Development and Testing of an Integrated Score for Physical Behaviors

Purpose Interest in a variety of physical behaviors (e.g., exercise, sitting time, sleep) in relation to health outcomes creates a need for new statistical approaches to analyze the joint effects of these distinct but inter-related physical behaviors. We developed and tested an integrated physical behavior score (PBS). Methods NIH-AARP Diet and Health Study participants (N=163,016) completed a questionnaire (2004-2006) asking about time spent in five exercise and non-exercise physical activities, two sedentary behaviors (television and non-television), and sleep. In half of the sample, we used shape constrained additive regression to model the relationship between each behavior and survival. Maximum logit scores from each of the eight behavior-survival functions were summed to produce a PBS that was proportionally rescaled to range from 0-100. We examined predictive validity of the PBS in the other half-sample using Cox Proportional Hazards models after adjustment for covariates for all-cause and cause-specific mortality. Results In the testing sample, over an average of 6.6y of follow-up, 8,732 deaths occurred. We found a strong graded decline in risk of all-cause mortality across quintiles of PBS (Q5 vs Q1 hazard ratio [95%CI] = 0.53 [0.49, 0.57]). Risk estimates for the PBS were higher than any of the components in isolation. Results were similar but stronger for cardiovascular disease (Q5 vs Q1 = 0.42 [0.39, 0.48]) and other mortality (Q5 vs Q1 = 0.42 [0.36, 0.48]). The relationship between PBS and mortality was observed in stratified analyses by median age, sex, BMI and health status. Conclusions We developed a novel statistical method generated a composite physical behavior that is predictive of mortality outcomes. Future research is needed to test this approach in an independent sample. Corresponding author: Sarah Kozey Keadle, 1 Grand Ave, San Luis Obispo, CA 93407, 805-756-1785 (phone), 805-756-7273 (fax), skeadle@calpoly.edu (email) This work was supported by National Cancer Institute (U01-CA057030 to R.J.C), and the Intramural Research Program at the National Institutes of Health (C.E.M). The funders had no role in the study design; collection, analysis, and interpretation of data; writing the report; and the decision to submit the report for publication. The results of the present study do not constitute an endorsement by ACSM. The results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation and the authors declare no conflicts of interest. Accepted for Publication: 15 February 2019 © 2019 American College of Sports Medicine

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