Challenges and approaches to estimating mortality attributable to the use of selected illicit drugs

Factors influencing mortality among alcohol and drug treatment clients in Victoria, Australia: the role of demographic and substance use characteristics

OBJECTIVE

Clinical studies consistently identify alcohol- and drug-related treatment populations as more likely to die prematurely compared with an age-matched general population. However, demographic characteristics and primary drug of concern as predictors of mortality risk following treatment have not been adequately explored. This paper examines relationships between substance use, demographic factors and mortality among alcohol and drug treatment clients.

METHOD

A retrospective cohort incorporating 7 years of data was utilised to examine mortality outcomes in the 2 years following treatment among Victorian clients recorded on the Alcohol and Drug Information Service (ADIS) database by linking partial client identifiers with the National Death Index (NDI). A cohort of 18,686 clients engaged in at least one course of treatment over a 12-month period was included. Analysis was of crude and standardised mortality rates across client groups in terms of the presenting drug of concern for treatment and demographic characteristics.

RESULTS

A higher risk of premature death was associated with older age, being male, not being employed, living alone, medical and psychiatric comorbidity, recent injecting, and a history of intensive drug treatment access. Alcohol treatment clients had the worst prognosis. After adjustment for client characteristics, alcohol treatment clients experienced a significantly higher rate of death compared with other clients.

CONCLUSIONS

Findings from these previously unexplored data highlight the need to increase awareness of the range and magnitude of risks associated with harmful alcohol use, and to identify approaches to enhance treatment effectiveness to reduce negative outcomes following treatment for populations at elevated risk of harm.

Mortality associated with illegal drug use among adults in the United States

OBJECTIVES

To examine all-cause and cause-specific mortality over a 15-year follow-up period in relation to at-baseline reported lifetime use of illegal drugs from five classes (marijuana, cocaine, heroin, hallucinogens, and inhalants) among adults in the United States (US) household population.

METHODS

The study involved 20,983 sample adults who responded to the 1991 National Health Interview Survey Drug and Alcohol Use supplemental questionnaire and also met the eligibility criteria for mortality follow-up. Cox proportional hazards models were estimated to examine the relationships.

RESULTS

Adults who at baseline reported lifetime heroin use were at significantly higher risk of all-cause death over the follow-up period (hazard rate ratio or HR = 2.02; 95% confidence interval or CI 1.26-3.23), compared with those who did not report using drugs from any of the five classes, even after adjusting for age, sex, race, education, marital status, cigarette smoking status, and alcohol use status. Those who at baseline reported lifetime cocaine (no heroin) use had a significantly higher rate of death associated with human immunodeficiency virus diseases over the follow-up period than nonusers of drugs from any of the five classes. Several limitations of the analysis are discussed.

CONCLUSIONS

Further research is needed to understand and track the elevated mortality associated with illegal drug use and the correlates of drug-poisoning deaths.

Global burden of disease from alcohol, illicit drugs and tobacco

The use of alcohol, tobacco and illicit drugs entails considerable burden of disease: in 2000, about 4% of the global burden as measured in disability adjusted life years was attributable to each alcohol and tobacco, and 0.8% to illicit drugs. The burden of alcohol in the above statistic was calculated as net burden, i.e. incorporating the protective health effects. Tobacco use was found to be the most important of 25 risk factors for developed countries in the comparative risk assessment underlying the data. It had the highest mortality risk of all the substance use categories, especially for the elderly. Alcohol use was also important in developed countries, but constituted the most important of all risk factors in emerging economies. Alcohol use affected younger people than tobacco, both in terms of disability and mortality. The burden of disease attributable to the use of legal substances clearly outweighed the use of illegal drugs. A large part of the substance-attributable burden would be avoidable if known effective interventions were implemented.

Estimating the total mortality among problem drug users

This paper's objective is to develop a method to estimate the total mortality among problem drug users. The total mortality is given by a base rate of mortality not related to drugs and the deaths that are directly and indirectly related to drugs. A fatal poisoning by drugs (overdose) is directly related to drugs, whereas a casualty due to a drug-related disease or a drug-related accident is indirectly related to drugs. As an example of a method to estimate the total mortality, the results from a cohort study among methadone patients in Amsterdam were projected on the whole population of problem drug users in The Netherlands. Due to differences between the problem drug users in Amsterdam and the rest of the country, adjustments were required. It was found that an initial estimation did not require adjustment for injection behavior and gender but did require adjustment for age and the percentage of HIV infection. In a first unadjusted estimation, the total number of deaths among problem drug users in The Netherlands in 2001 was estimated at 606 deaths. After adjustment for age, the estimated mortality decreased to 573 deaths, and after adjustment for HIV infection, this estimation again decreased to 479 deaths. From the ultimately estimated mortality, 11% was considered to be not related to drugs, 23% was attributed directly to drugs, and 66% was attributed indirectly to drugs. The number of direct deaths, as estimated by this method, falls in the same order of magnitude as the number extracted from the Causes of Death Statistics, when selecting cases according to the Drug-Related Deaths Standard as established by the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA). Further cross-validation with other measures will be needed to assess the accuracy of the method, the limitations of which are discussed with respect to stipulating directions for future research.

Avoidable burden of disease: conceptual and methodological issues in substance abuse epidemiology

Determining the proportion of avoidable disease burden attributable to substance use is important for both policy development and intervention implementation. Current epidemiological theory has in principle provided a method to estimate avoidable burden of disease and the available statistical tools can provide first rough estimates. The method described in this paper, and its statistical procedures, are exemplified to estimate avoidable burden of tobacco-related disease in Canada. However, further effort is needed to find solutions in the methodological details, namely exposure measurement, risk factor multidimensionality, estimation of changes in exposure distribution over time, and estimation of risk relationships from multiple exposures changing over time with multiple endpoints (causal webs). The impetus to begin refining methods to obtain better starting points for estimating avoidable burden of disease is obvious and should be carried through in order to see real changes through evidence-based policy and intervention.

Interpreting changes in heroin supply in Melbourne: droughts, gluts or cycles?

In this Harm Reduction Digest Paul Dietze and John Fitzgerald provide another possible way of understanding what has come to be referred to as Australia's heroin 'drought'. They examine evidence from Melbourne, Victoria and suggest that the apparent downturn in heroin availability in 2000 may, in part, be the result of an end of a heroin 'glut' and that perceptions of this phenomenon may be coloured by the development of more sophisticated indicators of the heroin market. They conclude with claims that the reasons for the reduction in drug consumption and adverse health outcomes, such as those attributed to interdiction, are thus premature