Mild therapeutic hypothermia after cardiac arrest - effect on survival with good neurological outcome outside of randomised controlled trials A registry-based analysis

BACKGROUND For nearly 20 years, in international guidelines, mild therapeutic hypothermia (MTH) was an important component of postresuscitation care. However, recent randomised controlled trials have questioned its benefits. At present, international guidelines only recommend actively preventing fever, but there are ongoing discussions about whether the majority of cardiac arrest patients could benefit from MTH treatment. OBJECTIVE The aim of this study was to compare the outcome of adult patients treated with and without MTH after cardiac arrest. DESIGN Observational cohort study. SETTING German Resuscitation Registry covering more than 31 million inhabitants of Germany and Austria. PATIENTS All adult patients between 2006 and 2022 with out-of-hospital or in-hospital cardiac arrest and comatose on admission. MAIN OUTCOME MEASURES Primary endpoint: hospital discharge with good neurological outcome [cerebral performance categories (CPC) 1 or 2]. Secondary endpoint: hospital discharge. We used a multivariate binary logistic regression analysis to identify the effects on outcome of all known influencing variables. RESULTSWe analysed 33 933 patients (10 034 treated with MTH, 23 899 without MTH). The multivariate regression model revealed that MTH was an independent predictor of CPC 1/2 survival and of hospital discharge with odds ratio (95% confidence intervals) of 1.60 (1.49 to 1.72), P < 0.001 and 1.89 (1.76 to 2.02), P < 0.001, respectively. CONCLUSION Our data indicate the existence of a positive association between MTH and a favourable neurological outcome after cardiac arrest. It therefore seems premature to refrain from giving MTH treatment for the entire spectrum of patients after cardiac arrest. Further prospective studies are needed.