Development and validation of a risk-adjustment tool in acute asthma

Abstract

Objective: To develop and prospectively validate a risk-adjustment tool in acute asthma.

Data sources: Data were obtained from two large studies on acute asthma, the Multicenter Airway Research Collaboration (MARC) and the National Emergency Department Safety Study (NEDSS) cohorts. Both studies involved >60 emergency departments (EDs) and were performed during 1996-2001 and 2003-2006, respectively. Both included patients aged 18-54 years presenting to the ED with acute asthma.

Study design: Retrospective cohort studies.

Data collection: Clinical information was obtained from medical record review. The risk index was derived in the MARC cohort and then was prospectively validated in the NEDSS cohort.

Principle findings: There were 3,515 patients in the derivation cohort and 3,986 in the validation cohort. The risk index included nine variables (age, sex, current smoker, ever admitted for asthma, ever intubated for asthma, duration of symptoms, respiratory rate, peak expiratory flow, and number of beta-agonist treatments) and showed satisfactory discrimination (area under the receiver operating characteristic curve, 0.75) and calibration ( p=.30 for Hosmer-Lemeshow test) when applied to the validation cohort.

Conclusions: We developed and validated a novel risk-adjustment tool in acute asthma. This tool can be used for health care provider profiling to identify outliers for quality improvement purposes.

Figure 1

The Calibration of the MARC Model When Applied to the NEDSS Data. The dotted line represents perfectly calibrated predictions. The observed admission rates are plotted against the expected admission rates for each decile of predicted admission probability. The difference between the circles and the dotted line represents over- or underprediction of actual risk of admission. MARC, Multicenter Airway Research Collaboration; NEDSS, National Emergency Department Safety Study.