The RAD score: a simple acute asthma severity score compares favorably to more complex scores.

BACKGROUND: Acute asthma severity scores facilitate assessment and implementation of timely and appropriate therapy for pediatric patients but are complex and challenging for clinicians to use at the bedside.
OBJECTIVE: To assess whether a simple, bedside acute asthma severity score comprising 3 standard clinical measures performs as well as more comprehensive asthma scores.
METHODS: We prospectively enrolled participants 5 to 17 years of age with acute asthma exacerbations. We recorded 3 asthma scores at baseline and after 2 hours of treatment: the Pediatric Asthma Severity Score (PASS), the Pediatric Respiratory Assessment Measure (PRAM), and the RAD score (Respiratory rate; Accessory muscle use; Decreased breath sounds). We assessed each score for criterion validity in predicting baseline percent forced expiratory volume in 1 second (%FEV(1)) and for responsiveness in predicting change of %FEV(1) after 2 hours of treatment using multiple linear regression models adjusted for age, race, sex, and Global Initiative for Asthma chronic control.
RESULTS: Of 536 participants included for analyses, median age was 8.8 years, 60% were male, and 58% were African American. The 3 acute asthma scores demonstrated similar criterion validity to explain variation of baseline %FEV(1) (R(2): 0.434 [PASS]; 0.462 [PRAM]; 0.426 [RAD]), but none demonstrated clinically significant responsiveness to change in %FEV(1) (R(2): 0.109 [PASS]; 0.106 [PRAM]; 0.139 [RAD]).
CONCLUSIONS: The RAD score, comprising 3 routinely measured bedside clinical parameters, is a simple and easily used instrument for assessing the severity of an acute asthma exacerbation and has comparable criterion validity and improved responsiveness when compared with 2 more complex acute asthma scores.