Substance use, dependence and treatment seeking in the United States and Australia: A cross-national comparison
Introduction
Substance abuse and dependence leads to a significant burden on many societies. Cross-national comparisons are important in understanding this burden. The introduction of the Diagnostic and Statistical Manual of Mental Disorders, 3rd Edition (American Psychiatric Association, 1980) in 1980 revolutionised both psychiatry and psychiatric epidemiology and made international comparisons a possibility. Since then there have been a number of large-scale epidemiological studies of the prevalence and correlates of psychiatric conditions including drug and alcohol dependence. The first such major study was the ECA, conducted in five states, and involving structured interviews with 20,000 individuals, across the United States (Robins and Regier, 1991). There have now been a number of replications of the ECA, conducted both in the U.S. (Kessler et al., 1994) and other countries (e.g. Ross, 1995). These studies have confirmed the general pattern of results evident from the ECA: alcohol and drug dependence are common within the general population and only a minority of those meeting diagnostic criteria seek treatment for their condition.
One of the strengths of these investigations is the application of rigorous methodologies, which allows the potential for comparisons across studies and countries. Even though there have been an ever growing number of epidemiological surveys of substance use disorders, to date there have been relatively few cross-national comparisons of the prevalence and correlates of alcohol and drug use disorders. The few well-conducted comparisons, which have been undertaken consistently find evidence that drug dependence is more prevalent in the U.S. than other countries (Vega et al., 2002, Maxwell, 2003, Furr-Holden and Anthony, 2003). In contrast, a number of publications (Chen et al., in press, Anthony et al., 1994, Swift et al., 2001a, Swift et al., 2001b, Degenhardt et al., 2001) indicate that cannabis dependence is more prevalent in Australia and New Zealand (Poulton et al., 1997) compared to American populations (Anthony, in press). Interpretation of these crude comparisons is compromised by differences between the samples (for example, birth cohort follow-up in New Zealand compared to cross-sectional sampling in the USA and differing ages of the samples). The present paper conducts new analyses of existing data to derive more directly comparative estimates of drug use disorders in Australia and the USA.
The value of such cross-national comparisons has long been recognised (Kessler et al., 1997) and includes: assessment of the impact of existing health care systems and social and cultural factors on both the prevalence and service response to mental health and substance dependence. For example, the availability of different drugs or restrictions on access to alcohol across countries may affect prevalence of use and dependence. Similarly, health service utilisation by people with alcohol or drug use disorders may be influenced by the structure of health care services.
The current study reports a cross-national comparison of the prevalence, correlates and treatment seeking for substance dependence in Australia and the United States of America. Comparison between these countries are of value as, although culturally the two countries appear quite similar (they are both relatively young countries, English is the first language of the majority of people in both countries and they both enjoy high standards of living and access to health care, there are also a number of important differences between the two countries:
- 1.
Rates of alcohol use appear to vary between the two countries with alcohol use being more accepted and widespread in Australia than in the United States (Maxwell, 2003).
- 2.
Legal and policy approaches towards the reduction of drug use and the avoidance of drug related harm vary between the two countries: compared with a more prohibitionist stance in the United States, Australian alcohol and drug health service policy has more of a focus on harm reduction. Specific differences between the two countries include (but are not limited to) a higher legal drinking age in many of the United States (21 in USA versus 18 in Australia) and the more widespread availability of needle and syringe programs in Australia than in the United States (Drucker et al., 1998).
- 3.
Substantial differences in the organisation and funding of health care services with Australia having a universal health care system funded through taxation while the United States system relies more heavily on private funding.
The aim of this paper is to present the 12 months DSM-IV prevalence of alcohol and drug use disorders in the Australian general population, and to compare these findings with the United States data from the National Comorbidity Survey (NCS).
Section snippets
Method
This study presents a new analysis of data from both the NCS (Kessler et al., 1994) and the NSMHWB (Andrews et al., 1999, Australian Bureau of Statistics, 1998) on the prevalence, correlates and treatment seeking associated with DSM-IV substance use and substance dependence in the United States of America and Australia. Detailed descriptions of the U.S. and Australian surveys are available elsewhere (Anthony et al., 1994, Teesson et al., 2000, Hall et al., 1998, Teesson et al., 2002). These
Prevalence of substance use in the past 12 months
Table 1 shows that recent alcohol use is higher in Australian adults, compared with Americans. Within the Australian sample, 77.2% of respondents aged 18–54 reported consumption of at least 12 drinks of alcohol in the year preceding the NSMHWB (1997), compared with 46.3% of Americans in the 12 months preceding the NCS (1990/1991).
The prevalence of use of the drugs assessed was considerably lower than alcohol use, but similar, in both countries. An estimated 10.8% of Australians and 11.9% of
Discussion
The major finding from this comparison, with a few exceptions, is the consistency of rates and patterns of 12-months dependence on alcohol and drug dependence in the U.S. and Australia. Both surveys reported a higher prevalence of substance dependence in males than females, and the prevalence peaked in young adults and declined linearly with age. Importantly, the lack of any significant interaction between the common correlates of alcohol and other drug dependence and country indicates that the
Conclusions
The drug dependence conditional prevalence rates differ considerably between the USA and Australia, yet the alcohol dependence conditional prevalence rates are very similar. The differences are so marked that the small differences in methodology are unlikely to explain the findings. The findings raise doubts as to the generalizability of research findings regarding risk factors cross-nationally and for the potential for targeted interventions based on identification of risk factors to be
Acknowledgements
The National Survey of Mental Health and Well-being was a major piece of applied social research that involved the cooperation of a large number of individuals and organisations that we wish to thank. The design, development, and conduct of the survey were funded by the Mental Health Branch of the Commonwealth Department of Health and Family Services.
The development and testing of the computerised survey instrument was undertaken by Gavin Andrews, Lorna Peters, and other staff at the Clinical
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