NHANES 2011-2014: Objective Physical Activity is the Strongest Predictor of All-Cause Mortality

Objectively measured physical activity (PA) is a modifiable risk factor for mortality. Understanding the predictive performance of PA is essential to establish potential targets for early intervention to reduce mortality among older adults. The study used a subset of the National Health and Nutrition Examination Survey (NHANES) 2011-2014 data consisting of participants aged 50 to 80 years old (n = 3653, 24297.5 person-years of follow-up, 416 deaths). Eight accelerometry derived features and 14 traditional predictors of all-cause mortality were compared and ranked in terms of their individual and combined predictive performance using the 10-fold cross-validated Concordance (C) from Cox regression. The top three predictors of mortality in univariate analysis were PA related: average MIMS in the 10 most active hours (C = 0.697), total MIMS per day (C = 0.686), and average log transformed MIMS in the most 10 active hours of the day (C = 0.684), outperforming age (C = 0.676) and other traditional predictors of mortality. In multivariate regression, adding objectively measured PA to the top performing model without PA variables increased concordance from C = 0.776 to C = 0.790 (p < 0.001). These findings highlight the importance of PA as a risk marker of mortality and are consistent with prior studies, confirming the importance of accelerometer-derived activity measures beyond total volume.