Body mass index and multimorbidity risk: A systematic review and dose-response meta-analysis

Objective: To verify the dose-response relationship between body mass index (BMI) and multimorbidity risk. Methods: PubMed, CINAHL, and Embase were systematically studied until January 25, 2023. Original articles on BMI and multimorbidity risk were included. Random effects model and dose-response meta-analysis were used to estimate the pooled odds ratio (OR) with 95 % confidence interval (CI). Subgroup analysis was performed to explore potential heterogeneity. Results: A total of 43 studies involving 969,130 patients (94,978 with multimorbidity) were involved in the metaanalysis. In the longitudinal studies, the pooled results showed that, compared to being a normal BMI, being overweight was much similar with 1.32 times possibility of getting multimorbidity; in persons with obesity the risk was 1.93 times higher; and the risk decreased 0.80 times among underweight persons. Additionally, obesity was 1.75 times as likely to be multimorbidity than those non-obese persons. In the cross-sectional studies, the pooled results demonstrated that persons with overweight and obesity had a 1.38 -fold and 2.38 -fold risk for multimorbidity, respectively; and the risk decreased 0.90 times among underweight persons compared to those with normal BMI. Besides, obese people are 1.89 times more likely to have multimorbidity than non-obese people. Dose response analysis found the linear connection between BMI and multimorbidity risk ( P non-line- arity =0.762), that for each 1 kg/m 2 and 5 kg/m 2 increase in BMI, the multimorbidity risk increased by 6 % and 35 %, respectively. Conclusions: Multimorbidity increased linearly with an increase in BMI. Clinicians should pay attention to persons with abnormal weight, to help them achieve normal BMI.