Prognostic impact of different regional referral practices for interventional investigation and coronary treatment after exercise testing: a population-based 5-year follow-up study

OBJECTIVE: To examine the association among different centres' referral practices for coronary angiography (CAG) after exercise testing, with 1- and 5-year outcomes. DESIGN: Observational population-based cohort study. SETTING: All 10 hospitals and six private practising consultants in Aarhus and Ringkjoebing counties (900 000 inhabitants), Denmark. SUBJECTS: All patients who in 1996 had an abnormal bicycle exercise test (n = 736). MEASUREMENTS: Referral for CAG, coronary intervention, cardiovascular and all-cause mortality, and myocardial infarction (MI). RESULTS: As an immediate consequence of the exercise test, 60.7% of subjects were referred for CAG. Based on the centres' fraction of patients referred for CAG, three categories of centres were defined: low (<33%), intermediate (33-66%) and high (>66%). A low compared with a high referral fraction was associated with a similar 5-year mortality and MI ratio all-cause/cardiovascular mortality rate ratio (RR) = 1.33, 95% confidence interval (CI): 0.45-3.92/RR = 0.62, 95% CI: 0.25-1.57; and MI RR = 0.92, 95% CI: 0.45-1.86]. The same was found for an intermediate compared with a high fraction (all-cause/cardiovascular mortality RR = 0.92, 95% CI: 0.49-1.72/RR = 0.74, 95% CI: 0.42-1.33; and MI RR = 1.07, 95% CI: 0.68-1.70). Estimates were about the same after 1 year of follow-up with no major differences among centres in mortality or MI. CONCLUSIONS: Centres' different referral practices for interventional investigation and treatment were not associated significantly with short-term or long-term mortality or MI among patients with an abnormal exercise test.