Association of weight change with all-cause and cause-specific mortality: an age-stratified analysis

Background The associations of weight change with all-cause and cause-specific mortality stratified by age remains unclear. We evaluated the age-stratified (< 65 vs >= 65 years) associations of weight change with all-cause and cause-specific mortality in a large sample of Chinese adults. Methods Our cohort study included 746,991 adults aged at least 45 years from the Shenzhen Healthcare Big Data Cohort in China. BMI change were categorized as change within 5% (stable), decrease by 5% to 10%, decrease by > 10%, increase by 5% to 10%, and increase by > 10%. Cox proportional hazard models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause, non-communicable disease, cardiovascular disease (CVD), and cancer mortality according to BMI change, with adjustment for potential confounders. Results During a median follow-up of 2.2 years (2,330,180 person-years), there were 10,197 deaths. A notable interaction emerged between weight change and age. For participants >= 65 years, compared with stable BMI, more than a 10% decrease in BMI was associated with higher risk of all-cause mortality (HR: 1.69, 95% CI: 1.54-1.86), non-communicable disease mortality (HR: 1.67, 95% CI: 1.52-1.84), CVD mortality (HR: 1.55, 95% CI: 1.34-1.80), and cancer mortality (HR: 1.59, 95% CI: 1.33-1.92). Similar patterns of results for 5% to 10% decrease in BMI were observed. More than a 10% increase in BMI was associated with increased risk of all-cause mortality (HR: 1.13, 95% CI: 1.04-1.24), non-communicable disease mortality (HR: 1.14, 95% CI: 1.04-1.25), and CVD mortality (HR: 1.27, 95% CI: 1.12-1.44). For participants < 65 years, only more than a 10% decrease in BMI was associated with higher risk of all-cause mortality (HR: 1.41, 95% CI: 1.12-1.77), non-communicable disease mortality (HR: 1.43, 95% CI: 1.13-1.81), and cancer mortality (HR: 1.79, 95% CI: 1.29-2.47). Conclusions Weight loss and excessive weight gain were associated with increased risks of mortality among older adults, while only excessive weight loss was associated with increased risks of mortality among middle-aged adults.