title: Emergency admissions of opioid drug abusers for overdose: a chronobiological study of enhanced risk.
abstract: OBJECTIVE
  To determine whether there is a specific temporal risk for opioid drug overdose.
  
  
  METHODS
  To study patients presenting to the ED in a comatose state from accidental drug opioid overdose.
  
  
  METHODS
  Two hundred seventy-four patients were admitted to the ED of the Hospital of Ferrara, Italy, from 1988 to 1990, 225 men (82.1%; mean age, 25 +/- 3.4 years) and 49 women (17.9%; mean age, 23.5 +/- 2.8 years).
  
  
  METHODS
  Month, day, and hour and minute of admissions were recorded, and time-qualified frequency data were analyzed by the single cosinor method.
  
  
  RESULTS
  Cosinor analysis demonstrated a significant circadian rhythm for both the total number of observations and the separate male and female subgroups with an early evening peak ("acrophase") at about 7:00 PM. No significant circannual rhythm was evident, but for the total group a significant 6-month rhythm was demonstrable with peaks in late November and late May.
  
  
  CONCLUSIONS
  There is a distinct "chronorisk" of opioid drug overdose in the early evening hours.
authors.affiliation: Institute of Internal Medicine, University of Ferrara, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Manfredini
authors.forename: M
authors.initials: M
authors.lastname: Gallerani
authors.forename: G
authors.initials: G
authors.lastname: Calo
authors.forename: M
authors.initials: M
authors.lastname: Pasin
authors.forename: M
authors.initials: M
authors.lastname: Govoni
authors.forename: C
authors.initials: C
authors.lastname: Fersini
mesh_terms: D000328:Adult; D002909:Chronobiology Phenomena / Q000502:physiology; D002940:Circadian Rhythm; D003128:Coma / Q000139:chemically induced / Q000503:physiopathology; D062787:Drug Overdose; D005260:Female; D006556:Heroin Dependence / Q000503:physiopathology; D006801:Humans; D008297:Male; D009293:Opioid-Related Disorders / Q000503:physiopathology*; D011446:Prospective Studies; D013997:Time Factors