The total costs were $10,621,305,000 for the status quo, $10,661,414,000 for high methadone substitution, and $10,778,843,000 for high methadone substitution plus high ART.
The total QALYs gained were 32,749,000 for the status quo, 32,825,000 for high methadone substitution, and 32,930,000 for high methadone substitution plus high ART.
All the other interventions were dominated as they were less effective and more costly or less cost-effective than one of these three interventions.
Compared with the status quo, high methadone substitution was associated with an incremental cost-utility ratio of $530 per QALY gained. Compared with high methadone substitution, high methadone substitution plus ART was associated with an incremental cost-utility ratio of $1,120 per QALY gained.
The results were most sensitive to changes in risky sexual and injecting behaviours, the effectiveness of methadone, ART effectiveness, and the infectivity of unsafe sexual practices and equipment sharing. The probabilistic sensitivity analysis produced mean values that matched the results of the base case.