Cross-sectional association of residential greenness exposure with activities of daily living disability among urban elderly in Shanghai

Residential greenness exposure is associated with many health outcomes, including obesity, cardiovascular disease, and mental disorders. However, few studies have assessed the effects of greenness exposure on activities of daily living (ADL). This study evaluated the relationship between greenness and ADL among elderly residents with long-term care insurance (LTCI) in Shanghai, China.We conducted a cross-sectional survey using stratified random sampling among elderly residents with LTCI in six districts of Shanghai in August 2018. We quantitatively assessed residential greenness using satellite-derived normalized difference vegetation index (NDVI) values with 250-, 500-, and 1000-m buffers around each participant's residential address. We calculated the walk score to assess neighborhood walkability. Physical function was assessed using basic ADL (BADL) and instrumental ADL (IADL). We performed binary logistic regression and restricted cubic splines with R software.The study participants were 1067 adults with a mean age of 82.40 years (standard deviation, 7.68 years). The mean NDVI value was 0.311. In the fully adjusted model, being in the highest-tertile NDVI500-m had a significant protective effect on BADL mild to none disability (odds ratio, 2.143; 95% confidence interval, 1.489-3.084) compared with participants in the lowest-tertile NDVI500-m. Restricted cubic spline showed a non-linearity association between NDVI values and BADL and IADL mild to none disability.Our results indicate the importance of residential greenness exposure to physical function-especially for BADL disability. Well-designed longitudinal studies are needed to confirm our findings and investigate the underlying mechanisms.