The Detrimental Effect of Metabolic Syndrome on Long-term Renal Function in Patients Undergoing Elective Partial Nephrectomy for Small Renal Masses

Background and objective: Metabolic syndrome (MetS) is a clinical condition associated with higher rates of overall and cardiovascular mortality. There is scarce evidence regarding the impact of MetS on surgical and functional outcomes for patients undergoing partial nephrectomy (PN) for clinically localized small renal masses (SRMs).

Methods: We analyzed data from a prospectively maintained institutional database for 690 patients with cT1a renal cancer undergoing PN between 2000 and 2023 at a tertiary referral center. MetS was defined according to international guidelines. Cumulative incidence curves were used to estimate the 5-yr risk of stage IIIB-V chronic kidney disease (CKD) stage and other-cause mortality (OCM). Multivariable regression models were used to analyze the impact of MetS on the risk of complications, acute kidney injury (AKI), stage IIIB-V CKD, and OCM.

Key findings and limitations: Overall, 10% of the PN cohort had MetS. The MetS group was older (median age 70 yr, interquartile range [IQR] 65-74 vs 61 yr, IQR 50-69; p < 0.001) and had worse preoperative kidney function (median estimated glomerular filtration rate 65 [IQR 62-81] vs 88 [IQR 69-98] ml/min/1.73 m²; p < 0.001) than the group without MetS. The MetS group had higher incidence of complications (odds ratio [OR] 1.81, 95% confidence interval [CI] 1.05-3.08; p = 0.03) and postoperative AKI (OR 3.17, 95% CI 1.54-6.41; p = 0.001). The 5-yr risk of stage IIIB-V CKD (45% vs 7.2%; hazard ratio [HR] 2.34, 95% CI 1.27-4.30; p = 0.006) and OCM (14% vs 3.5%; HR 3.00, 95% CI 1.06-8.55; p = 0.039) were also higher in the MetS group. The main limitations are the extended accrual time and unmeasured confounders that could potentially affect outcomes.

Conclusions and clinical implications: Patients with MetS had worse postoperative, functional, and survival outcomes after SRM surgery in comparison to patients without MetS. Multidisciplinary care could help in reducing the preoperative metabolic burden in these patients. Further research should explore if alternative approaches (eg, surveillance or focal therapy) could minimize postoperative comorbidities and protect long-term renal function in this population.

Patient summary: Patients with a condition called metabolic syndrome who have part of their kidney removed for small kidney tumors are at higher risk of complications and long-term kidney issues. Patient care from a multidisciplinary team could help in reducing the metabolic burden before surgery. Further research is needed to explore if less invasive treatment options could reduce these risks.