Rapid response systems: A systematic review*

CONTEXT: Rapid response systems have been advocated as a potential model to identify and intervene in patients who are experiencing deterioration on general hospital wards. OBJECTIVE: To conduct a meta-analysis to evaluate the impact of rapid response systems on hospital mortality and cardiac arrest rates. DATA SOURCE: We searched MEDLINE, EMBASE, and the Cochrane Library from January 1, 1990, to June 30, 2005, for all studies relevant to rapid response systems. We restricted the search to the English language and by age category (all adults: >or=19 years). STUDY SELECTION: We selected observational and randomized trials of rapid response systems that provided empirical data on hospital mortality and cardiac arrest in control and intervention groups. We reviewed 10,228 abstracts and identified eight relevant studies meeting these criteria. DATA SYNTHESIS: Of the included studies, five used historical controls, one used concurrent controls, and two used a cluster-randomized design. The pooled relative risk for hospital mortality comparing rapid response teams to control was 0.76 (95% confidence interval, 0.39-1.48) between the two randomized studies and 0.87 (95% confidence interval, 0.73-1.04) among the five observational studies. The pooled relative risk for cardiac arrest comparing rapid response systems to control was 0.94 (95% confidence interval, 0.79-1.13) in the single randomized study and 0.70 (95% confidence interval, 0.56-0.92) in four observational studies. CONCLUSIONS: We found weak evidence that rapid response systems are associated with a reduction in hospital mortality and cardiac arrest rates, but limitations in the quality of the original studies, the wide confidence intervals, and the presence of heterogeneity limited our ability to conclude that rapid response systems are effective interventions. Large randomized controlled trials are needed to clarify the efficacy of rapid response systems before they should become standard of care.