Long-term Mortality after Acute Myocardial Infarction in Relation to Prescribed Dosages of a Beta-Blocker at Hospital Discharge

Abstract

This study was designed to describe the 5-year mortality rate in relation to the dose of metoprolol prescribed at hospital discharge after hospitalisation for acute myocardial infarction (AMI). All patients discharged alive after being hospitalized for AMI at Sahlgrenska Hospital (covering half of the community of Göteborg, with 500,000 inhabitants) during 1986–1987 (period I) and all patients discharged alive after hospitalization for AMI at Sahlgrenska Hospital and östra Hospital (covering the whole area of the community of Göteborg) in 1990–1991 (period II) were included. Overall mortality was retrospectively evaluated over 5 years of follow-up. In all there were 2161 patients who were discharged after AMI. Seventy-three percent of these patients were prescribed a beta-blocker and 59% were prescribed metoprolol. Of the patients prescribed metoprolol, 34% were on 200 mg, 46% on 100 mg, and 20% on 50 mg or less. Information on 5-year mortality was available for 2142 of the 2161 patients (99.1%). The 5-year mortality was 24% among patients prescribed 200 mg, 33% among patients prescribed 100 mg, and 43% among patients prescribed 50 mg (P < 0.0001). Patients prescribed another beta-blocker had a 5-year mortality of 39%, and patients prescribed no beta-blocker at all had a 5-year mortality of 61%. When correcting for dissimilarities at baseline, patients who were prescribed ≤100 mg had an adjusted risk ratio for death of 0.79 (95% confidence limit 0.64–0.96; P = 0.021) as compared with patients not prescribed a beta blocker. The corresponding figure for patients prescribed >100 mg was 0.63 (95% confidence limit 0.48–0.84; P = 0.001). Both patients prescribed high and low doses of metoprolol after AMI appeared to benefit from treatment. There was a trend indicating more benefit when larger doses were prescribed.