Systematic review of the prospective association of daily step counts with risk of mortality, cardiovascular disease, and dysglycemia

Abstract

Background: Daily step counts is an intuitive metric that has demonstrated success in motivating physical activity in adults and may hold potential for future public health physical activity recommendations. This review seeks to clarify the pattern of the associations between daily steps and subsequent all-cause mortality, cardiovascular disease (CVD) morbidity and mortality, and dysglycemia, as well as the number of daily steps needed for health outcomes.

Methods: A systematic review was conducted to identify prospective studies assessing daily step count measured by pedometer or accelerometer and their associations with all-cause mortality, CVD morbidity or mortality, and dysglycemia (dysglycemia or diabetes incidence, insulin sensitivity, fasting glucose, HbA1c). The search was performed across the Medline, Embase, CINAHL, and the Cochrane Library databases from inception to August 1, 2019. Eligibility criteria included longitudinal design with health outcomes assessed at baseline and subsequent timepoints; defining steps per day as the exposure; reporting all-cause mortality, CVD morbidity or mortality, and/or dysglycemia outcomes; adults ≥18 years old; and non-patient populations.

Results: Seventeen prospective studies involving over 30,000 adults were identified. Five studies reported on all-cause mortality (follow-up time 4-10 years), four on cardiovascular risk or events (6 months to 6 years), and eight on dysglycemia outcomes (3 months to 5 years). For each 1000 daily step count increase at baseline, risk reductions in all-cause mortality (6-36%) and CVD (5-21%) at follow-up were estimated across a subsample of included studies. There was no evidence of significant interaction by age, sex, health conditions or behaviors (e.g., alcohol use, smoking status, diet) among studies that tested for interactions. Studies examining dysglycemia outcomes report inconsistent findings, partially due to heterogeneity across studies of glycemia-related biomarker outcomes, analytic approaches, and sample characteristics.

Conclusions: Evidence from longitudinal data consistently demonstrated that walking an additional 1000 steps per day can help lower the risk of all-cause mortality, and CVD morbidity and mortality in adults, and that health benefits are present below 10,000 steps per day. However, the shape of the dose-response relation is not yet clear. Data are currently lacking to identify a specific minimum threshold of daily step counts needed to obtain overall health benefit.

Keywords: Accelerometer; Diabetes; Physical activity; Physical activity guidelines; Prevention; Public health; Walking.

Fig. 1

Article screening process

Fig. 2

Associations of quantile medians^a of baseline daily step counts and all-cause mortality across included studies. Abbreviations: O:E, ratio of observed and expected deaths, AHR, adjusted hazard ratio; CI, confidence interval; Note: Error bars represent the lower and upper bounds of the 95% confidence interval. ^aQuantile medians of daily step counts at baseline were not reported by Jefferis and colleagues [17]. Therefore, the midpoints of the quantile ranges of daily step counts at baseline were plotted instead. ^bDwyer, 2015 reported the distribution of obeserved and expected deaths (confidence intervals not reported) by quantiles of daily step counts at baseline. Shading on the figure indicates the distinction in measure of association from the other four studies, all of which assessed the associations of quantiles of daily step counts at baseline and the adjusted hazard ratio for all-cause mortality