#Steps per Day and All-Cause #Mortality in Middle-aged Adultsin the Coronary Artery Risk Development in Young Adults Study

IMPORTANCE Steps per day is a meaningful metric for physical activity promotion in clinical and
population settings. To guide promotion strategies of step goals, it is important to understand the
association of steps with clinical end points, including mortality.

OBJECTIVE To estimate the association of steps per day with premature (age 41-65 years) all-cause
mortality among Black and White men and women.

DESIGN, SETTING, AND PARTICIPANTS This prospective cohort study was part of the Coronary
Artery Risk Development in Young Adults (CARDIA) study. Participants were aged 38 to 50 years and
wore an accelerometer from 2005 to 2006. Participants were followed for a mean (SD) of 10.8 (0.9)
years. Data were analyzed in 2020 and 2021.

EXPOSURE Daily steps volume, classified as low (<7000 steps/d), moderate (7000-9999 steps/d),
and high (10 000 steps/d) and stepping intensity, classified as peak 30-minute stepping rate and
time spent at 100 steps/min or more.

RESULTS A total of 2110 participants from the CARDIA study were included, with a mean (SD) age of
45.2 (3.6) years, 1205 (57.1%) women, 888 (42.1%) Black participants, and a median (interquartile
range [IQR]) of 9146 (7307-11 162) steps/d. During 22 845 person years of follow-up, 72 participants
(3.4%) died. 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
(hazard ratio [HR], 0.28 [95% CI, 0.15-0.54]; risk difference [RD], 53 [95% CI, 27-78] events per
1000 people) and high (HR, 0.45 [95% CI, 0.25-0.81]; RD, 41 [95% CI, 15-68] events per 1000
people) step groups. Compared with the low step group, moderate/high step rate was associated
with reduced risk of mortality in Black participants (HR, 0.30 [95% CI, 0.14-0.63]) and in White
participants (HR, 0.37 [95% CI, 0.17-0.81]). Similarly, compared with the low step group, moderate/
high step rate was associated with reduce risk of mortality in women (HR, 0.28 [95% CI, 0.12-0.63])
and men (HR, 0.42 [95% CI, 0.20-0.88]). There was no significant association between peak
30-minute intensity (lowest vs highest tertile: HR, 0.98 [95% CI, 0.54-1.77]) or time at 100 steps/min
or more (lowest vs highest tertile: HR, 1.38 [95% CI, 0.73-2.61]) with risk of mortality.

CONCLUSIONS AND RELEVANCE This cohort study found that among Black and White men and
women in middle adulthood, participants who took approximately 7000 steps/d or more
experienced lower mortality rates compared with participants taking fewer than 7000 steps/d.
There was no association of step intensity with mortality