Overweight, obesity and risk of multimorbidity: A systematic review and meta-analysis of longitudinal studies

This study aimed to review and quantify the association between overweight and obesity in the risk of multimorbidity among the general population. We conducted a systematic review and meta-analysis in the databases of Pubmed, Lilacs, Web of Science, Scopus, and Embase. We included cohort studies that assessed the association between overweight and/or obesity with the risk of multimorbidity. The Newcastle-Ottawa assessed the studies' individual quality. A random-effect model meta-analysis was performed to evaluate the association between overweight and obesity with the relative risk (RR) of multimorbidity; the I² test evaluated heterogeneity. After excluding duplicates, we found 1.655 manuscripts, of which eight met the inclusion criteria. Of these, seven (87.5%) evidenced an increased risk of multimorbidity among subjects with overweight and/or obesity. Overall, we observed an increased risk of multimorbidity among subjects with overweight (RR: 1.26; CI95%: 1.12; 1.40, I²  = 98%) and obesity (RR: 1.99; CI95%: 1.45;2.72, I²  = 99%) compared to normal weight. According to the I² test, the heterogeneities of the meta-analyses were high. The Newcastle-Ottawa scale showed that all studies were classified as high quality. Further longitudinal studies are needed, including different populations and stratifications by sex, age, and other variables.