Association between Hospital volume of cardiopulmonary resuscitation for in-hospital cardiac arrest and survival to Hospital discharge

BACKGROUND Prior studies have shown that hospital case volume is not associated with survival in patients with out-of-hospital cardiac arrest (OHCA). However, how case volume impact on survival for in-hospital cardiac arrest (IHCA) is unknown. METHODS We queried the National Inpatient Sample (NIS) in the U.S. 2005-2011 to identify cases in which in-hospital CPR was performed for IHCA. Restricted cubic spine was used to evaluate the association between hospital annual CPR volume and survival to hospital discharge. RESULTS Across more than 1000 hospitals in NIS, we identified 125,082 cases (mean age 67, 45% female) of IHCA for which CPR was performed over the study period. Median [Q1, Q3] case volume was 60 [34, 99]. Compared to those in the 1 st quartile of case volume, hospitals in the 4th quartile tends to have younger patients (mean = 66 vs 68 yrs), higher comorbidities (median Elixhauser score = 4 vs 3), and in low income areas (37 vs 30%). Overall, 23% of the patients survived to hospital discharge. There was a non-linear association between CPR volume and survival: a non-significant trend towards better survival was observed with increasing annual CPR volume that reached a plateau at 51-55 cases per year, after which survival began to drop and became significantly lower after 75 cases per year (p for non-linearity