Stage-dependent associations between bariatric surgery and chronic kidney disease outcomes in an inpatient database study

Bariatric surgery improves obesity-related metabolic dysfunction linked to chronic kidney disease (CKD), including diabetes, hypertension, and systemic inflammation. However, whether its association with CKD differs across disease stages and cardiometabolic risk profiles remains unclear. We examined stage-specific associations between bariatric surgery and CKD in a nationally representative cohort.

We conducted a cross-sectional analysis using the 2022 Healthcare Cost and Utilization Project Nationwide Inpatient Sample. Adult hospitalizations were categorized by history of bariatric surgery. CKD outcomes included no CKD, stage 3, stages 4-5, and end-stage renal disease (ESRD). Multivariable logistic regression estimated adjusted odds ratios (aORs). Effect modification was assessed using interaction and stratified analyses. Sensitivity analyses included covariate exclusion, inverse probability of treatment weighting (IPTW), and propensity score matching (PSM).

Among 6,578,372 hospitalizations, 66,776 (1.0%) had a history of bariatric surgery. After adjustment, bariatric surgery was associated with lower odds of any CKD (aOR 0.92, 95% CI 0.87-0.98) and stages 4-5 CKD (aOR 0.74, 95% CI 0.63-0.86), but not stage 3 CKD (aOR 1.02, 95% CI 0.95-1.10) or ESRD (aOR 0.92, 95% CI 0.81-1.04). The association with advanced CKD was more pronounced among patients with obesity (aOR 0.70) and diabetes (aOR 0.69), whereas no significant association was observed among patients without these conditions; the association was also stronger in females than in males. Estimates were directionally consistent across sensitivity analyses, although effect sizes varied (IPTW OR 0.87; PSM OR 0.56).

Bariatric surgery was associated with lower odds of advanced CKD, with associations concentrated in metabolically high-risk populations. These findings suggest that the relationship between bariatric surgery and CKD differs by disease stage and may be most evident in more advanced disease, rather than early-stage CKD or ESRD.