Current Drug Abuse Reviews - Volume 6, Issue 2, 2013

Current data on the epidemiology of recreational drug use is largely based on population and self-population surveys of drug use. In addition, increasingly, particularly for novel psychoactive substances, data collected from web monitoring systems is used to collect information on early trends in the use of NPS and the drugs available to users. All of these indicators rely on users self-report of the drug(s) that they are using, or more accurately the drugs that they perceive they are using. Numerous recent studies have demonstrated significant variation in the content of both classical recreational drugs and novel psychoactive substances. The technique of waste-water analysis has allowed estimation of population level use of a number of established recreational drugs such as cocaine and MDMA. However this technique is limited for novel psychoactive substances because of limitations in the knowledge of the stability and metabolism of these compounds. Our group has developed a technique that involves the collection and analysis of pooled-urine from standalone portable urinals and demonstrated that this technique can be used to detect the use of both classical, established recreational drugs and novel psychoactive substances. We discuss this technique in this paper and the ways in which this can be further developed to allow detection of use of new NPS and trends in use of these substances over time and across geographical regions.

Data from surveys of arrestees and the household population in the U.S. suggest there is only modest overlap among demand for the big three expensive illegal drugs (cocaine/crack, heroin, and methamphetamine). In particular, the number of chronic users of these substances (defined as consuming on four or more days in the previous month) is only about 10% below a naïve estimate obtained by simply summing the numbers of chronic users for each of the three substances, while ignoring polydrug use entirely. This finding does not gainsay that polydrug use is common or important. One would estimate greater overlap if one adopted a more expansive definition of polydrug use (e.g., has the individual ever used another substance at any time in their life) or a more expansive list of substances (e.g., allowing marijuana or alcohol to count as one of the substances makes polydrug use seem much more common). However, it does suggest that when focusing on the illegal drug markets that generate the most crime, violence, and overdose death in the U.S., one can usefully think of three more or less separate markets populated at any given time by largely distinct populations of drug users.

Cocaine supplies to and within Australia increased after 2006-07, and there is some evidence that cocaine demand may also have risen. However, the extent, nature and public health implications of any changes in cocaine demand remain unclear. Equally unclear, is whether such changes may have been fuelled by declines in two of Australia’s other stimulant markets. We examined general population trends in cocaine use and harmful practices and use of related stimulants between 1998 and 2010, and conducted age-period-cohort analyses using five repeated cross-sections of Australia’s National Drug Strategy Household Survey. The results indicate past year cocaine use prevalence has increased significantly since 2004, to its highest point in the past 12 years; 2.1% in 2010. But frequency of cocaine use has not increased. Moreover, most harmful practices (injecting, high-quantity use) have remained stable. Changes in the cocaine market appear related to changes in the Australian methamphetamine and ecstasy markets, including declining purity of ecstasy. For example, the cohorts of people most likely to exhibit recent cocaine use were also most likely to have used ecstasy and methamphetamine (those born from 1976 to 1984). The findings indicate that an increase in cocaine demand does not necessarily lead to substantial increases in public health harm: and indeed that the public health implications from the recent increase are likely to be negligible. Moreover, the findings suggest changes to either ecstasy or methamphetamine supply may lead to more shifts in demand for Australia’s cocaine market.

Background: The hidden nature of the use of opioids, amphetamines, cocaine, and cannabis (the most commonly used and studied illicit drugs) precludes the accurate estimation of how many people use them and further important aspects of the use. Among the many aspects of drug use, the permanence times in specific drug using states related to the lifestyles of the various sub populations of users are of interest, per se, as essential components of estimates relating prevalence and incidence of drug use and for evaluating policies. Methods: Several administrative databases and surveys collected in Italy and in different EU countries concerning different sub-populations of drug users were analysed to estimate the permanence time in a specific drug using state and the stages of a typical drug-using career. Results: Cannabis is mostly the first illegal substance used. The age at onset corresponds to the very beginning of adolescence and various sources indicate that this onset happens earlier for men than for women. For problematic drug users, the switch from cannabis to heavy drugs happens within a rather narrow period of time, within 5-6 years from the first use of cannabis, along with the first episode of drug dealing. The latency period distribution estimated from different data sources is quite stable, with men presenting longer latency periods than women. Conclusions: The comparative analysis of several data sources allowed a more complete overview of the different subpopulations on the drug scene and provides interesting data to understand and to estimate parameters for dynamic models of drug use.

The size of the illicit drug market is an important indicator to assess the impact on society of an important part of the illegal economy and to evaluate drug policy and law enforcement interventions. The extent of illicit drug use and of the drug market can essentially only be estimated by indirect methods based on indirect measures and on data from various sources, as administrative data sets and surveys. The combined use of several methodologies and data sets allows to reduce biases and inaccuracies of estimates obtained on the basis of each of them separately. This approach has been applied to Italian data. The estimation methods applied are capture-recapture methods with latent heterogeneity and multiplier methods. Several data sets have been used, both administrative and survey data sets. First, the retail dealer prevalence has been estimated on the basis of administrative data, then the user prevalence by multiplier methods. Using information about behaviour of dealers and consumers from survey data, the average amount of a substance used or sold and the average unit cost have been estimated and allow estimating the size of the drug market. The estimates have been obtained using a supply-side approach and a demand-side approach and have been compared. These results are in turn used for estimating the interception rate for the different substances in term of the value of the substance seized with respect to the total value of the substance to be sold at retail prices.

Several methods for estimating drug use incidence, that have been used in the literature or that could be used, having been used in a different framework, are described and commented. The applicability of the different methods depends on available data and knowledge about relevant parameters. The many similarities between drug use incidence estimation and estimation of disease incidence are highlighted, but also the distinguishing aspects that make drug use incidence estimation a challenge to standard statistical methods.

This contribution provides an overview of different approaches used to analyse drug policies within and across countries. Besides the great number of cost of illness studies which have contributed to the assessment of health harms and risks associated to the drug use, most of the recent efforts have focused on the creation of synthetic indices to classify countries around the world or to evaluate particular law enforcement policies in some countries. This is probably due to a general lack of comparable data across countries. The wide variety of budgetary practices in the drugs field in Europe contributes to the problems that exist in estimating drug-related public expenditure. These heterogeneous accounting practices, together with the complexity of the drug phenomenon and the multiplicity of perspectives on the issue, strongly constrains the possibility of economically evaluate and compare drug laws across countries.

Demand-based estimates of total cannabis consumption rarely consider differences among different user types and variation across countries. To describe cannabis consumption patterns and estimate annual consumption for different user types across EU Member States, a web survey in Bulgaria, Czech Republic, Italy, the Netherlands, Portugal, Sweden and United Kingdom (England & Wales) collected data on cannabis use patterns from 3,922 persons who had consumed cannabis at least once in the past year. They were classified into four groups based on their number of use days in the past 12 months: infrequent users or chippers (<11 days), occasional users (11-50 days), regular users (51-250 days) and intensive users (>250 days). User type specific data on typical amounts consumed were matched with data on numbers of users per user type estimated from existing population surveys, taking differences in mode of consumption, age and gender into account. Estimates were supplemented with data from populations of problem users to compensate for under coverage. Results showed remarkably consistent differences among user groups across countries. Both the average number of units consumed per typical use day and the average amount of cannabis consumed per unit increased across user types of increasing frequency of use. In all countries except Portugal, intensive users formed the smallest group of cannabis users but were responsible for the largest part of total annual cannabis consumption. Annual cannabis consumption varied across countries but confidence intervals were wide. Results are compared with previous estimates and discussed in the context of improving estimation methods.

A comparative analysis of three different estimation methods of cocaine use in Milan, Italy, is carried out, including an analysis of the size and trends of the underlying reference population. The three cocaine use estimates are derived from wastewater analysis, a “street” survey and one-source capture-recapture analysis of administrative sanctions for drug possession. All three data sources span several years during the decade 2000-2010. For each method, assumptions and limitations are discussed. It is concluded, although the amount of data regarding cocaine use in Milan during the years 2000-2010 is considerable, that none of the estimates is completely reliable, mainly because of the many assumptions needed for inference to the whole community, that all three estimates however agree on a substantial reduction in cocaine use and users between the years 2007 and 2010. The recently developed wastewater analysis technique yields estimates comparable to those derived from the street based survey, while capture-recapture analysis of administrative data on identification by law enforcement agencies as cocaine user probably targets only a subpopulation of all users.