To investigate the occurrence of response in the course of the experimental phase of the trial, the percentage responders in the intention-to-treat population was calculated for each assessment-point, using LOCF for each missing assessment during the trial. The results are displayed in Figure 12.

Two months after baseline, at the first assessment-point, response occurred in 43.4% of the participants in the heroin group, compared to 18.4% in the methadone group. In the heroin group, response remained stable in the following four months, and subsequently gradually increased from 43.4% at month 6 to 46.1% at month 8, 48.7% at month 10, and to 56.6% at the endpoint at month 12.

Figure 12. Percentage responders at subsequent assessments

In the methadone group, on the other hand, following the initial 18.4% response at month 2, and a subsequent increase to 26.5% at month 4, the response rate remained largely unchanged during the subsequent eight months of the trial, amounting to 31.6% at month 12.