The cost-effectiveness of mild hypercapnia after out-of-hospital cardiac arrest: a health economic evaluation alongside the TAME study

Background: Out of hospital cardiac arrest (OHCA) is a significant public health problem associated with high mortality and high healthcare costs. The Targeted Therapeutic Mild Hypercapnia after Resuscitated Cardiac Arrest (TAME) randomised clinical trial showed that targeted mild hypercapnia did not lead to better neurologic outcomes at 6 months compared to normocapnia after OHCA. We aimed to estimate the cost-effectiveness of mild hypercapnia compared to targeted normocapnia using data from the TAME trial. Methods: Pre-specified, prospective cost-effectiveness analysis alongside the TAME RCT from a healthcare perspective using a 6-month time horizon. The analysis included 1586 patients across 63 intensive care units (ICUs), in 17 countries. The primary measure of cost-effectiveness was the cost per quality-adjusted life year (QALY). Costs were estimated for each patient by multiplying resource use data by the relevant country-specific resource unit cost. QALYs were calculated using utility scores derived from the EQ-5D-5L administered at 6-month follow-up. Findings: There were no significant differences in costs or QALYs at 6 months between groups. The incremental net monetary benefit was also not significant at a willingness-to-pay threshold of $50,000 per QALY, with the 95 % CI including both negative and positive values. Interpretation: This analysis found that the cost-effectiveness of mild hypercapnia is highly uncertain when compared with normocapnia in adult patients following OHCA, with no significant differences in either costs or outcomes. Further research is required to determine the specific circumstances under which mild hypercapnia may provide value for money.