Cost-effectiveness analysis of Canada's National Overdose Response Service

We evaluate the cost-effectiveness of Canada's National Overdose Response Service (NORS) and in particular, highlight the conditions under which the cost-effectiveness decision would change, given the uncertainty in estimating the overall risk of fatal and non-fatal overdose in comparison to overall programme costs.

We conducted a retrospective cost-effectiveness analysis using a Markov cohort model from a health sector perspective, incorporating health states related to substance use, overdose and mortality. Model parameters were calibrated using Canadian overdose data, and probabilistic sensitivity analyses were performed to assess cost-effectiveness.

Our study evaluated Canada's NORS, an overdose response hotline, and reflected community-based substance use settings where overdoses may occur without supervision.

Primary outcomes measured in quality-adjusted life-years (QALYs) and incremental cost-effectiveness ratios (ICERs) at a willingness-to-pay threshold of $C100 000 per QALY.

Our model calibration accurately fit fatal overdose targets from 2020 to 2023 and included a total of 9402 calls and 148 overdose events over the study period. We estimated an 11% baseline risk of death for unwitnessed overdoses and a 78% probability of a witnessed overdose. Over a lifetime, NORS was the dominant strategy, yielding 0.46 additional QALYs (95% credible interval (CrI) 0.13 to 1.15) and cost savings of $C25 405 (CrI -$C123 618 to $C24 351). While not cost-effective in the first year (ICER=$C725 843/QALY), NORS became cost-effective beyond 5 years at a $C100 000/QALY threshold. Sensitivity analyses highlighted the cost per NORS call and EMS call-out probability as key cost drivers, while NORS coverage and overdose risk influenced QALYs. NORS remained cost-effective under a broad range of risk and cost scenarios.

The NORS intervention is a cost-effective and cost-saving strategy for reducing fatal overdose risk over a lifetime, offering substantial population-level health benefits and a critical opportunity to mitigate overdose fatalities amid shifting harm reduction policies and threatened supervised consumption site closures.