External validation of a simplified prognostic model for survival in patients with extrinsic malignant ureteral obstruction treated with tandem ureteral stents – a retrospective cohort study

Abstract

Introduction Prognostic models of survival can identify patients with extrinsic malignant ureteral obstruction who will benefit from long-term drainage as offered by tandem ureteral stents. The study aims to validate a simplified prognostic model published by Cordeiro et al. and to identify additional prognostic predictors in a cohort of patients drained solely with tandem ureteral stents. Methods Medical records of consecutive patients who underwent drainage of malignant ureteral obstruction with tandem ureteral stents between 2007 and 2020 were reviewed retrospectively; patients with benign ureteral obstruction were excluded. Risk factors for survival included were: [1] the number of malignancy-related events (categorized as ≥4 and <4) and [2] the Eastern Cooperative Oncology Group Index (categorized as ≥2 and <2)]. Patients with ≥1 risk factor were grouped as intermediate-unfavorable risk and those without risk factors as favorable risk. The Kaplan–Meier and log-rank tests were used for survival analysis. Univariable and multivariable Cox regression analyses were used to identify predictors of outcome. Results The study cohort consisted of 65 patients; the median age was 60 years (IQR 51–72). The median follow-up time from diagnosis of hydronephrosis was 51 months (IQR 38–64). Estimated probabilities of survival at 1 month, 6 months 1 year, and 2 years were 100%, 87%, 75% and 57%, respectively in the favorable risk group (n = 40), and in the intermediate-unfavorable risk group (n = 25), 96%, 72%, 52%, and 20%, respectively, (p = .003). On multivariable analysis, the presence of ≥4 malignancy-related events (HR = 2.04, 95% CI [1.07–3.86], p = .03) and lung metastasis (HR = 2.37, 95% CI [1.0–5.6], p = .05) were associated with shorter survival. Conclusions Our findings validate the prognostic model published by Cordeiro et al. The model can be applied when counseling patients being considered for drainage with tandem ureteral stents.