Take-home naloxone to prevent fatalities from opiate-overdose: Protocol for Scotland's public health policy evaluation, and a new measure to assess impact

Aims: Scotland was the first country to adopt take-home naloxone (THN) as a funded public health policy. We summarise the background and rigorous set-up for before/after monitoring to assess the impact on high-risk opiate-fatalities. Methods: Evidence-synthesis of prospectively monitored small-scale THN schemes led to a performance indicator for distribution of THN-kits relative to opiate-related deaths. Next, we explain the primary outcome and statistical power for Scotland's before/after monitoring. Results: Fatality-rate at opiate overdoses witnessed by THN-trainees was 6% (9/153, 95% CI: 2-11%). National THN-schemes should aim to issue 20 times as many THN-kits as there are opiate-related deaths per annum; and at least nine times as many. Primary outcome for evaluating Scotland's THN policy is reduction in the percentage of all opiate-related deaths with prison-release as a 4-week antecedent. Scotland's baseline period is 2006-10, giving a denominator of 1970 opiate-related deaths. A priori plausible effectiveness was 20-30% reduction, relative to baseline, in the proportion of opiate-related deaths that had prison-release as a 4-week antecedent. A secondary outcome was also defined. Conclusion: If Scotland's THN evaluation shifts the policy ground seismically, our new performance measure may prove useful on how many THN-kits nations should provide annually.