AGE-RELATED TRENDS (1986-1993) IN THE USE OF THROMBOLYTIC AGENTS IN PATIENTS WITH ACUTE MYOCARDIAL-INFARCTION - THE WORCESTER HEART-ATTACK STUDY

Objective: To examine age-related differences and temporal trends in t he use of thrombolytic therapy in a community-wide study of patients h ospitalized with acute myocardial infarction (AMI) between 1986 and 19 93. Methods: All hospitals in the Worcester, Mass, metropolitan area ( 1990 census population, 437 000) were included. A total of 3824 patien ts 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 thr ombolytic therapy increased during the period under study in all patie nts hospitalized with AMI (9% in 1986; 26% in 1993). In 1986, the majo rity of treated patients received streptokinase; while increases over time in the use of tissue-type plasminogen activator were noted, strep tokinase 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 t ime seen in those aged 65 years or older. Between 1986 and 1993 the re lative increases in the use of thrombolytic therapy were observed in t he 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 th ese encouraging trends in the use of thrombolytic therapy in older pat ients, after controlling for a variety of potential confounding variab les elderly patients were significantly less likely to receive thrombo lytic therapy during hospitalization for AMI. Compared with patients a ged 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 we re 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 throm bolytic therapy. These differences were in part related to the proport ion of patients with myocardial infarction satisfying eligibility crit eria for the receipt of thrombolytic therapy; patients aged 75 years o r older were significantly less likely to meet these criteria (19%) th an 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 re sults show that while there have been substantial increases over time in the use of thrombolytic therapy in patients with AMI, most particul arly in older individuals, the elderly remain appreciably less likely to receive these agents during hospitalization for AMI. These differen ces may be due to the smaller percentage of elderly patients satisfyin g 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 t rends remains important for examining changes in physicians' practice patterns regarding the use of thrombolytic therapy in this vulnerable population.