External validation of the CACE-HF risk score for mortality in patients with heart failure

Abstract

Aims: To validate externally the CACE-HF clinical prediction rule, which predicts 1-year mortality in patients with heart failure (HF).

Methods: We performed an external validation of the CACE-HF risk score in patients included in the RICA heart failure registry who had completed 1 year of follow-up, comparing the characteristics of the derivation and validation cohorts. The performance of the risk score was evaluated in terms of calibration, using calibration-in-the-large (a), calibration slope (b), and the Hosmer-Lemeshow test, and in terms of discrimination, using the area under the ROC curve.

Results: In total, 3337 patients were included in the validation cohort. There were no significant differences between the derivation and validation cohorts in 1-year mortality (24.63% vs. 22.98%) or in the risk score and risk classes. The discrimination capacity in the validation cohort was slightly lower, 0.67 (95% CI: 0.65, 0.69), compared to that of the derivation cohort. Calibration results were a -0.05 (95% CI: -0.14, 0.03), indicating that the average predictions did not differ from the average outcome frequency, and b = 0.75 (95% CI: 0.64, 0.86), indicating a modest inconsistency in predictor effects. Observed mortality versus predicted mortality according to the deciles and risk classes were very similar in both cases, indicating good calibration.

Conclusions: The results of the external validation of the CACE-HF risk score show that although the capacity for discrimination was slightly lower than in the derivation cohort, the calibration was excellent. This tool, therefore, can assist in decision-making in the management of these patients.

Keywords: Clinical prediction rule; Heart failure.