Prognostic value of routinely available data in patients with stable coronary heart disease. A 10-year follow-up of patients sampled at random times during their disease course

Abstract

Objective: To characterise the long-term prognosis of patients with stable coronary artery heart disease by means of 'standard predictors' defined as demographic, clinical and biochemical quantities routinely available in general practices and ascertained at an interview not prompted by renewed cardiac complaints.

Methods: This is an observational study based on data from 2199 Copenhagen placebo patients from the 'clarithromycin for patients with stable coronary heart disease' trial of patients with stable coronary heart disease. In the trial, we compared the effects of 14 days of clarithromycin treatment versus placebo. The predictors were based on the interview forms and blood samples collected at entry, along with demographic information from hospital files.We studied 'standard predictors' of a composite outcome (myocardial infarction, unstable angina, cerebrovascular disease or all-cause death) and of all-cause death. Using Cox regression, we compared predictions of status at 3, 6 and 9 years without and with the use of 'standard predictors' and used receiver operating characteristic statistic.

Results: Few 'standard predictors' were associated (p<0.01) with the composite outcome or with all-cause death. When no 'standard predictors' were included, 63.2% of the model-based predictions of the composite outcome and 79.9% of death predictions were correct. Including all 'standard predictors' in the model increased the figures to 68.4% and 83.4%, respectively. C indices were low, except when all-cause death was assessed as a single outcome where C was 0.79.

Conclusion: 'Standard predictors' routinely available in general practices contribute only modestly to risk assessment in consecutively sampled patients with stable coronary heart disease as ascertained at a contact not prompted by renewed cardiac complaints. Novel biomarkers may improve the assessment.

Trial registration number: NCT00121550.

Keywords: CLARICOR; cardiovascular disease; ischaemic heart disease; mortality.; predictors.

Figure 1

(A) Kaplan-Meier estimate (with 95% CI) of composite outcome including acute myocardial infarction, unstable angina pectoris, cerebrovascular disease, and all-cause death. Figures below the curve are biannual number at risk in the placebo group of the CLARICOR trial. (B) Kaplan-Meier estimate (with 95% CI) of the outcome all-cause death. Figures below the curve are biannual number at risk in the placebo group of the CLARICOR trial.

Figure 2

(A) ROC diagram (death vs survival at 9 year data). (B) Predicted imapct curves. ROC, receiver operating characteristic.