Statistical Analysis
PSA failure, Deaths
REGRESSION, EVENTS, DISEASE, SECONDARY
The baseline characteristics of the study cohort at the time of randomization were presented using descriptive statistics in a tabular format. The primary end point was time to PSA failure, defined as time from randomization to earliest date of PSA nadir plus 2 ng/mL or the initiation of salvage therapies, such as ADT, brachytherapy, or radical prostatectomy, or censored at the date of last disease assessment for those alive and without PSA failure. Deaths from non-PC causes were counted as competing risk events.In this secondary analysis of a randomized clinical trial, the intent of the study was to assess the prognostic association between baseline clinical factors and time to PSA failure. Clinical factors evaluated included age (categorically defined as younger than 60 years vs 60 to 69 years vs 70 years or older), PSA (categorically defined as less than 4 ng/mL vs 4 to less than 10 ng/mL vs 10 to 20 ng/mL vs more than 20 ng/mL), biopsy Gleason score (categorically defined as 8 to 10 vs 7 vs 6 or less), clinical T-category (categorically defined as T3-4 vs T2 vs T1), ECOG performance status (categorically defined as 1 vs 0) and use of pelvic RT. To fulfill this objective, for each baseline factor of interest, graphical cumulative incidence rate (CIR) curves of PSA failure were produced, treating non-PC deaths as competing events. A Gray test was used to compare these curves for each baseline clinical factor of interest. Meanwhile, the CIR estimates of PSA failure at 3 and 5 years were provided with 95% CIs. Furthermore, to more quantitatively evaluate the association of baseline clinical factors of interest with PSA failure, a multivariable competing risk regression for the subdistribution hazard ratio (sHR) using the Fine and Gray model was applied. The model is stratified by regions (US-Northeast, US-West, US-other, Australia, and New Zealand), and randomization arm. Statistical significance was defined as 