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

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 30 April 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 3,669 (7.5%) died. In comparison with the reference group (< 3 hours/day), 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 - < 5 hours/day, 5 - < 7 hours/day, 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.