The role of psoas muscle index in predicting outcomes after radical cystectomy

Sarcopenia, defined as a loss of skeletal muscle mass and strength, has been associated with adverse surgical and oncologic outcomes in various malignancies. This study aimed to evaluate whether the psoas muscle area and psoas muscle index (PMI), derived from the preoperative computed tomography imaging, could predict postoperative complications and long-term oncological outcomes in patients undergoing radical cystectomy (RC) for bladder cancer.

We retrospectively analyzed 197 patients who underwent RC between 2014 and 2024. Sarcopenia was defined using sex-specific PMI thresholds based on the lowest quartile for the study population (<7.11 cm²/m² for men and <8.85 cm²/m² for women). Postoperative complications and oncologic outcomes, including overall survival (OS), recurrence-free survival (RFS), and disease-specific mortality (DSM), were assessed using logistic regression and Cox models.

Sarcopenia was present in 24% of the patients. While the 90-day urinary tract infection and readmissions appeared more frequent in sarcopenic women on the univariate analysis, only the readmission rate remained significant after adjustment. Among the men, although the association between sarcopenia and 30-day complications did not reach statistical significance (odds ratio: 2.10, P = 0.075), the effect size suggested a potential trend toward increased risk. Sarcopenia was not an independent predictor of other 30- or 90-day complications, nor of OS, RFS, or DSM. The median follow-up was 30 months (range: 0-129).

In this cohort, PMI-based sarcopenia did not independently predict perioperative complications or long-term oncologic outcomes after RC. These findings suggest that PMI alone may not be a robust indicator of surgical risk or oncologic prognosis in bladder cancer.