Seasonal and weekly patterns of hospital admissions for nonfatal and fatal myocardial infarction

Objective: This retrospective study, based oil the database of hospital admissions of the region Emilia-Romagna [RER], Italy, was aimed to confirm the existence of a seasonal or weekly pattern of hospital admission of acute myocardial infarction (AMI) and to verify possible differences between nonfatal or fatal cases. Methods: The study included all cases of patients with AMI hospitalized between 1998 and 2006. Day of admission was categorized, respectively, into four 3-month intervals, into twelve 1-month intervals, and into seven I-day intervals for statistical analysis, performed by chi(2) test goodness of fit and partial Fourier series on total cases, males, females, and nonfatal and fatal cases. Results: The database included 64 191 cases of AMI (62.9% males, 12.3% fatal). Acute myocardial infarction was most frequent in winter and least in summer (P<.0001). The highest number of cases was recorded in January and the lowest in July (P <.0001). Chronobiologic analysis showed winter peaks for total cases (January, P =.035), females (December, P =.009), and fatal cases (January, P <.001). Acute Myocardial infarction was most frequent on Monday and least oil Sunday (P <.0001). Comparing observed vs expected events, there was a significantly higher frequency of cases oil weekdays and reduced on weekend,, for total (P <.0001), nonfatal (P <.0001), and fatal cases (P =.0001). Conclusions: This study confirms a significantly higher frequency of AMI admissions in winter and on a Monday. No difference in the frequency of nonfatal vs fatal events, depending of patients' admissions on weekdays or weekends, was found. (C) 2009 Elsevier Inc. All rights reserved.