Prognostic value of the CAPRA clinical prediction rule: a systematic review and meta-analysis

WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: Prostate cancer is a significant cause of mortality among men. A number of prognostic instruments exist to predict the risk of recurrence among patients with localised prostate cancer. This systematic review examines the totality of evidence in relation to the predictive value of the CAPRA clinical predication rule by combining all studies that validate the rule.

To perform a systematic review with meta-analysis that assesses the 3- and 5-year predictive value of the CAPRA rule, a clinical prediction rule derived to predict biochemical-recurrence-free survival in men with localized prostate cancer after radical prostatectomy. To examine the predictive value of the CAPRA rule at 3 and 5 years stratified by risk group (0-2 low risk, 3-5 intermediate risk, 6-10 high risk).

A systematic literature search was performed to retrieve papers that validated the CAPRA score. The original derivation study was used as a predictive model and applied to all validation studies with observed and predicted biochemical-recurrence-free survival at 3 and 5 years stratified by risk group (0-2 low, 3-5 intermediate, 6-10 high). Pooled results are presented as risk ratios (RRs) with 95% confidence intervals, in terms of over-prediction (RR > 1) or under-prediction (RR < 1) of biochemical-recurrence-free survival at 3 and 5 years. A chi-squared test for trend was computed to determine if there was a decreasing trend in survival across the three CAPRA risk categories.

Seven validation studies (n = 12 693) predict recurrence-free survival at 5 years after radical prostatectomy. The CAPRA score significantly under-predicts recurrence-free survival across all three risk strata (low risk, RR 0.94, 95% CI 0.90-0.98; intermediate risk, RR 0.94, 95% CI 0.89-0.99; high risk, RR 0.72, 95% CI 0.60-0.85). Data on six studies (n = 6082) are pooled to predict 3-year recurrence-free survival. The CAPRA score correctly predicts recurrence-free survival in all three groups (low risk, RR 0.98, 95% CI 0.95-1.00; intermediate risk, RR 1.03, 95% CI 0.99-1.08; high risk, RR 0.87, 95% CI 0.73-1.05). The chi-squared trend analysis indicates that, as the trichotomized CAPRA score increases, the probability of survival decreases (P < 0.001).

The results of this pooled analysis confirm the ability of the CAPRA rule to correctly predict biochemical-recurrence-free survival at 3 years after radical prostatectomy. The rule under-predicts recurrence-free survival 5 years after radical prostatectomy across all three strata of risk.