Eight studies were included: two cluster RCTs (n=127,925 patients, range 2,795 to 125,132) and six observational studies (n=approximately 430,000 patients, range 2,183 to 199,024 patients). Five studies used historical controls. No study included a control group that the reviewers considered clearly comparable to the intervention group; four studies attempted to adjust for differences between groups statistically.
A statistically significant difference in hospital cardiac arrest rate (RR 0.70, 95% CI 0.56 to 0.92) was reported in favour of rapid response systems, based on observational studies (n=five studies). There was no statistically significant difference between rapid response systems and controls in a single RCT (RR 0.94, 95% CI 0.79 to 1.13). There was no statistically significant benefit in hospital mortality with rapid response systems in pooled results from the observational studies (RR 0.87, 95% CI 0.73 to 1.04; five studies) or the RCTs (RR 0.76, 95% CI 0.39 to 1.48; two studies).
In all analyses, Χ2 tests indicated statistically significant heterogeneity.