Time trends in prognosis of patients with myocardial infarction: a population-based study.

A population-based study was conducted in metropolitan Baltimore, in which the prognosis of 504 patients hospitalized with acute myocardial infarction (MI) from July 1966 through June 1967 was compared with that of 803 patients hospitalized from January through December 1971. For patients admitted to coronary care units (CCUs), the in-hospital case-fatality rate (CFR) in 1971 (20%) was found to be significantly lower than that in 1966/67 (27.5%) (p less than .025), after simultaneous adjustment for 16 variables which may affect prognosis. No such significant difference was detected for patients not admitted to CCUs when the two time periods were compared. As a result of these time trends, CFRs were not significantly different between CCU and non-CCU patients in 1966/67, but in 1971 a significant advantage was shown for CCU patients (p less than .005). These results suggest that effectiveness of CCUs in prevention of in-hospital deaths increased between 1966/67 and 1971. For hospital survivors, regardless of admission to a CCU, no significant differences in long-term prognosis were found between patients discharged in 1971 and those discharged in 1966/67. This finding may reflect the lack of major therapeutic advances between the two study periods, aimed at reducing the progression of coronary atherosclerosis and/or the extent of the infarcted area.