Out-of-hospital cardiac arrest: A systematic review of current risk scores to predict survival

Importance: The arrest and the post-arrest period are an incredibly emotionally traumatic time for family and friends of the affected individual. There is a need to assess prognosis early in the patient pathway to offer objective, realistic and non-emotive information to the next-of-kin regarding the likelihood of survival.

Objective: To present a systematic review of the clinical risk scores available to assess patients on admission following out-of-hospital cardiac arrest (OHCA) which can predict in-hospital mortality.

Evidence review: A systematic search of online databases Embase, MEDLINE and Cochrane Central Register of Controlled Trials was conducted up until 20th November 2020.

Findings: Out of 1,817 initial articles, we identified a total of 28 scoring systems, with 11 of the scores predicting mortality following OHCA included in this review. The majority of the scores included arrest characteristics (initial rhythm and time to return of spontaneous circulation) as prognostic indicators. Out of these, the 3 most clinically-useful scores, namely those which are easy-to-use, comprise of commonly available parameters and measurements, and which have high predictive value are the OHCA, NULL-PLEASE, and rCAST scores, which appear to perform similarly. Of these, the NULL-PLEASE score is the easiest to calculate and has also been externally validated.

Conclusions: Clinicians should be aware of these risk scores, which can be used to provide objective, nonemotive and reproducible information to the next-of-kin on the likely prognosis following OHCA. However, in isolation, these scores should not form the basis for clinical decision-making.