Residential Greenness and Frailty Among Older Adults: A Longitudinal Cohort in China

OBJECTIVES: Frailty is an accumulation of deficits characterized by reduced resilience to stressors and increased vulnerability to adverse outcomes. There is evolving evidence on the health benefits of residential greenness, but little is known about its impact on frailty. DESIGN: A longitudinal cohort study. SETTING AND PARTICIPANTS: We included older adults aged ≥65 years from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) with a 12-year follow-up. METHODS: We assessed residential greenness by calculating the Normalized Difference Vegetation Index (NDVI) in the 500 m radius around participants' residence. We used 39 self-reported health items to construct a frailty index (FI) as a proportion of accumulated deficits. We defined an FI of ≤0.21 as nonfrail and prefrail, and an FI of >0.21 as frail. We used the mixed effects logistic regression models to examine the association between residential greenness and frailty, adjusted for a number of covariates. RESULTS: We had 16,238 participants, with a mean age of 83.0 years (standard deviation: 11.5). The mean baseline NDVI and FI were 0.40, and 0.12, respectively. Compared to the participants living in the lowest quartile of residential greenness, those in the highest quartile had a 14% [odds ratio (OR): 0.86, 95% confidence interval (CI): 0.77, 0.97] lower odds of frailty. The association was stronger among urban vs rural residents. Additionally, each 0.1-unit increase in annual average NDVI was related to a 2% higher odds of improvement in the frailty status (OR: 1.02, 95% CI: 1.00, 1.04). CONCLUSIONS AND IMPLICATIONS: Our study suggests that higher levels of residential greenness are related to a lower likelihood of frailty, specifically in urban areas.