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.