Objective: To determine the effect of the phase of the full and new moon on the variation in the number of daily cardiopulmonary resuscitations.
Design: A retrospective analysis of a computerized billing database of emergency department visits in a cohort of seven northern New Jersey (USA) emergency departments.
Participants: Consecutive patients seen by emergency department physicians over an 11-year period (1 January 1988 to 31 December 1998). We determined the timing of full and new moon days from the National Oceanographic and Aeronautic Administration website.
Interventions: Time series regression estimated the independent effect of full and new moon days on the daily variation in cardiopulmonary resuscitations. Tests of statistical significance were made at α=0.05.
Results: A total of 2 370 233 emergency department visits were made during the 4018-day period of study. A total of 6827 had an emergency department diagnosis of cardiopulmonary resuscitation. We found no significant difference in the occurrence of cardiopulmonary resuscitations during the full moon (P=0.97). On average there were 6.5% fewer cardiopulmonary resuscitations during new moon days (P=0.02; 95% confidence interval 1.3-11.7%).
Conclusion: Contrary to the traditional belief that more cardiopulmonary resuscitations occur during the full moon, we were unable to identify a significant effect during full moon days. However, there were on average 6.5% fewer cardiopulmonary resuscitations during new moon days than other days.