Purpose: Recent cross-sectional findings suggest that co-occurring obesity and psychological problems amplify the risk of disability, but longitudinal evidence is lacking. We assessed this effect in a longitudinal cohort of adults.
Methods: Twelve years of data (1994/1995-2006/2007) were obtained from the Canadian National Population Health Survey. This study followed 8,062 adults that were interviewed every 2 years. Disability status was derived from the Health Utility Index Mark 3. Covariates of interest were repeated psychological distress (Kessler K6 scale) and obesity (body mass index ≥30). Incidence of disability was estimated from Cox proportional hazards models, adjusting for sociodemographic and health variables. Hazard rate of disability in those with either obesity (n = 955) or distress (n = 1,044), or both (n = 138) were compared to those without (n = 5,925).
Results: Participants with both obesity and repeated distress had double the risk of disability compared to those with obesity or distress alone {adjusted hazard ratio of 2.8 [95% confidence interval (CI) 1.8, 4.5] compared to 1.4 (CI 1.1, 1.8) and 1.8 (CI 1.4, 2.3), respectively}.
Conclusions: Recurrent psychological distress combined with obesity amplified the risk for disability normally associated with these conditions.