Blattler et al (2002)

Aim To investigate whether supplying heroin on a medical programme, combined with therapy, would reduce cocaine use among participants, and to investigate what factors were linked to cocaine use in multiple-drug users.

Procedure Participants 266 (addicts on a drug treatment programme in Switzerland) 97 Female and 168 Male. All had previously attempted twice before to give up the addiction. Mean age of 30. On average participants had been using heroin for 10 years and cocaine for 7 years. All participants gave informed consent. All participants lived and worked in their normal environment.

Procedure Attendance for counselling was compulsory. Participants were interviewed at the start and then at 6-monthly intervals during the study period of 18 months. Drug usage was monitored by unannounced urine tests. The results was used to monitor which drugs were being taken - as self reports can be inaccurate. Dosages, time and method of administration for both heroin and any other medications were recorded.

Results By the end of the study, the number of cocaine users taking cocaine on a daily basis had dropped by more than 80%. Of the 261 individuals for whom the researchers had complete data, 99 had the same pattern of cocaine use at the end of the study as at the start. 15 participants had increased the amount of cocaine they used. 147 had reduced the amount of cocaine they used. At the start of the programme 84 of the participants stated they had worked in the commercial sex trade, by the end only 7 stated they was still working in the industry.

Conclusion The high correlation between self-reported data and the urine samples suggests self-report data is good but not 100% reliable. This relationship became stronger as the study progressed. Cocaine maintained a steady price - meaning there must have been other reasons for the drop in use. Although the results are good for those who are heavy drug users, this study does not represent the wider population.