Achieving universal health coverage of opioid agonist treatment in Norway: a cost-utility analysis

Background

Opioid use disorder (OUD) results in adverse health effects among patients and substantial societal cost. Detailed information on the healthcare and societal costs of OUD, as well as treatment with opioid agonist treatment (OAT) in Europe, especially in Norway, is sparse. This study aims to evaluate incremental costs and effects of scaling up and continuing the treatment of OUD with OAT in Norway through an equity-adjusted cost-utility analysis.

Methods

A two-state Markov model was constructed to evaluate the lifetime costs and outcomes of OAT as compared to no OAT among OUD patients. Various delivery platforms were assessed in the scale-up scenario, ranging from extended health-services in pharmacies, primary healthcare platforms, to tertiary care outpatient OAT clinics.  The analysis was conducted from Norwegian extended health-service and societal perspectives, with a 55-year time horizon. The mortality rate during OAT was calculated using primary data of patients (n= 22941) referred to specialized addiction care at Haukeland University Hospital, Norway between 2011 and 2020. All other parameters were extracted or calculated using open-access databases, published literature, the national OAT status report, financial records from the hospital, and consultations with patient representatives and experts from Bergen and Oslo. Health outcomes were measured in quality-adjusted-life-years (QALYs), and costs were presented in 2023 Norwegian Kroner (NOK). The analysis’s outcome was presented as incremental cost per QALY gained. The willingness-to-pay (WTP) threshold was estimated according to the severity criterion for priority setting in healthcare in Norway, using the absolute shortfall value calculated through the Markov model. Additionally, a budget impact analysis was conducted to estimate the total investment required to extend OAT to 100% of the prevalent cases. Uncertainty in the parameters was assessed with various sensitivity analyses.

Results

The loss of future QALYs among OUD patients (absolute shortfall) was estimated to be 22.11 QALYs. According to the severity criterion, for such a high absolute shortfall value, a WTP threshold of NOK 825,000 per QALY is accepted for allocation decisions in healthcare in Norway. The probabilistic sensitivity analysis estimated a mean incremental cost-effectiveness ratio of NOK 532,350 per QALY from the Norwegian extended health-service perspective, and highlighted that OAT was 80% likely to be cost-effective at the given WTP threshold. From a societal perspective, OAT was dominant (more effective and less costly) over no OAT. An investment of NOK 1.4 billion over the next 5 years was estimated to extend OAT to all OUD patients in Norway by the 5th year.

Conclusion

This study highlights OAT’s potential to reduce the economic burden in a society while improving patient’s health outcomes. Therefore, the study recommends that OAT should be considered for further scale-up to reach more patients with OUD.