Abstract P182: The Effect of Case Volume on Cardiopulmonary Resuscitation Outcome of Out-of-hospital Cardiac Arrest; An Observational Study and Propensity Score Matching Analysis
Background Case volume has been known to be a key quality indicator in health care system. The purpose is to investigate the effect of high case volume on the outcome of out-of-hospital cardiac arrest (OHCA).
Methods We used a nationwide OHCA cohort (2006 –2007) from retrospective medical record review using ambulance run sheet of Korea which has a single-tiered basic life support ambulance service. We included OHCA patients transported to designated regional and local EDs and excluded cases unable to know hospital outcome. EDs were divided into two groups- high volume (HV) and low volume (LV) group - by their case volumes of CPR. The cut-off value was the median value for model 1 and 75 percentile value for model 2. A matching process based on propensity score was done to equalize potential prognostic factors in both groups, and formulated a balanced 1:1 matched cohort study. The primary and secondary endpoint was survival to admission and survival to discharge from hospital, respectively. Adjusted odds ratio (OR)(95% confidence interval) was calculated from multivariates logistic regression model. The goodness-of-fit was tested by Hosmer-Lemeshow (HL) chi-square.
Results Of the 34,552 patients with OHCA treated, 15,458 (45.7%) from 121 EDs were included. Survival to admission and to discharge was 14.0% and 4.5%, respectively. Median and 75 percentile number in case volume between HV and LV EDs was 120 (model 1) and 158 (model 2), respectively. From propensity score matching, each 4,005 cases (model 1) and 1,614 (model 2) were assigned to both arms. Demographic findings in gender, age, response interval, call to ED arrival time, witness, bystander CPR, prehospital defibrillation, pre-hospital EMS CPR, cause, and ECG were similar in both arms of each models (all p-values >0.05). Adjusted OR for survival to admission in HV versus LV group was 1.09 (0.96 –1.24) in model 1 and 1.34 (1.10 –1,63) in model 2. Adjusted OR for survival to discharge was 1.52 (1.24 –1.87) with HL chi-square (8.1, p=0.43) in model 1 and 1.45 (1.07–1.95) with HL chi-square (5.1, p=0.75) in model 2.
Conclusion ED with high volume of CPR cases showed significantly better performance for survival to discharge, which may be considered as an evidence of regionalized specialty care system for OHCA.