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

A number of unique challenges are faced when attempting to estimate mortality attributable to illicit drugs. The hidden nature of illicit drug use creates difficulties in quantifying the prevalence of such use; identifying adverse health effects associated with exposure, and calculating the risk of these effects. The use of cohort studies of drug users allows the identification of causes of mortality associated with drug use and the determination of the risk of these causes. This risk estimate can then be used in conjunction with estimates of the prevalence of drug use to, extrapolate the burden of mortality. We identify a number of such studies and present some solutions to the major challenges faced when attempting to estimate the global burden of mortality attributable to illicit drug use. Copyright (C) 2001 S. Karger AG, Basel.

Is cannabis a gateway drug? Testing hypotheses about the relationship between cannabis use and the use of other illicit drugs

We outline and evaluate competing explanations of three relationships that have consistently been found between cannabis use and the use of other illicit drugs, namely, ( 1) that cannabis use typically precedes the use of other illicit drugs; and that ( 2) the earlier cannabis is used, and ( 3) the more regularly it is used, the more likely a young person is to use other illicit drugs. We consider three major competing explanations of these patterns: ( 1) that the relationship is due to the fact that there is a shared illicit market for cannabis and other drugs which makes it more likely that other illicit drugs will be used if cannabis is used; ( 2) that they are explained by the characteristics of those who use cannabis; and ( 3) that they reflect a causal relationship in which the pharmacological effects of cannabis on brain function increase the likelihood of using other illicit drugs. These explanations are evaluated in the light of evidence from longitudinal epidemiological studies, simulation studies, discordant twin studies and animal studies. The available evidence indicates that the association reflects in part but is not wholly explained by: ( 1) the selective recruitment to heavy cannabis use of persons with pre-existing traits ( that may be in part genetic) that predispose to the use of a variety of different drugs; ( 2) the affiliation of cannabis users with drug using peers in settings that provide more opportunities to use other illicit drugs at an earlier age; ( 3) supported by socialisation into an illicit drug subculture with favourable attitudes towards the use of other illicit drugs. Animal studies have raised the possibility that regular cannabis use may have pharmacological effects on brain function that increase the likelihood of using other drugs. We conclude with suggestions for the type of research studies that will enable a decision to be made about the relative contributions that social context, individual characteristics, and drug effects make to the relationship between cannabis use and the use of other drugs.

Quantifying the use of the statin antilipemic drugs: Comparisons and contrasts between Nova Scotia, Canada, and Queensland, Australia

Background: jurisdictions are developing public drug insurance systems to improve access to pharmaceuticals, cost-effective prescribing, and patient health and well-being. We compared 2 Jurisdictions with different pharmaceutical policies to determine prescribing patterns for 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (le, statins). Objective: The aim of this work was to investigate the feasibility of using available prescription admimstrative databases to compare the use of statins in Queensland, Australia, and in Nova Scotia, Canada. Methods: Data from the Nova Scotia Pharmacare Program and the Health Insurance Commission in Australia were used to obtain dispensing data. Utilization was compared for the 5-year period from 1997 through 2001, using the World Health Organization anatomic therapeutic chemical/defined daily dose (DDD) system. Results: In the year 2001, there were 177,000 beneficiaries in the public drug plan in Nova Scotia (62% aged ≥ 65 years old) and 960,000 concession beneficiaries (pensioners and social security recipients, 61% aged ≥ 65 years) in Queensland. These 2 groups were comparable. The overall utilization of statin medications increased steadily in both areas over the study period, from 50 to 205 DDD/1000 beneficiaries per day. Comparison of the 2 growth lines showed no statistically significant differences in overall statin use despite differences in brand availabilities and policies about prescribing. In the year 2001, atorvastatin was the most commonly prescribed statin in both areas, comprising 46% of statin use in Nova Scotia and 51% in Queensland. Mean doses of each statin prescribed were slightly above the DDDs. Expenditure on statins per 1000 beneficiaries and per DDD were similar in each jurisdiction, being slightly higher in Nova Scotia. Conclusions: Despite differences in pharmaceutical reimbursement systems, use of the statins was similar in Nova Scotia and Queensland. The feasibility of the methodology was demonstrated. Future studies, including comparisons of drug utilization for other classes of drugs for which drug policies may be divergent (eg, different pricing structures or prior authorization requirements), or for which less evidence for appropriate use is available, may be useful. © 2005 Excerpta Medica, Inc.

Changes in use of disease-modifying anti-rheumatic drugs in Australia over the period 1992-2004

Purpose Evidence is growing that early use of disease-modifying anti-rheumatic drugs (DMARDs) and combinations of these drugs provide optimal care for people with rheumatoid arthirits. The aim of this study was to describe objectively the pattern of consumption of DMARDs in the Australian community (community-based prescribing, specialist and general practitioner) 1992-2004, and to compare this with prescribing patterns reported in other countries. Method Dispensing statistics from the Pharmaceutical Benefit Scheme (PBS-Australia's universal prescription subsidy scheme) were analysed and temporal trends evaluated. Drug consumption was calculated as the number of dispensed defined daily doses (DDD)/1000 inhabitants/day (WHO ATC/DDD classification 2005). Results The consumption of DMARDs in the Australian community increased steadily from 2.6 DDD/1000 inhabitants/ day in 1992 to 5.5 DDD/1000 inhabitants/day. Over the period 1992-2004, methotrexate (MTX) was the most commonly used DMARD (from 0.6 to 3.0 DDD/1000 inhabitants/day). Consumption of gold (parentcral and oral) and penicillamine declined during this time. The inclusion of leflunomide on the PBS in 2000 contributed to the increase in DMARD usage. Conclusion Use of DMARDs within the Australian community has increased in recent years, coinciding with the change in guidelines for therapy for rheumatoid arthritis (RA) to earlier use of DMARDs and the more common use of combinations. This study used DDD methodology to quantify trends for DMARD consumption and these trends are broadly consistent with international prescribing patterns assessed using different methodologies. Copyright (c) 2006 John Wiley & Sons, Ltd.

The development of an early warning system to detect trends in illicit drug use in Australia: The illicit drug reporting-system

Appropriate ways to monitor the availability and use of illicit drugs were examined. Four methods were tested concurrently: (1) a quantitative survey of injecting drug users, (2) a qualitative key informant study of illicit drug users and professionals working in the drug field, (3) examination of existing sources of survey, health and law enforcement data and (4) an ethnographic study of a high risk group of illicit drug users. The first three methods were recommended for inclusion in an ongoing national monitoring system, enabling the collection of both quantitative and qualitative data on a range of illicit drugs in a relatively brief, quick and cost-effective manner. A degree of convergent validity was also noted among these methods, improving the degree of confidence in drug trends. The importance of injecting drug users as a sentinel population of illicit drug users was highlighted, along with optimal methods for qualitative research.

Cannabis use and psychosis

This paper reviews evidence on two hypotheses about the relationship between cannabis use and psychosis. The first hypothesis is that heavy cannabis use may cause a cannabis psychosis-a psychosis that would not occur in the absence of cannabis use, the symptoms of which are preceded by heavy cannabis use and remit after abstinence. The second hypothesis is that cannabis use may precipitate schizophrenia, or exacerbate its symptoms. Evaluation of these hypotheses requires evidence of an association between cannabis use and psychosis, that is unlikely to be due to chance, in which cannabis use precedes psychosis, and in which we can exclude the hypothesis that the relationship is due to other factors, such as other drug use, or a personal vulnerability to psychosis. There is some clinical support for the first hypothesis. If these disorders exist they seem to be rare, because they require very high doses of THC, the prolonged use of highly potent forms of cannabis, or a pre-existing (but as yet unspecified) vulnerability. There is more support for the second hypothesis, in that a large prospective study has shown a linear relationship between the frequency with which cannabis has been used by age 18 and the risks over the subsequent 15 years of a diagnosis of schizophrenia. It is still unclear whether this means that cannabis use precipitates schizophrenia, whether it is a form of self-medication, or whether the association is due to the use of other drugs, such as amphetamines, which heavy cannabis users are more Likely to use. There is stronger evidence that cannabis use can exacerbate the symptoms of schizophrenia. Mental health services should identify patients with schizophrenia who use alcohol, cannabis and other drugs and advise them to abstain or to greatly reduce their drug use.

Cannabis use and psychosis: a review of clinical and epidemiological evidence

Objective: This paper evaluates evidence for two hypotheses about the relationship between cannabis use and psychosis: (i) that heavy cannabis use causes a 'cannabis psychosis', i.e, a psychotic disorder that would not have occurred in the absence of cannabis use and which can be recognised by its pattern of symptoms and their relationship to cannabis use; and (ii) that cannabis use may precipitate schizophrenia, or exacerbate its symptoms. Method: Literature relevant to drug use and schizophrenia is reviewed. Results: There is limited clinical evidence for the first hypothesis. If 'cannabis psychoses' exist, they seem to be rare, because they require very high doses of tetrahydrocannabinol, the prolonged use of highly potent forms of cannabis, or a preexisting (but as yet unspecified) vulnerability, or both. There is more support for the second hypothesis in that a large prospective study has shown a linear relationship between the frequency with which cannabis had been used by age 18 and the risk over the subsequent 15 years of receiving a diagnosis of schizophrenia. Conclusions: It is still unclear whether this means that cannabis use precipitates schizophrenia, whether cannabis use is a form of 'self-medication', or whether the association is due to the use of other drugs, such as amphetamines, which heavy cannabis users are more likely to use. There is better clinical and epidemiological evidence that cannabis use can exacerbate the symptoms of schizophrenia.

Allowing the medical use of cannabis

Cannabis has been advocated as a treatment for nausea, vomiting, wasting, pain and muscle spasm in cancer, HIV/AIDS, and neurological disorders. Such uses are prohibited by law; cannabinoid drugs are not registered for medical use in Australia and a smoked plant product is unlikely to be registered. A New South Wales Working Party has recommended granting exemption from prosecution to patients who are medically certified to have specified medical conditions. This proposal deserves to be considered by other State and Territory governments.