Calendar patterns in the occurrence of cardiac arrest

Our objective was to determine whether monthly and daily patterns existed in cardiac arrests in a 7 emergency department (ED) cohorts in New Jersey. We conducted a retrospective analysis of a computerized database over an 11-year period containing 2,370,233 patient visits and 6,827 nontraumatic cardiac arrests. Time-series regression revealed colder months having more cardiac arrests, especially for patients >or=65 years of age. In that age group, December and March were highest with 17% more (P =.002) than the average of nonsignificant months. August was the lowest with 19% (P =.001) fewer cardiac arrests. Day-of-week variation was found only for patients <65 years of age. Saturdays and Mondays had more arrests than nonsignificant days, 15% (P <.0001) and 9% (P =.01), respectively. We conclude that there are monthly and daily patterns in cardiac arrests, with more arrests in the colder months for those >or=65 years of age, and more for ages <65 on Saturdays and Mondays.