The risk of kidney dysfunction in metabolically healthy/unhealthy population with normal weight or overweight/obesity: a systematic review and meta-analysis.

Background: Chronic kidney disease (CKD) is a major global health concern with increasing prevalence and associated complications. Obesity and obesity-related metabolic disorders have been linked to chronic kidney disease (CKD), although the evidence is still inconsistent. To investigate the relationship between different obesity phenotypes and the risk of CKD, we conducted a systematic review and meta-analysis.

Method: We conducted a comprehensive search of databases for all relevant studies up to February 2024, without imposing a specific start date, for observational studies assessing the relationship between obesity phenotypes and incident kidney dysfunction. We used fixed and random effects models for the meta-analysis, subgroup analyses were carried out to explore heterogeneity, and Egger's and Begg's tests were used to assess publication bias.

Result: This meta-analysis included 13 eligible observational studies with 492,829 participants. Pooling the studies regardless of the effect measure showed that individuals with metabolically unhealthy normal weight (MUNW) (ES = 1.58, 95% CI = 1.43-1.76), metabolically healthy obese (MHO) (ES = 1.20, 95% CI = 1.06-1.34), and metabolically unhealthy obese (MUO) (ES = 1.90, 95% CI = 1.63-2.20) phenotypes had a significantly increased risk for kidney dysfunction (KD) events. On the other hand, MUOW individuals did not significantly correlate with risk of CKD (ES = 1.63, 95% CI = 0.97-2.23) compared to the MHNW phenotype.

Conclusion: Healthy overweight and obese individuals had higher risk for the incident KD events; refuting the notion that metabolically healthy overweight and obese phenotypes are benign conditions.

Level of evidence: III Evidence obtained from well-designed cohort or cross-sectional studies.