Effects of rapid response systems on clinical outcomes: Systematic review and meta-analysis

BACKGROUND: A rapid response system (RRS) consists of providers who immediately assess and treat unstable hospitalized patients. Examples include medical emergency teams and rapid response teams. Early reports of major improvements in patient outcomes led to widespread utilization of RRSs, despite the negative results of a subsequent cluster-randomized trial. PURPOSE: To evaluate the effects of RRSs on clinical outcomes through a systematic literature review. DATA SOURCES: MEDLINE, BIOSIS, and CINAHL searches through August 2006, review of conference proceedings and article bibliographies. STUDY SELECTION: Randomized and nonrandomized controlled trials, interrupted time series, and before-after studies reporting effects of an RRS on inpatient mortality, cardiopulmonary arrests, or unscheduled ICU admissions. DATA EXTRACTION: Two authors independently determined study eligibility, abstracted data, and classified study quality. DATA SYNTHESIS: Thirteen studies met inclusion criteria: 1 cluster-randomized controlled trial (RCT), 1 interrupted time series, and 11 before-after studies. The RCT showed no effects on any clinical outcome. Before-after studies showed reductions in inpatient mortality (RR = 0.82, 95% CI: 0.74-0.91) and cardiac arrest (RR = 0.73, 95% CI: 0.65-0.83). However, these studies were of poor methodological quality, and control hospitals in the RCT reported reductions in mortality and cardiac arrest rates comparable to those in the before-after studies. CONCLUSIONS: Published studies of RRSs have not found consistent improvement in clinical outcomes and have been of poor methodological quality. The positive results of before-after trials likely reflects secular trends and biased outcome ascertainment, as the improved outcomes they reported were of similar magnitude to those of the control group in the RCT. The effectiveness of the RRS concept remains unproven.