Age-related trends (1986-1993) in the use of thrombolytic agents in patients with acute myocardial infarction. The Worcester Heart Attack Study

Abstract

Objective: To examine age-related differences and temporal trends in the use of thrombolytic therapy in a community-wide study of patients hospitalized with acute myocardial infarction (AMI) between 1986 and 1993.

Methods: All hospitals in the Worcester, Mass, metropolitan area (1990 census population, 4370000) were included. A total of 3824 patients with validated AMI categorized according to age comprised the study sample: younger than 55 years (n = 577), 55 to 64 years (n = 758), 65 to 74 years (n = 1143), and 75 years or older (n = 1346).

Results: Use of thrombolytic therapy increased during the period under study in all patients hospitalized with AMI (9% in 1986; 26% in 1993). In 1986, the majority of treated patients received streptokinase; while increases over time in the use of tissue-type plasminogen activator were noted, streptokinase remained the thrombolytic agent of choice in 1993. Marked age-related trends in the use of thrombolytic therapy were observed, with the most striking increases in the use of thrombolytic therapy over time seen in those aged 65 years or older. Between 1986 and 1993 the relative increases in the use of thrombolytic therapy were observed in the following age groups: younger than 55 years (106%), 55 to 64 years (85%), 65 to 74 years (694%), and 75 years or older (571%). Despite these encouraging trends in the use of thrombolytic therapy in older patients, after controlling for a variety of potential confounding variables elderly patients were significantly less likely to receive thrombolytic therapy during hospitalization for AMI. Compared with patients aged 75 years or older, patients younger than 55 years were 6.4 times (95% confidence interval [CI], 4.8-8.5), patients aged 55 to 64 years were 4.9 times (95% CI, 3.8-6.4), and patients aged 65 to 74 years were 3.0 times (95% CI, 2.3-3.9) significantly more likely to receive thrombolytic therapy. These differences were in part related to the proportion of patients with myocardial infarction satisfying eligibility criteria for the receipt of thrombolytic therapy; patients aged 75 years or older were significantly less likely to meet these criteria (19%) than were those younger than 55 years (49%), those aged 55 to 64 years (38%), and those aged 65 to 74 years (28%).

Conclusions: The present results show that while there have been substantial increases over time in the use of thrombolytic therapy in patients with AMI, most particularly in older individuals, the elderly remain appreciably less likely to receive these agents during hospitalization for AMI. These differences may be due to the smaller percentage of elderly patients satisfying criteria for the use of these agents compared with younger patients with coronary heart disease, as well as to a reluctance by physicians to use these agents in older patients. Continued monitoring of these trends remains important for examining changes in physicians' practice patterns regarding the use of thrombolytic therapy in this vulnerable population.