Adrenaline to improve survival in out-of-hospital cardiac arrest: the PARAMEDIC2 RCT.

Abstract

Background: Adrenaline has been used as a treatment for cardiac arrest for many years, despite uncertainty about its effects on long-term outcomes and concerns that it may cause worse neurological outcomes.

Objectives: The objectives were to evaluate the effects of adrenaline on survival and neurological outcomes, and to assess the cost-effectiveness of adrenaline use.

Design: This was a pragmatic, randomised, allocation-concealed, placebo-controlled, parallel-group superiority trial and economic evaluation. Costs are expressed in Great British pounds and reported in 2016/17 prices.

Setting: This trial was set in five NHS ambulance services in England and Wales.

Participants: Adults treated for an out-of-hospital cardiac arrest were included. Patients were ineligible if they were pregnant, if they were aged < 16 years, if the cardiac arrest had been caused by anaphylaxis or life-threatening asthma, or if adrenaline had already been given.

Interventions: Participants were randomised to either adrenaline (1 mg) or placebo in a 1 : 1 allocation ratio by the opening of allocation-concealed treatment packs.

Main outcome measures: The primary outcome was survival to 30 days. The secondary outcomes were survival to hospital admission, survival to hospital discharge, survival at 3, 6 and 12 months, neurological outcomes and health-related quality of life through to 6 months. The economic evaluation assessed the incremental cost per quality-adjusted life-year gained from the perspective of the NHS and Personal Social Services. Participants, clinical teams and those assessing patient outcomes were masked to the treatment allocation.

Results: From December 2014 to October 2017, 8014 participants were assigned to the adrenaline (n = 4015) or to the placebo (n = 3999) arm. At 30 days, 130 out of 4012 participants (3.2%) in the adrenaline arm and 94 out of 3995 (2.4%) in the placebo arm were alive (adjusted odds ratio for survival 1.47, 95% confidence interval 1.09 to 1.97). For secondary outcomes, survival to hospital admission was higher for those receiving adrenaline than for those receiving placebo (23.6% vs. 8.0%; adjusted odds ratio 3.83, 95% confidence interval 3.30 to 4.43). The rate of favourable neurological outcome at hospital discharge was not significantly different between the arms (2.2% vs. 1.9%; adjusted odds ratio 1.19, 95% confidence interval 0.85 to 1.68). The pattern of improved survival but no significant improvement in neurological outcomes continued through to 6 months. By 12 months, survival in the adrenaline arm was 2.7%, compared with 2.0% in the placebo arm (adjusted odds ratio 1.38, 95% confidence interval 1.00 to 1.92). An adjusted subgroup analysis did not identify significant interactions. The incremental cost-effectiveness ratio for adrenaline was estimated at £1,693,003 per quality-adjusted life-year gained over the first 6 months after the cardiac arrest event and £81,070 per quality-adjusted life-year gained over the lifetime of survivors. Additional economic analyses estimated incremental cost-effectiveness ratios for adrenaline at £982,880 per percentage point increase in overall survival and £377,232 per percentage point increase in neurological outcomes over the first 6 months after the cardiac arrest.

Limitations: The estimate for survival with a favourable neurological outcome is imprecise because of the small numbers of patients surviving with a good outcome.

Conclusions: Adrenaline improved long-term survival, but there was no evidence that it significantly improved neurological outcomes. The incremental cost-effectiveness ratio per quality-adjusted life-year exceeds the threshold of £20,000-30,000 per quality-adjusted life-year usually supported by the NHS.

Future work: Further research is required to better understand patients' preferences in relation to survival and neurological outcomes after out-of-hospital cardiac arrest and to aid interpretation of the trial findings from a patient and public perspective.

Trial registration: Current Controlled Trials ISRCTN73485024 and EudraCT 2014-000792-11.

Funding: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 25. See the NIHR Journals Library website for further project information.