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Three Part Question

[In opiate addicts attending following overdose] what are the [predictors of] a [future overdose or death within one year].

Clinical Scenario

An ambulance arrives at the emergency department with a 35 year old male known heroin abuser who has overdosed. The patient dies despite naloxone administration and full attempts to resuscitate him. You treated him for a non fatal overdose 8 months ago and wonder if this could have been a factor in predicting fatal overdose on this occasion.

Search Strategy

Ovid MEDLINE 1966 to May Week 2 2006, EMBASE 1980 to 2006 Week 20, CINAHL 1982 to May Week 2 2006
The Cochrane Library Issue 2 2006
[exp Narcotics/ OR narcotics.mp]. AND [exp Overdose/ OR overdose.mp.] AND [non fatal.ti,ab OR nonfatal.ti,ab] AND [exp Risk factors/ OR risk factors OR exp Prognosis/ OR prognosis.mp.] LIMIT to Humans and English language
Cochrane:: [overdose in Title, Abstract or Keywords] AND [narcotics in Title, Abstract or Keywords]

Search Outcome

50 papers were found 4 of which were relevant to the topic.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Brugal el al. 2002, Spain	2556 subjects treated for heroin dependence in 164 outpatient facilities. Two patient groups of daily and non-daily heroin users.	Prevalence of overdose in emergency care in 12 months before treatment admission. Case control design with OR adjusted by logistic regression and case crossover design.	Most significant risk factors	Injection Risk increases with increasing usual frequency of heroin injection in daily users	Cross sectional design may have survival or recall bias. The definition of overdose is self perceived. The sample may not be representative of all heroin users as street samples often fail to represent newer heroin users. Effect period for heroin was 24 hours and was an overestimation
Seal et al. 2001 USA	1427 heroin injectors from 6 inner city neighbourhoods in San Francisco Bay area.	Retrospective study.	Variables associated with recent overdose.	Drinking 4 or more units of alcohol per day (OR=2.05) and having been arrested three or more times in the past year (OR=2.50).	Targeted sampling techniques were used to recruit heroin users. May be inherent biases in self reported drug use and risk behaviour. Did not specify the type of drug overdose even though heroin injectors were studied.
Gutierrez-Cebollada et al 1992 Spain	76 heroin addicts admitted to the emergency department; 54 because of overdose and 22 seeking urgent medical care for unrelated causes.	Survey and retrospective review.	Factors contributing to non fatal overdose.	Injection High plasma concentrations of total morphine and benzodiazepines	Relatively small sample size. Large difference between sample size of overdose group and non-overdose group. Survey of events relied on self-report.
Dietze et al. 2005 UK	155 patients recruited by paramedics who had been unconscious and responded to naloxone.	Survey about behaviour prior to an overdose, case crossover design.	Risk behaviours prior to overdose as opposed to a non overdose injection.	Increased use of benzodiazepines and alcohol in the 12hrs before overdose Large dose of heroin used	No data for hazard periods in fatal overdose. Amount of heroin used was self reported. Wasn't possible to accurately determine response rate.

Comment(s)

There are a number of variables that are related to fatal and nonfatal overdose. Each study focused on different factors and those with significantly high odds ratios have been included in the results and therefore in the clinical bottom line. No two studies directly backed each other up. It would be useful to follow up the patients to determine if they suffered from further overdoses and if these were fatal.

Clinical Bottom Line

The evidence suggests that the three main factors contributing to overdose are; injecting heroin, chronic misuse of alcohol, and having been arrested more than three times.

Level of Evidence

Level 2 - Studies considered were neither 1 or 3.

References

1. Brugal, M Teresa. Barrio, Gregorio. De, La Fuente et al. Factors associated with non fatal overdose assessing the effect of frequency and route of heroin administration. Addiction 2002:97;319-327.
2. Seal KH. Kral AH. Gee L. et al. Predictors and Prevention of Nonfatal Overdose Among Street Recruited Injection Heroin Users In the San Francisco Bay Area, 1998-1999. American Journal of Public Health. 2001:91;1842.
3. Gutierrez-Cebollada, J. de la Torre, R. Ortuno, J. et al. Psychotropic drug consumption and other factors associated with heroin overdose. Drug and Alcohol Dependence 1994:35;169-174.
4. Dietze, Paul. Jolley, Damien. Fry, Craig. Bammer, Gabriele. Transient changes in behaviour lead to heroin overdose: results from a case-crossover study of non-fatal overdose. Addiction 2005:100;636-642.