Abstract
The Respiratory Distress Assessment Instrument (RDAI) and Respiratory Assessment Change Score (RACS) are frequently used in bronchiolitis clinical trials, but evidence is scarce on their suitability as outcome measures.We investigated their reliability,validity,and responsiveness.
We used data from two bronchiolitis studies conducted in 8 Canadian pediatric emergency departments (ED).We assessed RDAI test-retest agreement and inter-rater reliability using limits of agreement (LoA) and Intraclass Correlation Coefficients (ICC).RDAI construct validity was evaluated by testing hypotheses on its scores association with respiratory rate,SatO2,and hospitalization, using correlation coefficients and multivariable analysis.We assessed RDAI/RACS responsiveness using anchors of change based on these constructs and measures such as the area under the curve (AUC).
1765 participants were included. RDAI test-retest LoA were -3.80 - 3.64 (20% of the range of the scale),inter-rater ICC was 0.93.Correlation of baseline RDAI scores with respiratory rate was 0.38, p<0.001. RDAI scores increased in lower SatO2 categories (p<0.001).Higher RDAI scores were associated with hospitalization (OR 1.36 [95% CI 1.26-1.47]);scores differed between participants discharged,admitted,or staying in the ED (p<0.001).Formulated hypotheses for responsiveness were confirmed,with moderate responsiveness (RDAI:AUC 0.64 to 0.70; RACS:AUC 0.72).
RDAI has good discriminative properties, but its considerable test-retest measurement error limits its use as a trial outcome measure.RDAI and RACS are fairly valid and responsive measures of acute respiratory distress, but don′t encompass all elements of bronchiolitis severity.
- © 2014 ERS