Skeletal Muscle and Fat Mass Indexes Predict Discharge Disposition after Radical Cystectomy.

Abstract

Skeletal muscle and fat mass indexes have emerged as easily obtained, objective and useful tools to assess susceptibility to unfavorable postoperative outcomes. We examined the association between skeletal muscle and fat mass indexes, and the discharge disposition after radical cystectomy. In a retrospectively collected, single institution cohort we studied patients who underwent radical cystectomy with pelvic lymphadenectomy of primary, nonmetastatic muscle invasive bladder cancer between 2009 and 2015. Included patients had undergone adequate axial computerized tomography at the L3 level within 90 days prior to surgery. Skeletal muscle and fat mass indexes were measured on preoperative computerized tomography and relationships to the outcomes of interest were analyzed. Multivariable logistic regression analysis was performed to assess the effect of the skeletal muscle and fat mass indexes on the discharge disposition while controlling for age, comorbidities, complications and previous neoadjuvant chemotherapy. A total of 136 patients met study inclusion criteria. The median skeletal muscle index among women and men in our study cohort was 36.4 and 47.6 cm2/m2, respectively. On multivariable logistic regression analysis a decreased skeletal muscle index (OR 0.94, 95% CI 0.90-0.98) and an increased fat mass index (OR 1.24, 95% CI 1.04-1.48) were associated with greater odds of discharge to a facility. Higher fat mass-to-skeletal muscle [corrected] index ratios were also associated with greater odds of discharge to a facility (OR 1.69, 95% CI 1.22-2.44). Study limitations include the retrospective design and unknown confounders. Low skeletal muscle and high fat compositions are independent predictors of discharge to a facility after radical cystectomy of nonmetastatic muscle invasive bladder cancer.