Age-related differences in in-hospital mortality and the use of thrombolytic therapy for acute myocardial infarction

Background: Recent guidelines have acknowledged that thrombolysis decreases mortality from acute myocardial infarction (AMI) independently of age. The purpose of this study was to determine the age-related rates of thrombolyt ic administration and in-hospital mortality and the variables related to th e use of thrombolytic therapy for patients with AMI. Methods: A prospective cohort analysis involved a registry of 44 acute care Quebec hospitals that enrolled 3741 patients with AMI between January 1995 and May 1996. The main outcomes of interest were crude and adjusted age-re lated in-hospital mortality rates and rates of use of thrombolytic therapy. Results: In-hospital mortality rates increased dramatically with age from 2 .1% in patients with AMI who were less than 55 years of age to 26.3% in tho se who were 85 years of age or older. Overall, 35.8% of the patients receiv ed thrombolysis. There was a pronounced inverse gradient in the use of thro mbolysis with age, ranging from 46.2% in the youngest age group (< 55 years ) to 9.5% in the oldest group (<greater than or equal to> 85 years). After adjustment for potential confounders, the older patients remained significa ntly less likely to receive thrombolytic therapy. Compared with patients wh o were less than 55 years of age, the odds ratio of receiving thrombolytic therapy was 0.68 (95% confidence interval [CI] 0.52-0.89) for patients aged 65-74 years, 0.48 (95% CI 0.35-0.65) for patients aged 75-84 years and 0.1 3 (95% CI 0.06-0.26) for patients aged 85 years or more. Other variables re lated to thrombolytic therapy were diabetes (odds ratio [OR] 0.77, 95% CI 0 .59-1.00), cerebrovascular disease (OR 0.46, 95% CI 0.30-0.72), angina (OR 0.73, 95% CI 0.56-0.95), typical chest pain (OR 2.56, 95% CI 1.88-3.47), ST elevation (OR 8.93, 95% CI 7.24-11.00), Q wave MI (OR 5.26, 95% CI 4.20-6. 60) and increased length of time between onset of symptoms and arrival at h ospital. Interpretation: Age is an important independent predictor of in-hospital mo rtality and lower thrombolytic use following AMI. Other studies are require d to further evaluate the appropriateness of thrombolytic therapy for elder ly patients.