Association of body mass index with risk of cardiometabolic disease, multimorbidity and mortality: a multi-state analysis based on the Kailuan cohort

Purpose To evaluate the association of body mass index (BMI) with risk of first cardiometabolic disease (FCMD), cardiometabolic multimorbidity (CMM) and death. Methods 87,512 participants free of CMD were included from the Kailuan cohort, which was established during 2006–2007 and followed up until 2020. BMI was classified as underweight ( < 18.5 kg/m 2 ), healthy weight (18.5–23.9 kg/m 2 ), overweight (24.0–27.9 kg/m 2 ), mildly obese (28.0–31.9 kg/m 2 ), and severely obese ( ≥ 32.0 kg/m 2 ). FCMD was defined as the first onset of diabetes, heart disease, or stroke, and CMM as the coexistence of at least two CMD. The hazard ratio (HR) and 95% confidence interval (95%CI) were estimated with multi-state models. Results 20,577 participants developed FCMD, 2232 developed CMM afterwards, and 10,191 died. Individuals with higher BMI was more likely to develop FCMD and CMM. Compared with healthy weight, the HR (95%CI) of severe obesity for transition from health to FCMD and from FCMD to CMM was 3.12 (2.91, 3.34) and 1.92 (1.60, 2.31), respectively. On the other hand, underweight was consistently associated with higher mortality risk regardless of initial status, whereas severe obesity was only related to increased risk for transition from health to death (HR: 1.36; 95%CI: 1.17, 1.56) but not for transition from FCMD (HR: 0.70; 95%CI: 0.57, 0.87) or CMM (HR: 0.80; 95%CI: 0.54, 1.19) to death. Conclusion Our findings highlighted the importance of maintaining healthy weight for primary and secondary prevention of CMD and reflected the demand for more accurate measurement and comprehensive management of obesity for CMD patients.