Device-measured light-intensity physical activity and mortality: A meta-analysis

Abstract
Introduction
The association of light‐intensity physical activity (LPA) with mortality is poorly understood. This meta‐analysis of cohort studies aimed to examine the dose‐response relationships between daily device‐measured LPA and mortality in adults aged 18 or older and to explore whether the associations were independent of moderate‐to‐vigorous physical activity (MVPA).

Methods
Searches for prospective cohort studies providing effect estimates of daily LPA (exposure) on all‐cause mortality (outcome) were systematically undertaken in electronic databases up to April 30, 2019. Subgroup analyses and meta‐regression analyses with random‐effects models were performed to quantify the dose‐response relationships between daily LPA and mortality. Sensitivity analyses were also conducted to assess the stability of the results.

Results
A total of 11 studies were included in the meta‐analysis. Analyses contained 49 239 individuals (mean age 60.7, SD = 13.6) who were followed up for a mean 6.2 years (2.3‐14.2 years), during which 3669 (7.5%) died. In comparison with the reference group (<3 h/d), the pooled HRs (and 95% CIs) of mortality were 0.71 (0.62‐0.82), 0.68 (0.59‐0.79), 0.56 (0.44‐0.71) for groups 3 to <5 h/d, 5 to <7 h/d, and more than 7 hours a day LPA, respectively. Meta‐regression models indicated that there was a log‐cubic dose‐response relationship between daily LPA and mortality in adults and older people, independent of MVPA.

Conclusions
Time spent in daily LPA was associated with reduced risks of mortality in adults and older people. These data support the inclusion of LPA in the future physical activity guidelines.