The higher mortality rate in acute myocardial infarction patients admitted to the hospital on weekends compared with weekdays can be attributed in part to a reduced rate of invasive cardiac procedures on weekends, reported William J. Kostis, Ph.D., of Robert Wood Johnson Medical School, Piscataway, N.J.
Dr. Kostis and his associates used information in the Myocardial Infarction Data Acquisition System (MIDAS) database to determine whether MI-related mortality is higher with weekend presentation, and whether this could be explained by the use of invasive cardiac procedures, length of hospital stay, or patient characteristics.
The database includes the records of more than 231,000 MI patients treated between 1987 and 2002, “virtually all patients admitted to [any] New Jersey hospital over a 16-year period for a first myocardial infarction.”
Thirty-day mortality showed “a significant and clinically relevant” increase among patients admitted on a Saturday or Sunday rather than on a weekday, “representing 9 to 10 additional deaths per 1,000 admissions per year.” This increased mortality persisted for a full year of follow-up, and “could account for several thousand deaths annually in the United States,” the investigators said. “Even small differences in mortality between weekday and weekend admissions of patients with acute MI can translate to substantial numbers of additional deaths in the population because of the high incidence and case fatality rate associated with this condition,” the researchers said (N. Engl. J. Med. 2007;356:1099–109).
Patients who were admitted on weekends were less likely to undergo cardiac catheterization, percutaneous coronary intervention, or coronary artery bypass graft surgery than were those admitted on weekdays, and when they did have such procedures, they were more likely to experience a significant delay of several days compared with people who had weekday admissions. These results persisted after the data were adjusted to account for demographic characteristics, infarction site, presence or absence of concomitant illness, and presence or absence of complications.
The association between timing of admission and mortality was not related to patient characteristics or length of stay. It was due primarily to the difference in use of invasive cardiac procedures. These results persisted when the data analysis was restricted to several subgroups, such as patients treated at percutaneous coronary intervention-equipped hospitals.
“Overall, our study suggests that a hospital workweek of Monday through Friday is not optimal for the care of patients with acute MI,” the authors added.