Reduction in hospital mortality over time in a hospital without a pediatric medical emergency team: limitations of before-and-after study designs.

OBJECTIVE: To determine whether hospital mortality has decreased over time in a hospital that has not introduced a pediatric medical emergency team (PMET).
DESIGN: Retrospective observational study.
SETTING: Quaternary children's hospital. PARTICIPANTS: All pediatric inpatient separations (defined as any discharge, including death) during 10 fiscal years. MAIN OUTCOME MEASURES: We searched our hospital administrative database to determine the number of pediatric inpatient separations and deaths, and we searched the hospital switchboard and pediatric intensive care databases to determine ward code and cardiopulmonary arrest rates. Relative risks (RRs) with 95% confidence intervals (CIs) and logistic regression compared results over time.
RESULTS: During the periods of the 2 PMET studies showing a reduction in hospital mortality, we found a decrease in hospital mortality: for 1999-2002 vs 2002-2006, 212 deaths among 14 161 patients (1.50%) vs 219 of 26 767 (0.82%), RR, 0.55 (95% CI, 0.44-0.69); for 2000-2005 vs 2005-2007, 300 deaths among 29 497 patients (1.02%) vs 98 of 14 005 (0.70%), RR, 0.69 (95% CI, 0.55-0.86). During the periods of the 3 PMET studies showing no change in or not examining hospital mortality, we found no significant change in hospital mortality. The annual odds ratio for survival was 1.13 (95% CI, 1.09-1.16). There were no changes in ward code and cardiopulmonary arrest rates over time.
CONCLUSIONS: We found a reduction in hospital mortality over time in a children's hospital without a PMET. This demonstrates the limitation of before-and-after study designs, and we hypothesize that multiple co-interventions account for the decrease in mortality. Whether a PMET could have reduced mortality further is unknown.