Objectives: To understand the changes in the population incidence of inhospital cardiopulmonary arrest (IHCA) and mortality associated with the introduction of rapid response systems (RRSs).
Design, setting and participants: Population-based study of 9 221 138 hospital admissions in 82 public acute hospitals in New South Wales, using data linked to a death registry, from 1 Jan 2002 to 31 Dec 2009.
Main outcome measures: Changes in IHCA, IHCA-related mortality, hospital mortality and proportion of IHCA patients surviving to hospital discharge.
Results: RRS uptake increased from 32% in 2002 to 74% in 2009. This increase was associated with a 52% decrease in IHCA rate, a 55% decrease in IHCA-related mortality rate, a 23% decrease in hospital mortality rate and a 15% increase in survival to discharge after an IHCA (all P < 0.01). The adjusted absolute reductions in IHCA-related mortality and hospital mortality were 1.49 (95% CI, 1.30-1.68) and 4.05 (95% CI, 3.17-4.76) patients per 1000 admissions, respectively. The decrease in IHCA incidence rate accounted for 95% of the reduction in IHCA-related mortality. In contrast, the increase in IHCA survival accounted for only 5% of the reduction in IHCA-related mortality.
Conclusions: During nearly a decade, as RRSs were progressively introduced, there was a coincidental reduction in IHCA, IHCA-related deaths and hospital mortality and an increased survival to hospital discharge after an IHCA. Reduced IHCA incidence, rather than improved postcardiac arrest survival, was the main contributor to the reduction in IHCA mortality.