As has been outlined in paragraph 2.2.1, the study subjects were randomized to one of two (injectable heroin trial) or three (inhalable heroin trial) treatment conditions. The conditions and primary assessment-points in the study are schematically displayed in Figure 3.

Figure 4. Treatment conditions and primary assessment-points

The primary analysis of the effectiveness of treatment with heroin and/or methadone during 12 months was conducted on the comparison between the assessment on day 1 of phase III in group A (assessment [4]) and that in group B (assessment [10]), with as baseline the assessment on day 1 of phase IIa (assessment [2] and [8], respectively).