BACKGROUND: There are conflicting data regarding the relationship between the number of modifiable traditional risk factors and prognosis in acute coronary syndromes (ACS). This controversy might in part be explained by the differential use of prehospital medications.
METHODS: Using data from the Canadian, multicentre Global Registry of Acute Coronary Events (GRACE) (1999-2008), we stratified 13,686 ACS patients into 3 groups (0, 1-2, vs 3-4 risk factors) and compared their baseline characteristics, in-hospital treatments, and outcomes. Multivariable logistic regressions were performed to adjust for the components of the GRACE risk score and preadmission statin and acetylsalicylic acid (ASA) use.
RESULTS: Among these patients (ST-elevation myocardial infarction 28.3%), 14.5%, 62.6%, and 22.9% had 0, 1-2, and 3-4 risk factors, respectively. Patients with fewer risk factors were less likely to be on ASA, statin, and other prehospital medications. Unadjusted in-hospital mortality was significantly different across risk factor groups (4.9%, 3.0%, and 3.1% for 0, 1-2, and 3-4 risk factor groups, respectively, P for trend = 0.002). This difference was no longer significant after adjusting for the components of the GRACE risk score (P for trend = 0.088) and further adjusting for preadmission statin and ASA use (P for trend = 0.96). For in-hospital mortality, there was no significant interaction between risk factor categories and ACS type (P = 0.26).
CONCLUSIONS: The lower mortality observed in patients with ACS with more risk factors may be partially attributed to the protective effect of prehospital ASA and statin use. The number of risk factors does not provide incremental prognostic value beyond the validated GRACE risk score.