Circadian and circannual rhythms of emergency room drug-overdose admissions.

All Drug Abuse Warning Network (DAWN) records for 1983 from the University of Illinois Emergency Room were collected: a total of 264 drug-overdose (DOD) admissions. Cosinor, multiple linear regression, cross-tab multivariate, and spectral periodicity statistical analyses were performed on the raw data with particular use made of the BMDP statistical package. More DODs present themselves for admission to the ER around the 1820 hr than any other time of the circadian period. Sex, age, and race have no effect on this circadian relationship. No circatrigintan rhythms were found for any sex, race, or age group. However, there is a circannual rhythm for total DOD admissions with more admissions in late July than any other time of the year. Women, however, appear to exhibit a significantly earlier annual acrophase (late May) than males in early August. There is no evidence for circannual, circadiseptan, circaseptan or circabiseptan rhythms for blacks or hispanics. However, whites, particularly males, show evidence of biweekly (i.e., Monday and Friday) as well as circannual rhythms. Multivariate analyses of circannual rhythms vs. age indicated no significant rhythms for the under-21-year-old but a highly significant circannual rhythm for the over-20-year-old. Therefore, ER personnel should be attentive to the sex, age, and race of their patients in order to gain a degree of predictability as to when the greatest number of patients might present themselves at the ER for treatment of their DOD. Awareness of the temporal effects on DOD admissions can thus improve the quality of ER treatment for DOD patients.