Association Of Steps Per Day With Premature Mortality: RESULTS From The Cardia Study

Abstract

PURPOSE: The 2018 Physical Activity Guidelines Advisory Committee Report calls for research to examine associations of step volume with long-term clinical endpoints, including mortality. To date, there are few prospective studies examining accelerometer-measured steps/day with mortality. METHODS: Data are from 2027 participants from the Coronary Artery Risk Development in Young Adults (CARDIA) study with valid (≥4 days, ≥10 hours/day) accelerometer wear (ActiGraph 7164) at the year 20 exam (2005-2006). Multivariable Cox models calculated hazard ratios (HR) and 95% confidence intervals (CI) for mortality for the total sample and by race and sex. RESULTS: The sample (45.3±3.6 years; 58% women, 41% black) had mean follow-up time of 10.8±0.9 years, and 67 total deaths occurred. The participants had a median [IQR] of 10004 [8061-12097] steps/day according to the raw output and 6670 [4987-8617] steps/day when applying a censoring equation omitting steps accumulated at low accelerations of <500 counts/minute. Black women accumulated significantly lower step volume vs. all other race-sex groups (p<0.05). Adjusting for demographics, lifestyle characteristics, and comorbidities, every 1000 higher steps/day was associated with a 10% lower risk of mortality (HR:0.90, 95% CI:0.83, 0.99). When stratifying by race or sex, HRs remained statistically significant for women (HR:0.77, 95%CI:0.66, 0.90) and blacks (HR:0.85, 95%CI:0.76, 0.96). Black women had 28% lower risk of mortality for every 1000 higher steps/day (HR:0.72, 95%CI:0.58, 0.88). CONCLUSIONS: Among this sample of middle-age adults, accumulating a higher volume of steps/day was associated with a lower risk of mortality.