Validation of the prostate cancer comorbidity index in predicting cause-specific mortality in men undergoing radical prostatectomy

Purpose: Accurate prediction of competing risks of mortality remains a key component of prostate cancer treatment decision-making. We sought to validate the Prostate Cancer Comorbidity Index (PCCI) score for predicting other-cause mortality (OCM) and cancer outcomes in men undergoing radical prostatectomy (RP). Materials and methods: We sampled 4857 men with prostate cancer treated with RP in the VA from 2000–2018. Risks of OCM, 90-day all-cause mortality (ACM), prostate cancer-specific mortality, metastasis, and biochemical recurrence by PCCI score were assessed using Cox proportional hazards and logistic regression. We compared prediction of 90-day ACM between PCCI and the American Society of Anesthesiology (ASA) score, a validated predictor of short-term mortality. Results: Over median follow-up of 6.7 years (IQR 3.7–10.3), there was a stepwise increase in risk of OCM with higher PCCI score, with hazards (95%CI) of 1.53 (1.14–2.04), 2.11 (1.55–2.88), 2.36 (1.68–3.31), 3.61 (2.61–4.98), and 4.99 (3.58–6.96) for PCCI 1-2, 3-4, 5-6, 7-9, and 10 + (vs. 0), respectively. Projected 10-year cumulative incidence of OCM was 8%, 12%, 16%, 19%, 26%, and 32% for scores of 0, 1-2, 3-4, 5-6, 7-9, and 10+ , respectively. Men with PCCI 7+ had greater odds of 90-day ACM (OR 3.48, 95%CI 1.26–9.63) while men with higher ASA did not. Higher PCCI score was associated with worse cancer outcomes, with the highest categories driving the associations. Conclusions: The PCCI is a robust measure of short- and long-term OCM after RP, validated for use in clinical care and health services research focusing on surgical patient populations.