Development and initial validation of the Asthma Severity Scoring System (ASSESS)

Abstract

Background: Tools for quantification of asthma severity are limited.

Objective: We sought to develop a continuous measure of asthma severity, the Asthma Severity Scoring System (ASSESS), for adolescents and adults, incorporating domains of asthma control, lung function, medications, and exacerbations.

Methods: Baseline and 36-month longitudinal data from participants in phase 3 of the Severe Asthma Research Program (NCT01606826) were used. Scale properties, responsiveness, and a minimally important difference were determined. External replication was performed in participants enrolled in the Severe Asthma Research Program phase 1/2. The utility of ASSESS for detecting treatment response was explored in participants undergoing corticosteroid responsiveness testing with intramuscular triamcinolone and participants receiving biologics.

Results: ASSESS scores ranged from 0 to 20 (8.78 ± 3.9; greater scores reflect worse severity) and differed among 5 phenotypic groups. Measurement properties were acceptable. ASSESS was responsive to changes in quality of life with a minimally important difference of 2, with good specificity for outcomes of asthma improvement and worsening but poor sensitivity. Replication analyses yielded similar results, with a 2-point decrease (improvement) associated with improvements in quality of life. Participants with a 2-point or greater decrease (improvement) in ASSESS scores also had greater improvement in lung function and asthma control after triamcinolone, but these differences were limited to phenotypic clusters 3, 4, and 5. Participants treated with biologics also had a 2-point or greater decrease (improvement) in ASSESS scores overall.

Conclusions: The ASSESS tool is an objective measure that might be useful in epidemiologic and clinical research studies for quantification of treatment response in individual patients and phenotypic groups. However, validation studies are warranted.

Keywords: Asthma control; asthma severity classification; psychometric testing; severe asthma; tool development.

Copyright © 2019 American Academy of Allergy, Asthma & Immunology. All rights reserved.

Figures

Figure 1.

Distribution of baseline and longitudinal Asthma Severity Scoring System (ASSESS) scores in all participants, participants according to the modified dichotomous European Respiratory Society/American Thoracic Society definition of severe asthma, and participants according to phenotypic cluster assignment. Data in panels A and B reflect the mean ± SEM.

Figure 2.

Asthma Severity Scoring System (ASSESS) scores in participants with 3 or more exacerbations hospitalization, or intensive care unit admission in the previous year. Boxplot whiskers correspond to the 5th and 95th percentiles. **p<0.001

Figure 3.

Responsiveness of the Asthma Severity Scoring System (ASSESS) score to changes in the Asthma Quality of Life Questionnaire (AQLQ) score between baseline and 12 months, 12 and 24 months, and 24 and 36 months. *p

Figure 4.

Associations between changes in Asthma Severity Scoring System (ASSESS) and Asthma Quality of Life Questionnaire (AQLQ) scores in the replication cohort. Figures on the right are stratified by changes in AQLQ scores. Boxplot whiskers and dashed lines correspond to the 5thand 95th percentiles and the minimal important difference of −2 for ASSESS improvement. *p < 0.05, **p<0.01

Figure 5.

Radar plots depicting changes in individual domains of the Asthma Severity Scoring System (ASSESS) at baseline and after intramuscular triamcinolone. Spikes correspond to individual participants responses. Panels B-D depict changes (mean ± SEM) in FEVi, ACQ7, and ACQ6 scores after triamcinolone in participants in whom ASSESS scores improved (≥2 point decrease), did not change, and worsened (≥2 point increase). **p