Seasonal and weekly patterns of hospital admissions for nonfatal and fatal myocardial infarction.
OBJECTIVE
This retrospective study, based on 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 1-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 on Sunday (P < .0001). Comparing observed vs expected events, there was a significantly higher frequency of cases on weekdays and reduced on weekends, 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.
Manfredini
Roberto
R
Department of Clinical and Experimental Medicine, Section Clinica Medica and Vascular Diseases Center, University of Ferrara, 44100 Ferrara, Italy. mfr@unife.it
Manfredini
Fabio
F
Boari
Benedetta
B
Bergami
Elisabetta
E
Mari
Elisa
E
Gamberini
Susanna
S
Salmi
Raffaella
R
Gallerani
Massimo
M
D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D016208:Databases, Factual; D004636:Emergency Service, Hospital; D005260:Female; D017052:Hospital Mortality; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007558:Italy; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis / Q000401:mortality* / Q000628:therapy*; D012189:Retrospective Studies; D012621:Seasons; D017678:Sex Distribution