In these analyses, we found a history of non-fatal overdose was common among Thai IDU, with more than one-quarter of the sample (29.8%) reporting a previous overdose event. The predominant drug implicated in overdose events was heroin, with the majority of individuals reporting injecting heroin before their last overdose and every individual with a history of overdose also reporting a history of heroin use. In a multivariate model, a history of overdose was linked to poly-drug use and incarceration. Most of the participants also reported experience witnessing an overdose (67.9%) and the most common responses included performing first aid and taking the victim to a hospital. When asked how to manage an overdose, the most common responses included performing first aid or artificial respiration and injecting salt water.
The level of non-fatal overdose observed in this sample is on the lower end of the range of estimates calculated in similar studies of community-based IDU in Baltimore, Maryland (24.7%) [21
]; London, England (37.8%) [22
] and San Francisco, California (47.9%) [23
]. We are unable to determine if this comparatively lower level is the result of a lower incidence of overdose among Thai IDU or a greater risk of death at each overdose event. Several points of evidence support a contribution from the latter effect, including the high prevalence of witnessing overdoses; the pervasive level of misperceptions concerning how to manage an overdose; the high prevalence of overdose as the reported cause of death among Thai IDU in two HIV vaccine preparatory studies [24
]; and the ongoing violent crackdown by Thai police against drug users, a phenomenon linked to a greater risk of overdose mortality in other settings [26
Our findings identify the need for enhanced education for Thai IDU to prevent and manage overdoses. Specifically, approximately half of respondents indicated they did not have the information required to prevent and manage overdoses. This lack of knowledge was reflected in the substantial proportion of participants reporting inappropriate responses, including injecting the sufferer with salt water. Given that witnessing an overdose was common in this setting and fatal overdoses typically take hours to develop [29
], the need to improve peer responses is clear. Inappropriate or suboptimal responses by IDU to overdose are not uncommon and have been reported from a number of settings [26
]. However, overdose management education has been shown to be effective at training IDU to respond appropriately to overdose [26
These findings also support the distribution of naloxone to drug users. Naloxone, an opiate antagonist, is the standard treatment used by healthcare professionals in resuscitation efforts following opioid overdose. Programs to train IDU in overdose response alongside distribution of naloxone would likely benefit Thai IDU, given that opiates were the most common class of drugs reported by this sample prior to their last overdose. Additionally, given pervasive anti-drug user stigma [33
] and the ongoing violent campaign by police [35
], many IDU may be unwilling to seek professional health care in the event of an overdose. Evaluations of analagous interventions in Chicago [36
], New York City [10
] and San Francisco [37
] have observed positive impacts, including hundreds of successful peer opioid overdose resuscitations. Currently, naloxone is only available to IDU in Thailand at the MSHRC.
In the multivariate model, a history of incarceration was independently associated with ever overdosing. This is in line with previous analyses that have identified a high risk of overdose, including fatal overdose, associated with incarceration, especially in the first weeks following release from detention [38
]. In the Thai context, previous studies have described the links between exposure to correctional environments and an elevated risk of HIV infection among IDU [40
]. Our findings add evidence supporting the need for an expansion of harm reduction opportunities in Thai correctional settings, such as substitution therapies, shown effective at reducing HIV risk behaviours [42
] and improving outcomes post-release [43
While the implementation of peer-based interventions might lower the incidence and severity of overdose events among Thai IDU, our findings also have implications for other social- and structural-level policies. In particular, our findings are another example of how the reliance on enforcement-based strategies to respond to illicit drug use can produce further drug-related harms [44
]. Just as some observers have identified deaths resulting from the Thai government's crackdown on drug users [35
], our findings describe how criminal justice interventions can increase the risks associated with overdose events. We echo other authors who have credited the country's successful efforts to reduce the incidence of sexually-transmitted HIV infections to the government's adoption of evidence-based policies [41
] and urge a similar pragmatic initiative to replace dominant enforcement- and suppression-based policies with harm reduction programmes.
Our study has limitations. First, cross-sectional analyses are unable to determine the temporal relationship between outcome and exposure. Second, although our measures are based on self-reports from IDU, we do not believe participants would have been more or less likely to report a history of overdose based on the covariates we examined. Finally, our sample of IDU was not recruited at random and thus may not necessarily generalize to other samples of IDU in Thailand or other settings.