Overcoming the barriers experienced in conducting a medication trial in adults with aggressive challenging behaviour and intellectual disabilities.

Background Aggressive challenging behaviour in people with intellectual disability (ID) is frequently treated with antipsychotic drugs, despite a limited evidence base. Method A multi-centre randomised controlled trial was undertaken to investigate the efficacy, adverse effects and costs of two commonly prescribed antipsychotic drugs (risperidone and haloperidol) and placebo. Results The trial faced significant problems in recruitment. The intent was to recruit 120 patients over 2 years in three centres and to use a validated aggression scale (Modified Overt Aggression Scale) score as the primary outcome. Despite doubling the period of recruitment, only 86 patients were ultimately recruited. Conclusions Variation in beliefs over the efficacy of drug treatment, difficulties within multidisciplinary teams and perceived ethical concerns over medication trials in this population all contributed to poor recruitment. Where appropriate to the research question cluster randomised trials represent an ethically and logistically feasible alternative to individually randomised trials.