Background: The aims of this retrospective cohort study are to describe the presentation characteristics for nonfatal overdose-related complaints at the emergency departments (EDs) of the metropolitan area of Bologna (northern Italy), to estimate the subsequent risk of mortality by overdose, and to identify the profiles of the subjects most at risk. Methods: Records of patients admitted to 10 EDs for overdose between January 2004 and December 2012 were retrospectively evaluated. The International Classification of Diseases was used to ascertain the cause of death. Results: A total of 294 episodes of overdose involving 218 individuals were identified. The total time at risk was 1048 person-years (PY). The mortality rate for all causes was 35.48 per 1000 PY for males and 20.61 per 1000 PY for females. The mortality rate for overdose was 16.6 per 1000 PY for males and 13.74 per 1000 PY for females. In the multivariate regression analysis, the time from first ED overdose access (less than 1 year risk ratio [RR]: 7.07, 95% confidence interval [CI]: 5.32–9.39) was significantly associated with death by overdose. Males, subjects aged >30 years at presentation, patients who refused ED treatment, and those having previously contacted mental health services showed an increased mortality risk due to overdose. Conclusions: Experiencing a nonfatal overdose within the past 12 months increases the risk of mortality compared with an overdose more than 12 months earlier. Nonfatal overdose patients presenting to an ED form a specific target for prevention projects.
KerrT, FairbairnN, TyndallM, . Predictors of non-fatal overdose among a cohort of polysubstance-using injection drug users. Drug Alcohol Depend.2007;87:39–45.
4.
SporerKA. Strategies for preventing heroin overdose. BMJ. 2003;326:442–444.
5.
RomeA, ShawA, BoyleK. Reducing Drug Users’ Risk of Overdose. Edinburgh, UK: Scottish Government Social Research; 2008.
6.
BennetGA, HigginsDS. Accidental overdose among injecting drug users in Dorset, UK. Addiction. 1999;94:1179–1189.
7.
O'DriscollPT, McGoughJ, HaganH, . Predictors of accidental fatal drug overdose among a cohort of injection drug users. Am J Public Health. 2001;91:984–987.
8.
CullenW, BuryG, LangtonD. Experience of heroin overdose among drug users attending general practice. Br J Gen Pract.2000;50:546–549.
9.
McGregorC, DarkeS, AliR, . Experience of non-fatal overdose among heroin users in Adelaide, Australia: circumstances and risk perceptions. Addiction. 1998;93:701–711.
10.
BartuA, FreemanNC, GawthorneGS, . Mortality in a cohort of opiate and amphetamine users in Perth, Western Australia. Addiction. 2004;99:53–60.
11.
KerrT., TyndallMW, LaiC, . Drug-related overdoses within a medically supervised safer injection facility. Int J Drug Policy. 2006;17:436–441.
12.
StoovéMA, DietzePM, JolleyD. Overdose deaths following previous non-fatal heroin overdose: record linkage of ambulance attendance and death registry data. Drug Alcohol Rev.2009;28:347–352.
13.
OliverP, KeenJ. Concomitant drugs of misuse and drug using behaviours associated with fatal opiate-related poisonings in Sheffield, UK, 1997–2000. Addiction. 2003;98:191–197.
14.
ZanisDA, WoodyGE. One-year mortality rates following methadone treatment discharge. Drug Alcohol Depend.1998;52:257–260.
15.
DavoliM, PerucciCA, ForastiereF, . Risk factors overdose mortality: a case-control study within a cohort of intravenous drug users, Int J Epidemiol.2003;22:273–277.
16.
DavoliM, BargagliAM, PerucciCA, . Risk of fatal overdose during and after specialist drug treatment: the VEdeTTE study, a national multi-site prospective cohort study. Addiction. 2007;102:1954–1959.
17.
SeamanSR, BrettleRP, GoreSM. Mortality from overdose among injecting drug users recently released from prison: database linkage study. BMJ. 1998;316:426–428.
18.
OyefesoA, ValmanaA, ClancyC, . Fatal antidepressant overdose among drug abusers and non-drug abusers. Acta Psychiatr Scand.2000;102:295–299.
19.
StewartD, GossopM, MarsdenJ. Reductions in non-fatal overdose after drug misuse treatment: results from the National Treatment Outcome Research Study (NTORS). J Subst Abuse Treat.2002;22:1–9.
20.
BohnertAS, McCarthyJF, IgnacioRV, . Misclassification of suicide deaths: examining the psychiatric history of overdose decedents. Inj Prev.2013;19:326–330.
21.
DarkeS, MarelC, MillsKL, . Patterns and correlates of non-fatal heroin overdose at 11-year follow-up: findings from the Australian Treatment Outcome Study. Drug Alcohol Depend.2014;144:148–152.
22.
DarkeS. Opioid overdose and the power of old myths: what we thought we knew, what we do know and why it matters. Drug Alcohol Rev.2014;33:109–114.
23.
PavarinRM, LugoboniF, MathewsonS. Cocaine-related medical and trauma problems: a consecutive series of 743 patients from a multicentre study in Italy. Eur J Emerg Med.2011;18:208–214.
PavarinRM, FiorittiA, FontanaF, . Emergency department (ED) presentation and mortality rate for suicidal behaviour: a follow-up study on attempted suicide referred to the service between January 2004 and December 2010. Crisis. 2014;36(6):406–414.
27.
ClaytonD, HillsM. Statistical Models in Epidemiology. New York: Oxford University Press; 1990.
28.
FrisherM, BaldacchinoA, CromeI, . Preventing Opioid Overdoses in Europe: A Critical Assessment of Known Risk Factors and Preventative Measures. European Monitoring Centre for Drugs and Drug Addiction Technical Paper. Lisbon: European Monitoring Centre for Drugs and Drug Addiction (EMCDDA); 2012.
29.
BohnertAS, IlgenMA, IgnacioRV, . Risk of death from accidental overdose associated with psychiatric and substance use disorders. Am J Psychiatry. 2012;169:64–70.
30.
PowisB, StrangJ, GriffithsP, . Self-reported overdose among injecting drug users in London: extent and nature of the problem. Addiction. 1999;94:471–478.
31.
DarkeS, RossJ, HallW. Overdose among heroin users in Sydney, Australia: I. Prevalence and correlates of non-fatal overdose. Addiction.1996;91:405–411.
32.
FischerB, BrissetteS, BrochuS, . Determinants of overdose incidents among illicit opioid users in 5 Canadian cities. CMAJ. 2004;171:235–239.
33.
PolliniRA, McCallL, MehtaSH, . Responses to overdose among injection drug users. Am J Prev Med.2006;31:261–264.
34.
TracyM, Markham PiperT, OmpadD, . Circumstances of witnessed drug overdose in New York City: implications for intervention. Drug Alcohol Depend.2005;79:181–190.
35.
CopelandL, RobertsonJ, McKenzieJ, . Premature mortality in Scottish injecting drug users: a life-history approach. Scott Med J.2012;57:38–42.
36.
TeessonM, MarelC, DarkeS, . Long-term mortality, remission, criminality and psychiatric comorbidity of heroin dependence: 11-year findings from the Australian Treatment Outcome Study. Addiction. 2015;110:986–993.
37.
DarkeS, DegenhardtL, MattickR. Mortality Amongst Illicit Drug Users. Cambridge, UK: Cambridge University Press; 2007.
38.
DegenhardtL, BucelloC, MathersB, . Mortality among regular or dependent users of heroin and other opioids: a systematic review and meta-analysis of cohort studies. Addiction. 2011;106:32–51.
39.
StrangJ, McCambridgeJ, BestD, . Loss of tolerance and overdose mortality after inpatient opiate detoxification: follow up study. BMJ. 2003;326:959–960.
40.
Bretteville-JensenAL. Illegal drug use and the economic recession. What can we learn from the existing research?Int J Drug Policy. 2011;22:353–359.
41.
JenkinsAJ, KeenanRM, HenningfieldJE, . Pharmacokinetics and pharmacodynamics of smoked heroin. J Anal Toxicol.1994;18:317–330.
42.
BogdanowiczKM, StewartR, BroadbentM, . Double trouble: psychiatric comorbidity and opioid addiction-All-cause and cause-specific mortality. Drug Alcohol Depend.2015;148:85–92.
43.
TobinKE, DaveyMA, LatkinCA. Calling emergency medical services during drug overdose: an examination of individual, social and setting correlates. Addiction. 2005;100:397–404.
