Rapid response teams are being widely implemented in hospitals worldwide. These teams are summoned to evaluate patients who meet specific clinical "triggers" (e.g., abnormal vital signs). This systematic review evaluated the ability of such triggers to accurately identify inpatients whose clinical condition is deteriorating. The false-negative rate of commonly used triggers was relatively high, meaning that a significant proportion of acutely unstable patients would not be identified by such criteria. This problem was noted in a prior negative study of rapid response teams. The authors recommend further research to determine the combination of triggers that most accurately identifies clinical instability.