Is living alone a risk factor of frailty? A systematic review and meta-analysis

•Living alone has been considered as social vulnerability.•Information on living alone and frailty is scarce in the literature.•Living alone is cross-sectionally associated with physical frailty.•Men living alone are more likely to be frail while women are not.•No significant longitudinal association is observed. To examine the association of living alone with frailty in cross-sectional and longitudinal studies by a systematic review and meta-analysis. Systematic review and meta-analysis. Community-dwelling older adults with a mean age of >60 years. A systematic search of the literature was conducted according to the PRISMA guidelines. We searched PubMed in February 2019 without language restriction for cohort studies that examined the associations between living alone and frailty. The reference lists of the relevant articles and the included articles were reviewed for additional studies. We calculated pooled odds ratios (OR) of the presence and incidence of frailty for living alone from cross-sectional and longitudinal studies. Among the 203 studies identified, data of 44 cross-sectional studies (46 cohorts) and 6 longitudinal studies were included in this review. The meta-analysis showed that older adults living alone were more likely to be frail than those who were not (46 cohorts: pooled OR = 1.28, 95 % confidence interval (CI) = 1.13–1.45, p < 0.001). Gender-stratified analysis showed that only men living alone were at an increased risk of being frail (20 cohorts: pooled OR = 1.71, 95 %CI = 1.49–1.96), while women were not (22 cohorts: pooled OR = 1.00, 95 %CI = 0.83–1.20). No significant association was observed in a meta-analysis of longitudinal studies (6 cohorts: pooled OR = 0.88, 95 %CI = 0.76–1.03). The present systematic review and meta-analysis showed a significant cross-sectional association between living alone and frailty, especially in men. However, living alone did not predict incident frailty. More studies controlling for important confounders, such as social networks, are needed to further enhance our understanding of how living alone is associated with frailty among older adults.