Respective contribution of conventional risk factors and antihypertensive treatment to stable angina pectoris and acute coronary syndrome as the first presentation of coronary heart disease: the PRIME Study

OBJECTIVE: To test whether conventional risk factors and antihypertensive treatment were more predictive of stable angina (SA) than acute coronary syndrome (ACS) as the first presentation of coronary heart disease (CHD). DESIGN: We used data from the PRIME Study (Prospective Epidemiological Study of Myocardial Infarction), a prospective cohort of 9758 asymptomatic middle-aged men recruited from WHO MONICA centers in Northern Ireland and France between 1991 and 1993. SA and ACS events were registered during 5 years of follow-up. METHODS: Hazard ratios (HRs) of each risk factor measured at baseline for SA and ACS events were assessed using separate Cox proportional hazard models. Difference between HRs was estimated by the bootstrap method. RESULTS: After 5 years of follow-up, there were 114 SA and 178 ACS as the first presentation of CHD. Diastolic blood pressure [adjusted HRs for 1 standard deviation increase = 1.34; 95% confidence interval (CI): 1.17-1.54 vs. 1.04; 95% CI: 0.87-1.25; P for comparison between HRs = 0.012], and possibly cigarette smoking over or equal to 20 pack-years (adjusted HR = 2.07; 95% CI: 1.43-2.99 vs. 1.29; 95% CI: 0.83-2.01; P for comparison between HRs = 0.062) were more predictive of ACS than SA, whereas this was the opposite for antihypertensive treatment (adjusted HR = 2.18; 95% CI: 1.39-3.41 for SA vs. 1.28; 95% CI: 0.85-1.93 for ACS, P for comparison between HRs = 0.049). CONCLUSION: The present data support that SA and ACS, as the first presentation of CHD, may not share exactly the same determinants.