≥30.0 kg/m2). Main outcome measures were the Physical Component Summary of the Medical Outcomes Study 12-item Short-Form Survey (PCS), activity of daily living (ADL) disability, and Short Physical Performance Battery (SPPB) score. Chronic pain was assessed according to the number of weight-bearing joint sites that had pain (hips, knees, feet and pain all over). RESULTS: Older obese adults had greater ADL disability and lower SPPB and PCS scores than their nonobese counterparts, although in sex-stratified adjusted analyses, obesity was adversely associated with outcomes only in women. Obesity was associated with greater number of pain sites; and more pain sites were associated with greater odds of disability. Mediation analysis suggests that pain is a significant mediator (22-44%) of the adverse effect of obesity on disability and physical function in women. CONCLUSION: Bodily pain may be an important treatable mediator of the adverse effect of obesity on disability and physical function in women.