Associations of changes in waist-to-height ratio with all-cause mortality among Chinese older adults: a national cohort study

Background Waist-to-height ratio, as an anthropometric indicator, is considered a valid tool for assessing the health status of older adults. However, little is known about the associations between changes in waist-to-height ratio and all-cause mortality in older adults. The aim of the study was to investigate the association between changes in waist-to-height ratio and all-cause mortality in Chinese older adults. Method This study was based on the Chinese Longitudinal Healthy Longevity Survey from 2011 to 2018, including a sample of 4,065 participants aged 60 years and over. Changes in waist-to-height ratio were divided into quintiles, with waist-to-height ratio-stable group (change less than 0.01) defined as the reference group. Cox proportional hazards models were used to examine the associations between changes in waist-to-height ratio and all-cause mortality, adjusted for covariates including demographic characteristics, health behaviors, and health status. Kaplan–Meier survival curves were used to study the associations between changes in different categories of waist-to-height ratio and all-cause mortality. Results The study documented 1,449 deaths among the 4,065 participants. Changes in waist-to-height ratio were significantly associated with all-cause mortality (adjusted hazard ratio: 0.30, 95% confidence interval: 0.13, 0.68). Compared with participants within waist-to-height ratio-stable group, a decline in waist-to-height ratio of ≥ 0.06 was associated with increased all-cause mortality (adjusted hazard ratio: 1.45; 95% confidence interval: 1.24, 1.71). The Log-rank statistic showed the largest decrease in waist-to-height ratio and the lowest cumulative survival. There was no significant interaction between the study subgroups. Conclusion There was an inverse association between changes in waist-to-height and all-cause mortality. Compared with waist-to-height ratio-stable group, participants who had a decline more than 0.06 in waist-to-height ratio had an increased risk of all-cause mortality. This suggested that changes in waist-to-height ratio may be a simple and effective indicator of mortality risk for older adults.