Elsevier

Addictive Behaviors

Volume 34, Issue 9, September 2009, Pages 723-729
Addictive Behaviors

Are non-fatal opioid overdoses misclassified suicide attempts? Comparing the associated correlates

https://doi.org/10.1016/j.addbeh.2009.04.011Get rights and content

Abstract

This paper aimed to determine whether non-fatal opioid overdose and suicide attempts are distinct behaviours by examining the histories of 1500 opioid-dependent individuals. This paper utilised data collected as part of a large retrospective case-control study. Unintentional non-fatal opioid overdoses were more common than suicide attempts (58% vs. 32%). Overall, the correlates associated with a history of attempted suicide only and non-fatal opioid overdose only were different. Drug-related risk behaviours (including high impulsivity, injection of opioids, sedative dependence) were associated with non-fatal opioid overdose; and a history of mental disorders (depression, anxiety disorder, and screening positive for borderline personality disorder (BPD+) were associated with suicide attempts. Additionally, those who reported a history of both behaviours had a more severe clinical profile including excessive drug use, psychological disorders and childhood trauma. The study concluded that non-fatal opioid overdose and attempted suicide are distinct clinically significant problems that require different approaches for prevention. Additionally, if both behaviours are reported a thorough assessment of underlying comorbid problems should be initiated by treatment services.

Introduction

In high income countries, mortality rates among opioid users have been found to be 13 times higher than among the general population (Hulse, English, Milne, & Holman, 1999). Both suicide and opioid overdose contribute to the substantial rates of premature death reported among opioid users (Darke, Degenhardt, & Mattick, 2006). Fatal overdoses and suicides, however, represent only a small proportion of the total number of overdose and suicide events (both fatal and non-fatal) (Darke et al., 2006). Not only has a history of an overdose or a suicide attempt been shown to best predict subsequent mortality, but both behaviours have been associated with substantial morbidity in their own right (Darke et al., 2006, Darke and Ross, 2002). Considering the substantial morbidity and mortality which exists a thorough comparison of the associated correlates is important.

Studies typically suggest around a third of opioid-dependent individuals report a lifetime suicide attempt (Darke and Ross, 2001, Darke et al., 2004, Murphy et al., 1983, Rossow and Lauritzen, 1999). Although limited, research suggests that the risk factors associated with attempted suicide among opioid-dependent individuals include gender (female), psychiatric morbidity, social isolation, family dysfunction, impulsivity and drug dependence (other than opioids) (Darke and Ross, 2002, Dougherty et al., 2004, Maloney et al., 2007).

Research has found that 46% to 70% of all opioid users have experienced at least one non-fatal opioid overdose over their lifetime (Darke and Ross, 2001, Darke et al., 1996, McGregor et al., 1998, Rossow and Lauritzen, 1999, Vingoe et al., 1999, Warner-Smith et al., 2002). Although the majority of fatal opioid overdose cases are males, males and females have similar risk for non-fatal opioid overdose (Bennett and Higgins, 1999, Darke et al., 2006, Darke and Hall, 2003, McGregor et al., 1998).

Contrary to popular belief, non-fatal opioid overdoses have been found to be more common among older, more experienced users (Darke et al., 2006, Darke and Hall, 2003). Polydrug use has also been linked to opioid overdose, with central nervous system depressants, such as alcohol and benzodiazepines, commonly associated with non-fatal opioid overdose cases (Darke et al., 2006, Darke and Hall, 2003, Darke et al., 2005, Warner-Smith et al., 2001). Other risk factors found to be associated with non-fatal opioid overdose cases are injecting as the primary route of administration, and high risk periods, such as post release from prison (Darke et al., 2006, Darke and Hall, 2003, Farrell and Marsden, 2008, Seaman et al., 1998).

There is disagreement concerning the relationship between unintentional non-fatal opioid overdoses and suicide attempts. This disagreement relates firstly, to the extent to which the behaviours can be differentiated based on the observed risk factors, and secondly, the issue of whether research can assess the degree of suicidal intent expressed by opioid-dependent individuals (Cantor, McTaggart, & De Leo, 2001). Research has suggested that around 25% to 30% of opioid users report a history of both a suicide attempt and a non-fatal opioid overdose (Darke and Ross, 2001, Rossow and Lauritzen, 1999, Vingoe et al., 1999). Some studies have found an association between non-fatal opioid overdose and suicide attempts, and have concluded that they can be seen as risk markers for each other (Rossow and Lauritzen, 1999, Vingoe et al., 1999). Additionally, research does suggest that non-fatal overdoses and suicide attempts are predicted by different correlates (Ravndal & Vaglum, 1999). Frequent use of opioids and other opioid use patterns have been found to predict lifetime non-fatal overdose, whereas a diagnosis of borderline personality disorder (BPD) or depression, for example, have been found to predict lifetime suicide attempts (Darke and Hall, 2003, Ravndal and Vaglum, 1999).

A limited number of findings are also consistent with the argument that non-fatal opioid overdoses are not misclassified suicide attempts. Firstly, it has been noted that a high degree of seriousness is generally reported when the suicide attempts of opioid users are examined (Darke & Ross, 2001). Secondly, the finding that opioids are rarely chosen as a method for attempting suicide clearly distinguishes this behaviour from an accidental opioid overdose (Darke and Ross, 2001, Johnsson and Fridell, 1997, Vingoe et al., 1999). Thirdly, a number of studies have found that suicidal intent is not a contributing factor among opioid overdoses (Darke and Ross, 2001, Rossow and Lauritzen, 1999, Vingoe et al., 1999). This view has been disputed, however (Neale, 2000).

Despite the noted importance of assessing non-fatal opioid overdose, few studies have been conducted to carefully assess the issue of whether they are misclassified suicide attempts (Darke et al., 2006). Most studies have examined a few correlates for either suicide attempts or non-fatal opioid overdose, but not a comprehensive list. To our knowledge, only one study (Rossow & Lauritzen, 1999) has compared attempted suicide and non-fatal opioid overdose using mutually exclusive categories. Considering previous studies have demonstrated a substantial overlap exists between the two behaviours (Darke and Ross, 2001, Rossow and Lauritzen, 1999, Vingoe et al., 1999), it is important to also assess the characteristics associated with those who report a history of both behaviours.

This paper goes beyond previous work and compares multiple known correlates for non-fatal opioid overdoses and suicide attempts, including indicators of drug use, psychological disorder and childhood abuse. A comprehensive comparison is essential considering the morbidity, and future risk of mortality associated with both behaviours. This paper aims to determine if it is possible to differentiate correlates for non-fatal opioid overdose and suicide attempts. This aim was addressed by comparing those who reported an overdose only, those who reported a suicide attempt only, and those who reported a history of both behaviours, with those reporting no history of either behaviour.

The specific aims of this paper are:

  • 1.

    to assess the reported prevalence of lifetime suicide attempts and non-fatal opioid overdose among a sample of opioid-dependent individuals;

  • 2.

    to examine the extent to which suicide attempts and opioid overdoses are related among this sample; and

  • 3.

    to compare the correlates associated with attempted suicide and non-fatal opioid overdose.

Section snippets

Procedure

This paper utilised data collected as part of an ongoing, large retrospective case-control study examining genetic and environmental factors (e.g. childhood trauma) contributing to opioid dependence liability. This paper only used data collected from the participants defined as “cases”. A full description of the methods used to obtain control participants has been published in a previous paper (Maloney et al., 2007). Cases were defined as such if they had participated in pharmacotherapy

Sample characteristics

The sample consisted of 1500 opioid-dependent persons. The majority of the sample were male (60%). The male cases were significantly older than the female cases (37.2 versus 35.3, p < 0.001, t1516 = 4.23) and were more likely to report a prison history (66% versus 40%, OR 2.95, 95% CI 2.38–3.65). Males and females were equally likely to report being unemployed at the time of the interview (82% for males, 84% for females), and to report completing only 10 years of education or less (71% for males,

Discussion

Suicide attempts and non-fatal opioid overdose have been examined among opioid-dependent individuals in a number of different studies, with some disagreement on whether they are distinct behaviours. These studies however, rarely include an exhaustive list of correlates associated with either behaviour. Additionally, only one study has compared the two behaviours using mutually exclusive categories (Rossow & Lauritzen, 1999). Overall, the present study found distinct correlates for suicide

Conclusions

Non-fatal opioid overdose and attempted suicide were highly prevalent among this sample of opioid-dependent individuals. The two behaviours had distinct correlates. Non-fatal overdose and suicide attempts are nonetheless related behaviours, and individuals with a history of both behaviours presented with a more complex clinical profile. Prevention of non-fatal overdose and attempted suicide is important to decrease the risk of subsequent mortality. Addressing underlying psychological conditions

Acknowledgements

This study was funded by the National Institute of Drug Abuse (DA 17305). Professor Louisa Degenhardt is the recipient of an Australian National Health and Medical Research Council (NH&MRC) Senior Research Fellowship (#510279). The study was a multi-site study involving teams from the National Drug and Alcohol Research Centre, Queensland Institute of Medical Research, Washington University and Prince of Wales Hospital. The National Drug and Alcohol Research Centre is funded by the Australian

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