NDARC Technical Report No. 164 (2003)


Aims: This report compares trends in the characteristics of accidental and suicidal drug-induced deaths among Australians over the period 1997 to 2001, including demographics, underlying and contributing cause of death and drugs noted in toxic quantities at the time of death.

Method: Cause of death (COD) data, coded according the International Statistical Classification of Diseases and Related Problems – 10th revision (ICD-10), was obtained from the Australian Bureau of Statistics (ABS) for the years 1997 to 2001. The following variables were assessed: sex, age groups, state of residence and underlying and contributing causes of death, as well as drugs noted at the time of death. The ABS definition of drug-induced death (including accidental and suicidal) was utilised.

(a) Trends in accidental and suicidal drug- induced deaths
From 1997 to 2001 there were 7307 drug-induced deaths. Accidental drug-induced deaths (N=5539) were the leading cause of drug-induced deaths in 2001, accounting for 68% of the total number of drug -induced deaths registered followed by suicide (N=1455) with nearly a third (27%). While the number of accidental drug-induced deaths has varied over time (high of 1403 in 1999 to five year low of 710 in 2001) suicidal deaths have remained relatively stable. In 2001 the rate of accidental drug-induced deaths was 46 deaths per million persons aged 15 years and over whereas the suicidal drug-induced death rate which was 18 deaths per million persons aged 15 and over.

(b) Demographic characteristics
The vast majority of accidental deaths were likely to be male (74%) whereas the sex ratio for suicide was roughly equivalent. The largest proportion of accidental deaths occurred within the 25-34 age group, whereas it was the 35-44 year age group for suicidal deaths. In addition there was a greater proportion of suicidal deaths occurring among older persons, with 25% occurring among those aged 55 and over. The majority of accidental and suicidal drug -induced deaths occurred in the most populous Australian jurisdictions (NSW, VIC and QLD).

(c) Underlying causes of death
The most frequently assigned ICD-10 codes for underlying cause of death for accidental deaths were: accidental poisoning due to multiple drugs (X44 - 29%), accidental poisoning due to narcotics (X42 - 23%), opioid drug use disorder (F11 - 23%) and multiple drug use disorder (F19 - 17%). The most frequently applied underlying COD codes for suicidal drug -related deaths were: suicidal poisoning by multiple drugs (X64 -53%), suicidal poisoning by sedative-hypnotics (X61 - 29.4%) and suicidal poisoning by narcotics (X62 - 14%).

(d) Drugs noted in toxic quantities at death
Opioids were more commonly noted among accidental deaths, and antidepressants and sedatives were more common among suicidal deaths: opioids (72% vs. 35%), sedative -hypnotics (24% vs. 35%) and antidepressants (11% vs. 32%). Notably, opioids accounted for the majority of accidental deaths whereas suicidal deaths had opioids, sedativehypnotics and antidepressants present in similar proportions. Accidental drug-induced deaths had higher proportions of alcohol, amphetamines, hallucinogens and cocaine than suicidal drug-induced deaths, whereas suicidal drug-induced deaths had higher proportions of other medications than accidental drug-induced deaths. Accidental opioid deaths were more likely to have opioids alone whereas suicidal opioid deaths were more likely to have sedative -hypnotics, anti-depressants, and non-opioids in combination. When considering all opioid deaths, accidental deaths were more likely to have opioids alone whereas suicidal deaths were more likely to greater proportions of sedative - hypnotics, anti-depressants, and non -opioids in combination with opioids. When considering all sedative-hypnotic deaths, suicidal deaths were more likely to sedative -hypnotics alone and antidepressants and non-opioid in combination whereas accidental deaths where much more likely to have opioids in combination. When considering all antidepressant deaths, suicidal deaths were more likely to have antidepressants alone, whereas accidental deaths were more likely to have opioids and sedative-hypnotics in combination. While accidental opioid-related deaths showed marked decreases since 1999, suicidal drug related deaths showed gradual increases since that time.

(e) Contributing causes of death
Mood disorders were noted in 5% of accidental and 19% of suicidal deaths and acute hepatitis C was noted in 6% of accidental and 1.5% of suicidal deaths. Other contributing diseases were not commonly mentioned.

Discussion: The majority of drug-induced deaths in Australia are noted as accidental. Accidental drug-induced deaths have significantly decreased in Australia from 1999 to 2001, whereas suicidal deaths have remained stable. Opioids, particularly heroin, continue to contribute to the majority of accidental drug-induced deaths, whereas suicidal deaths involve other opioid drugs, benzodiazepines and antidepressants in similar proportions. Males aged 25 - 35 continued to predominate accidental drug-induced deaths in states that are known to have higher rates of heroin use. Suicidal drug related deaths, in contrast, were equally common among males and females, were more concentrated in older age groups and more evenly dispersed across Australia.

Multiple drug deaths were common for both types of deaths. Mono-intoxication was likely for opioids in accidental deaths whereas benzodiazepines and antidepressants were common for suicidal deaths. Licit drugs such as benzodiazepines featured in a notable proportion of both accidental and suicidal drug-induced deaths. A relatively high prevalence of acute hepatitis C was demonstrated for accidental deaths whereas a high prevalence of mood disorders was recorded for suicidal deaths

Accidental and suicidal drug-related mortality are significant public health issues, but clear differences were found in the characteristics of each type of drug-related death, suggesting strongly that they are separate issues and thus require different strategies to address them. Consistent, accurate and timely monitoring of the changes in the patterns of these deaths over time provides an opportunity to inform key stakeholders so as to contribute to appropriate responses to this issue.

Citation: Barker, B. and Degenhardt, L. (2003) Accidental and suicidal drug-induced deaths in Australia 1997-2001, Sydney: National Drug and Alcohol Research Centre.



B. Barker, L. Degenhardt
Date Commenced
24 Oct 2003
Resource Type
Technical Reports