of Study 4 Opiates and Criminal Behaviour -a review of the literature 6 Criminal Behaviour in Treatment-seeking Opiate Addicts 34 Crime and Opioid Dependence: changes after entering a methadone treatment programme 59 Economic Evaluation: Does methadone treatment lead to reduced expenditures on illegal drugs and a fall in criminal earnings? 84 References 105substantially related to obtaining money for their drugs -the more crimes that they committed the more drugs they could purchase. The rate of their criminal activity was influenced, however, by previous involvement in crime, especially acquisitive offending. The criminal activities of the sample also appeared to be independently driven by both the cost of their drug habit and their previous history and experience of acquisitive crime. Overall use of heroin decreased by 50%. There was a significant reduction in expenditure on drugs, injecting behaviour, and high-risk behaviours involving sharing of syringes and needles. Expenditure showed a threefold reduction. However, there were no changes in a range of other illicit drugs misused. But there were no increases in the use of other drugs and subjects had not substituted these for heroin. There was a significant increase in legally obtained income during the treatment phase, certain subjects having found work.Burglaries and theft were reduced by a half and the impact on drug-dealing was even greater.However, there were no changes in the level of fraudulent activities, muggings, sex work, or signing on for Department of Social Security Benefits whilst simultaneously working.Treatment appeared to have had its greatest impact on those individuals who were most heavily involved in crime. This important finding did not suggest that methadone treatment is most effective with subjects who are thought to be "easy" to treat and not engaged in crime.Retention in the treatment programme was confirmed as a highly important factor, strongly and independently associated with both reduction in illicit use of opiates and reduction in criminal activities.
Economic EvaluationAn economic evaluation was carried out on the effectiveness of methadone treatment on the sample of 81 subjects. Subjects who remained on methadone treatment for longer periods were found to have better outcomes over the six month follow-up period. If an opiate addict were to be maintained in methadone treatment for six months, statistical modelling predicted that expenditure on street drugs would fall by £35 per day on average over the period of the study. Based on the 95% confidence intervals from the regression equations, this would lead to an average fall in monthly criminal earnings of between £714 and £2,626 over the six months study period. The results support the view that, in the short-term, methadone treatment may be a viable policy tool for intervening in drug use and drugrelated crime.