Multimorbidity, mortality, and physical activity.

OBJECTIVES: Multimorbidity and physical inactivity are individually associated with increased mortality risk, but the possibility for physical activity to moderate the multimorbidity-mortality relationship has yet to be investigated. METHODS: Data from the 1999-2006 NHANES were employed, with 16,091 participants constituting the analytic sample. Participants were followed through 2011, including a median follow-up of 99 months. Physical activity was assessed via self-report with multimorbidity assessed from physician diagnosis. RESULTS: After adjustment, for every 1 morbidity increase, participants had a 23% increased risk of all-cause mortality (HR = 1.23; 95% CI: 1.19-1.28; p < 0.001). Multimorbidity mostly remained associated with all-cause mortality across all levels of physical activity, with the exception of those achieving four times the dose of the government guidelines. DISCUSSION: With the exception of those who engaged in high levels of self-reported physical activity, physical activity had a minimal effect on the multimorbidity-mortality relationship.