Preoperative muscle quantity to predict acute kidney injury after radical cystectomy: A multicenter retrospective study.

723 Background: Acute kidney injury (AKI) is a common complication in patients undergoing radical cystectomy (RC), yet its risk factors remain poorly defined. AKI is diagnosed based on elevations in serum creatinine levels, which are primarily influenced by skeletal muscle mass—the main source of creatinine production. Therefore, we hypothesized that preoperative muscle quantity and quality may play a critical role in the development of AKI following RC. Methods: This multicenter retrospective cohort study included 918 patients with bladder cancer who underwent RC. AKI was defined according to the KDIGO criteria. Muscle quantity and quality were assessed using the psoas index (PI) and intramuscular adipose tissue content (IMAC), respectively, based on computed tomography images obtained within one month prior to RC. Optimal cutoff values for predicting AKI were determined separately for men and women using receiver operating characteristic curve analysis. A higher PI and lower IMAC reflect greater muscle quantity and quality, respectively. Multivariable logistic regression analyses were conducted to evaluate the association between muscle metrics and AKI risk. Results: The median age was 70 years. Of the 918 patients, 479 (52%) developed AKI of any stage. Among them, 540 (59%) had higher PI values and 641 (70%) had lower IMAC values. IMAC values were not significantly correlated with PI values (ρ = 0.021, P = 0.530). The incidence of AKI was significantly higher in patients with higher PI values (indicative of greater muscle quantity) than in those with lower PI values (56% vs. 47%, P = 0.007). Conversely, patients with lower IMAC values (indicative of better muscle quality) had a significantly lower incidence of AKI compared to those with higher IMAC values (50% vs. 57%, P = 0.037). After adjustment for confounding variables, higher muscle quantity (higher PI values) was significantly associated with AKI development ( P = 0.003; odds ratio [OR]: 1.590; 95% confidence interval [CI]: 1.166–2.168), whereas muscle quality (lower IMAC values) was not ( P = 0.904; OR: 0.979; 95% CI: 0.698–1.375). Conclusions: Patients with greater muscle quantity were at increased risk of AKI following RC. In contrast, muscle quality did not significantly influence AKI development. Multivariable analysis for AKI development. Factor P value Odds ratio 95% CI Age Continuous 0.124 1.014 0.996–1.033 Sex Male 0.002 1.747 1.236–2.470 Performance status Continuous 0.055 1.398 0.992–1.971 Body mass index Continuous 0.055 1.045 0.999–1.093 Hypertension Presence 0.003 1.556 1.158–2.089 Preoperative eGFR Continuous <0.001 0.984 0.976–0.992 Higher muscle quantity Presence 0.003 1.590 1.166–2.168