Daily Steps and Mortality

Summary

A prospective cohort study 1 (part of the Coronary Artery Risk Development in Young Adults, CARDIA study) included a total of 2 110 subjects with a mean age of 45.2 years, and with a mean follow-up of 10.8 years.

The CARDIA study included 5 115 adults aged 18 to 30 years at baseline in 1985 to 1986. The study recruited a balanced sample by race (Black and White), sex, age, and education from 4 US locations. At the year 20 (2005-2006) follow-up examination (retention rate among surviving participants 72% and cohort age 38 to 50 years), 2 332 participants wore an accelerometer for 7 consecutive days during all waking hours.

Daily steps volume was classified as low (<7 000 steps/day), moderate (7 000-9 999 steps/day), and high (≥10 000 steps/day). Significantly greater proportion of women (62.5%) and Black participants (53.8%) were in the lowest step group (p < 0.001). Participants in the low step group had higher BMI, lower self-rated health, and higher prevalence of stage 2 hypertension and diabetes than the moderate and high step volume groups.

Using multivariable adjusted Cox proportional hazards models, compared with participants in the low step group, there was significantly lower risk of mortality in the moderate (HR 0.28, 95% CI 0.15 to 0.54; RD 53, 95% CI 27 to 78 events per 1000 people) and high (HR 0.45, 95% CI 0.25 to 0.81; RD 41, 95% CI 15 to 68 events per 1000 people) step groups.

In race-specific analysis, high step rates were associated with reduced risk among Black participants (HR 0.30, 95% CI 0.14 to 0.63) and White participants (HR 0.37, 95% CI 0.17 to 0.81) compared with participants in the low step group. In sex-specific analysis high step rates were associated with reduced risk for women (HR 0.28, 95% CI 0.12 to 0.63) and men (HR 0.42, 95% CI 0.20 to 0.88) compared with participants in the low step group.