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27 January 2009 - Press release

Heroin, a drug in decline?

A study by IMIM shows the evolution of the incidence of heroin use in Spain during the last 35 years

An extensive report to be published this February in the prestigious journal Addiction shows the results of a study about the evolution of the incidence of heroin use in Spain from 1971 to 2005. This exhaustive work, spanning 35 years of the history of an addiction that creates significant public health problems and which became a true epidemic in Spain in the 1970s and 1980s, included the analysis of data from 167,753 individuals with a heroin addiction problem.

The research was led by the Drug Abuse Epidemiology research group at the Municipal Institute of Medical Research (IMIM-Hospital del Mar) in close collaboration with researchers from the University of Barcelona, the Spanish Drug Observatory, the Biomedical Research Centre Network for Epidemiology and Public Health (CIBERESP), the Murcia Regional Drug Observatory and the Catalan Public Health Agency.

The report reveals that the number of people who begin to use heroin in Spain is currently less than at the beginning of the 1970s, and 95% lower with respect to the period between 1979 and 1982, when the index of new heroin users among the population (from 15 to 44 years of age) was at its highest. The figures fell from 190 new heroin users per 100,000 inhabitants in 1980 to 8 new users per 100,000 inhabitants in 2005. In addition, the research team reports that addiction is on average five times more frequent in men than in women. After the end of the 1980s, perhaps due to hepatitis C infections and the emerging risk of contracting HIV, administration by injection was replaced more and more by inhalation. The average age at first use was 21 and the average age at beginning treatment for drug dependency was 28.

According to Antònia Domingo, coordinator of the study: “It stands out that incidence (new users) began to decrease before there was awareness of the seriousness of the epidemic and, in consequence, before any health action was undertaken. The arrival of other substances considered less dangerous by society than heroin such as cocaine and ecstasy probably contributed to this, as well as the severe consequences the HIV epidemic had in Spain”. The researchers observe, however, that since 2005 the tendency towards a drop in treatments for heroin use has stabilised. What course this change takes and how this addiction will develop should be looked at in future studies.

Knowing the index of new heroin users is fundamental for having information about how this addiction is behaving, since the epidemic’s prevalence, i.e., the total number of addicts, is arrived at by adding the number of new users to the number of existing users (until they stop using). The total number of heroin addicts reached its peak at the beginning of the 1990s, with over 150,000 users in Spain.

The data about the incidence of heroin usage in Spain has been estimated from the database provided by the Spanish Drug Observatory, a health institution in possession of the anonymous records from people treated at Spanish public health centres and public foundations. Despite the study’s limitations, its authors maintain that, methodologically, these observations have acted as an indirect indicator of total heroin use in Spain.

To this effect, another conclusion drawn from this work is the suitability of the methodological approach employed from observable tendencies, which is being adapted to analyse the incidence of other addictions among the Spanish population, such as cocaine, from the beginning to the present day. Likewise, the researchers note that it must be studied whether the appearance of other substances may have changed usage habits and, accordingly, the incidence of usage of other addictive drugs, without losing sight of the possibility of heroin use seeing a resurge.

Reference article: “Problematic heroin use incidence trends in Spain”. Addiction, DOI:10.1111/j.1360-0443.2008.02451.x

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