Instrumented measures of sedentary behaviour and physical activity are associated with mortality in community-dwelling older adults: A systematic review, meta-analysis and meta-regression analysis

•High instrumented sedentary behaviour (i-SB) and low instrumented physical activity (i-PA) are associated with a higher mortality risk.•Adjustments for relatively higher or lower levels of i-PA for i-SB or i-PA, respectively, attenuated these associations.•The highest mortality risk for i-PA was found for total i-PA, suggesting all physical activity levels contribute to lowering mortality risk. Sedentary behaviour (SB) and physical activity (PA) can be objectively assessed with inertial sensors to describe bodily movement. Higher SB and lower PA is associated with higher chronological age and negative health outcomes. This study aimed to quantify the association between instrumented measures of SB (i-SB) and PA (i-PA) and mortality in community-dwelling older adults, to subsequently compare the quantitative effect sizes and to determine the dose-response relationships. An electronic search in six databases from inception to 27th of June 2019 was conducted. All articles reporting on i-SB or i-PA and mortality in community-dwelling older adults aged 60 years or older were considered eligible. A meta-analysis was conducted for the association between i-SB and i-PA and mortality expressed in Hazard Ratios (HR) and 95% Confidence Intervals (95% CI). A meta-regression analysis was performed to determine the dose-response relationship between i-SB and steps per day and mortality. Twelve prospective articles representing eleven cohorts, reporting data of 38,141 participants were included. In total 2502 (6.4%) participants died during follow-up (2.0 to 9.8 years). Comparing the most sedentary with the least sedentary groups of participants resulted in a pooled HR of 2.44 (95% CI 1.82–3.25). Comparing the least active with the most active groups of participants resulted in a pooled HR of 1.93 (95% CI 1.39-2.69); 2.66 (95% CI 2.11–3.35); 3.43 (95% CI 2.61–4.52), and 3.09 (95% CI 2.33–4.11) for light, moderate-to-vigorous-, total PA and steps per day, respectively. Meta-regression analyses showed clear dose-response relationships between i-SB and steps per day and mortality risk. Both i-SB and i-PA are significantly associated with mortality in community-dwelling older adults, showing the largest effect size for total physical activity. Dose-response relationships could be observed for i-SB and steps per day.