Assessing AIDS prevention for injecting drug users; some methodological considerations

There is an urgent need to develop strategies aimed at reducing the spread of HIV infection amongst injecting drug users. It is essential that any such initiatives are monitored and evaluated. It is the contention of this paper that evaluation should be rigorous, flexible and comparative. To achieve this we need to examine the basic principles of evaluation, both in terms of service delivery and process evaluation, as well as outcome measures. In the evaluation task it is important to distinguish clearly and unequivocally between implementation and impact, aims and objectives. At the practical level, researchers need to give due consideration to liaison with agency staff. Methodologically, issues such as demonstrating impact and rival explanations must be addressed. The paper concludes by proposing and illustrating a model for evaluation that has particular relevance to community-base initiatives aimed at reducing the spread of HIV infection.