Daily steps and all-cause mortality: a meta-analysis of 15 international cohorts.
Level 3 - non-randomized controlled study
Meta-analysis of prospective observational cohort studies.
PubMed 35247352 · doi:10.1016/S2468-2667(21)00302-9
What was done
Investigators conducted a meta-analysis of 15 international cohort studies (7 published, 8 unpublished) evaluating the association between daily step count and all-cause mortality in adults aged 18 years and older. Investigators processed participant-level data using a standardised protocol. Cox proportional hazards regression analyses estimated hazard ratios (HRs) across study-specific step-count quartiles and stepping rates using inverse-variance weighted random effects models, with dose-response shapes evaluated using restricted cubic splines.
What was found
Across 47,471 adults followed for a median of 7.1 years (297,837 person-years; 3,013 deaths), median step counts were 3,553 for quartile 1, 5,801 for quartile 2, 7,842 for quartile 3, and 10,901 for quartile 4. Compared with quartile 1, adjusted HRs for mortality were 0.60 (95% CI 0.51-0.71) for quartile 2, 0.55 (0.49-0.62) for quartile 3, and 0.47 (0.39-0.57) for quartile 4. Mortality risk plateaued at 6,000-8,000 steps per day for adults aged 60 and older, and at 8,000-10,000 steps per day for adults younger than 60. Adjusting for step volume, mortality associations remained significant for peak 30-min cadence (HR 0.67 [0.56-0.83]) and peak 60-min cadence (HR 0.67 [0.50-0.90]), but not for daily time spent at 40 or more steps/min (HR 1.12 [0.96-1.32]) or 100 or more steps/min (HR 0.86 [0.58-1.28]).
Why it matters
These findings challenge the universal recommendation of 10,000 steps per day by showing substantial mortality risk reductions level off at lower thresholds, particularly for older adults.
Limits
The observational nature of the included cohorts leaves potential for residual confounding and reverse causality. Step counts were measured at baseline only, precluding assessment of changes in activity over time.