App-Recorded Daily Step Counts, Sex Differences, and Risk of Cardiovascular Outcomes Among Middle-Aged Population.

Background: Limited data are available on sex-specific associations between daily step counts and cardiovascular events in middle-aged adults.

Methods: This study used the KenCoM Healthcare Database to evaluate sex-specific differences in cardiovascular event risk associated with daily step counts (DSC). The database incorporates DSC data from the KenCoM smartphone app, along with health checkup records and Japanese health insurance claims data. We recruited and enrolled participants using the KenCoM app, registering them in our database between January 2016 and September 2021. The primary outcome was the 5-year cumulative incidence of composite cardiovascular events, including myocardial infarction, stroke, angina pectoris, heart failure, and atrial fibrillation. We compared event rates across quintiles of DSC. The quintiles were defined as follows: Group 1 (<4000 steps/d), Group 2 (4000-5999 steps/d), Group 3 (6000-7999 steps/d), Group 4 (8000-9999 steps/d), and Group 5 (≥10 000 steps/d).

Results: This study included 73 975 participants (55 612 men and 18 363 women) with a mean age of 44.1±10.1 years. The adjusted risk of 5-year cardiovascular events was significantly lower in Group 5 compared with Group 1 in the entire cohort (adjusted hazard ratio, 0.87 [95% CI, 0.77-0.98]; P=0.02). Sex-specific analysis showed that the adjusted risk of cardiovascular events was significantly lower in Group 5 compared with Group 1 in men (adjusted hazard ratio, 0.82 [95% CI, 0.72-0.94]; P=0.004), but this effect was not observed in women.

Conclusions: The highest DSC was associated with a lower risk of cardiovascular events compared with the lowest DSC in men, but not in women, within a middle-aged population.