Impact of patient characteristics and comorbidities on the risk of postoperative acute kidney injury: a comparative analysis of on clamp vs. off-clamp techniques.

introductionThe role of patient comorbidities in predicting acute kidney injury (AKI) following on-clamp versus off-clamp partial nephrectomy (PN) remains unclear. We investigated how patient characteristics affect the risk of postoperative AKI based on the on-clamp vs. off-clamp surgical technique.

methodsWithin a prospectively maintained database, patients treated with PN for renal cell carcinoma at a tertiary-referral center (2000–2024) were selected. Patients were categorized into two groups based on on-clamp versus off-clamp PN. AKI was defined using the K-DIGO criteria. A multivariable logistic regression model (LRM) assessed the risk of AKI by the presence of ischemia [covariates: age, gender, estimated blood loss, operative time, surgical approach (minimally invasive vs. open), tumor size, preoperative estimated glomerular filtration rate(eGFR)]. Additional separate LRMs evaluated the impact of comorbidities (overweight, age, smoking status, hypertension, gender, diabetes, hypercholesterolemia) on AKI risk according to on and off-clamp technique.

resultsOf 1,048 patients, 802 (77%) underwent on-clamp PN and 246 (23%) underwent off-clamp PN. Patients in the first group had larger median tumor sizes (3.10 cm vs. 2.50 cm, p < 0.001), lower estimated blood loss (200 ml vs. 240 ml, p < 0.001), but longer operative time (160 min vs. 140 min, p < 0.001). Comorbidity distribution was similar between groups, except for hypertension, which was less common in the on-clamp group (49% vs. 59%, p = 0.003). At LRM on-clamp PN was associated with a higher risk of AKI (OR: 2.00, p = 0.003). The effect of being overweight on AKI risk was stronger in the on-clamp group (OR: 1.87, p = 0.001) compared to the off-clamp group (OR: 1.01, p > 0.9). Similarly, age (OR: 1.03, p = 0.038 vs. 1.01, p = 0.7), smoking (OR: 1.58, p = 0.014 vs. 0.98, p > 0.9), hypertension (OR: 1.69, p = 0.010 vs. 1.49, p = 0.4), and male gender (OR: 1.62, p = 0.021 vs. 1.05, p > 0.9) were associated with AKI risk in patients receiving on-clamp PN.

conclusionsIn the on-clamp cohort there was association of BMI, age, active smoking, hypertension and gender with post-operative AKI. These findings underscore the importance of patient selection and preoperative planning, emphasizing the need to include individual patient characteristics when deciding on the surgical approach together with cancer features.