Statistical Analysis
REGRESSIONS
Data were analyzed from January 13, 2022, to March 10, 2023. Mean resource use was estimated and compared using unpaired, 2-tailed Missing data for EQ-5D-5L utility score (at baseline, 5 days, 5 weeks, and 12 weeks) were based on 20 imputed data sets. The imputed data sets were established in chain regressions with covariates of age, sex, and group. All analyses, unless otherwise stated, were undertaken in Stata, version 17 (StataCorp LLC).Incremental cost-effectiveness ratios (ICERs) were calculated using the coefficients of the treatment variables of the seemingly unrelated regressions. Five thousand mean values for incremental costs and QALYs were bootstrapped and plotted on the cost-effectiveness plane to give a cost-effectiveness acceptability curve. The main conclusions of the analysis are based on a United Kingdom funding threshold of £20 000 (US $28 8960) per QALY gained.Preplanned subgroup analyses included the following: chemotherapy vs no chemotherapy, stage T2 or less vs T3 or greater, age younger than 70 years vs 70 years or older, performance status 0 vs 1 or greater on the ECOG Performance Status Scale (score range, 0 [fully active] to 5 [dead]), male vs female sex, and type of diversion, consisting of ileal conduit vs neobladder or other reconstruction. A further post hoc analysis was undertaken to assess where body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) may be a potential effect modifier.Sources of methodological and cost uncertainty were identified and explored through deterministic sensitivity analyses. Sources relating to methodological uncertainty included:complete case analysis (cases with complete EQ-5D-5L data at baseline and 5 weeks and 90 days post surgery);omission of the day 5 utility imputation;use of last observation carried forward for missing data;scoring the EQ-5D-5L using an alternative algorithmextrapolation of day 90 results assuming convergence of mean utilities at 180, 270, and 360 days post surgery.lower theater cost per minute for iRARC;lower ORC equipment costs;lower cost of a day on a ward;alternative life span and throughput of the surgical robot; andalternative hospital costs.