External validation of the ROSC after cardiac arrest (RACA) score in a physician staffed emergency medical service system

Abstract

BackgroundThe return of spontaneous circulation (ROSC) after cardiac arrest (RACA) score may have implications as a quality indicator for the emergency medical services (EMS) system. We aimed to validate this score externally in a physician staffed urban EMS system.MethodsWe conducted a retrospective cohort study. Data on resuscitation attempts from the Helsinki EMS cardiac arrest registry from 1.1.2008 to 31.12.2010 were collected and analyzed. For each attempted resuscitation the RACA score variables were collected and the score calculated. The endpoint was ROSC defined as palpable pulse over 30 s. Calibration was assessed by comparing predicted and observed ROSC rates in the whole sample, separately for shockable and non-shockable rhythm, and separately for resuscitations lead by a specialist, registrar or medical supervisor (i.e., senior paramedic). Data are presented as medians and interquartile ranges. Statistical testing included chi-square test, the Mann-Whitney U test, Hosmer-Lemeshow goodness of fit test and calculation of 95% confidence intervals (CI) for proportions.ResultsA total of 680 patients were included of whom 340 attained ROSC. The RACA score was higher in patients with ROSC (0.62 [0.46–0.69] than in those without (0.46 [0.36–0.57]) (p < 0.001). Observed against predicted ROSC indicated reasonable calibration overall (p = 0.30), with better calibration in patients with a shockable initial rhythm (p = 0.75) than in patients with a non-shockable rhythm (p = 0.04). There was no statistical difference between observed and predicted ROSC rates in resuscitations attended by a specialist (50% vs 53%, 95% CI 45–55) or registrar (55% vs 53%, 95% CI 48–62), but rates were lower than predicted in resuscitations lead by a medical supervisor (36% vs 49%, 95% CI 25–47).DiscussionDeveloping a practical severity-of-illness scoring system for out-of-hospital cardiac arrest patients would allow patient heterogeneity adjustment and measurement of quality of care in analogy to commoly used severity-of-illness- scores developed for the similar purposes for the general intensive care unit population. However, transferring RACA score to another country with different population and EMS system might affect the performance and generalizability of the score.ConclusionsThis study found a good overall calibration and moderate discrimination of the RACA score in a physician staffed urban EMS system which suggests external validity of the score. Calibration was suboptimal in patients with a non-shockable rhythm which may due to a local do-not-attempt-resuscitation policy. The lower than expected overall ROSC rate in resuscitations attended by medical supervisors requires further study.

Polish Helicopter Emergency Medical Service (HEMS) Response to Out-of-Hospital Cardiac Arrest (OHCA): A Retrospective Study

“…The present analysis also shows that in women and in patients younger than 40, resuscitation was successful and ROSC was achieved significantly more often. The present findings are also consistent with those reported by Kupari et al (2017), Krishna et al (2017), Requena-Morales et al (2017), and Fan et al (2017) in studies on OHCA [ 1 , 11 – 13 ].…”

“…Out-of-hospital cardiac arrest (OHCA) is the most common cause of mortality and severe neurological deficits among patients in Europe. Annually, OHCA occurs in 275 000 patients, which is in line with the incidence of 38–55 cases per 100 000 annually for which emergency medical teams performed cardiopulmonary resuscitation (CPR) [ 1 – 3 ]. The survival rate in OHCA ranges from 5% to 38% and is associated with differences in pre-hospital management [ 4 ].…”

Mobile phone-based alerting of CPR-trained volunteers simultaneously with the ambulance can reduce the resuscitation-free interval and improve outcome after out-of-hospital cardiac arrest: A German, population-based cohort study

“…Contrarily, where the observed ROSC rate is lower than the predicted ROSC rate, further analyses of the EMS-structure and process quality may be useful to identify reasons for that low performance. 22 In our study, we saw a striking difference in patients who underwent Mobile-Rescuer-initiated-CPR. The predicted ROSC rate in this group was about 30%, as low as in patients who underwent EMS-initiated-CPR, yet the observed ROSC rate, and particularly the ROSC rate at hospital admission, was 45%the highest of all study groups.…”

“…13 This is considered a simple tool enabling comparison between predicted and observed ROSC rates, based on readily-available variables after OHCA. 22 The RACA score may contribute to preclinical quality assessment and help analyse the effects of different therapeutic strategies. 13,22,23 In EMS teams operating at a high-quality level, the observed ROSC rate may be higher than the predicted ROSC rate.…”

“…22 The RACA score may contribute to preclinical quality assessment and help analyse the effects of different therapeutic strategies. 13,22,23 In EMS teams operating at a high-quality level, the observed ROSC rate may be higher than the predicted ROSC rate. Contrarily, where the observed ROSC rate is lower than the predicted ROSC rate, further analyses of the EMS-structure and process quality may be useful to identify reasons for that low performance.…”