To maximize the comparability of the treatment conditions, the patients in the heroin condition had the same offer - in terms of type and amount - of additional psychosocial care available as patients in the control condition. This treatment offer was comparable to that in a regular methadone program ("treatment as usual"). All patients were medically screened and monitored, and could use the services of a social worker and existing social recovery programs if they wanted to. To investigate if extra places had to be created for additional treatment - if patients in the heroin condition would express an increased need for social care during the course of their heroin treatment - a pilot study was conducted prior to the start of the trials (Van der Lelij and Driessen, 1998). The pilot study indicated, that the amount and diversity of additional psychosocial treatment places was sufficient in all participating treatment programs to handle a possible increase in treatment need, so that waiting lists were not to be expected.
On individual indication and determined by the treating physician, each subject was permitted to receive co-prescribed medications and/or therapies for concurrent medical conditions. Where possible, the physician ensured that the prescribed concurrent medication did not interact negatively with the prescribed methadone or heroin. In addition, as some medications interact pharmacologically with methadone and/or heroin (e.g. medications against HIV or TBC), the physician could adjust the dose level of the prescribed methadone and heroin, if necessary. As with psychosocial counseling or therapy, all medical interventions and therapeutic prescriptions, including dose levels, reason for administration and outcome, were closely monitored during the two-monthly assessments and recorded in the CRF.