Author Affiliations: Division of Pediatric Intensive Care, Department of Pediatrics, University of Alberta, and Stollery Children's Hospital, Edmonton (Drs Joffe and Anton), and Division of Pediatric Intensive Care, Department of Pediatrics, University of Calgary, and Alberta Children's Hospital, Calgary (Dr Burkholder), Alberta, Canada.
We thank Sharek et al for their comments. We disagree with the conclusion that their study design was sufficient to show efficacy of pediatric medical emergency team (PMET) implementation.
First, the statistical technique of ARIMA time-series analysis is superior to simple before-and-after comparisons, as it can model the effects of random error over time. We do not believe that ARIMA can “eliminate the biases of a simple before-and-after design,” completely account for unmeasured confounding factors that are temporally coincident (or even temporally related by delayed effects) to the intervention, nor solve the problem of systematic bias noted in studies involving historical controls.1- 3 With only 19 postimplementation event rates in their ARIMA model,4 there is risk of type I error.1 A recent publication graphs 8 additional postimplementation event rates: hospital mortality increased again, and the ARIMA model parameter estimate for PMET intervention was no longer visually or statistically significant (Figure 1 and Table 3).5 Moreover, the hospital had several quality interventions (infection and adverse drug event reduction strategies and creation of a hospitalist program) implemented over the period of the PMET study that may be confounders.5 Of note, ARIMA was not used for analysis of ward code rates.4 More than 40% of deaths were in “newborns and other neonates with conditions originating in the perinatal period”; improvements may have been driven by perinatal care and less by care in the general pediatric population.4
Joffe AR, Anton NR, Burkholder SC. Rapid Response Team Implementation in a Children’s Hospital—Reply. Arch Pediatr Adolesc Med. 2011;165(12):1139-1140. doi:10.1001/archpedi.165.12.1139-b