Cardiopulmonary arrest and mortality trends, and their association with rapid response system expansion

To the Editor: Chen and colleagues associate the reduction in inhospital cardiopulmonary arrest (IHCA) incidence with the introduction of rapid response systems.1 Their population-based study of all patients aged ≥ 14 years in New South Wales found that hospital mortality decreased between 2002 and 2009. During this period, the age of the hospital population increased and patients aged ≥ 75 years were more likely to die in hospital (risk ratio [RR], 28.4), have an IHCA (RR, 8.6), die as a result of cardiac arrest (RR, 11.9), or die within 12 months of discharge (RR, 5.3).1