Guidelines for the clinical management of asthma base specific treatment recommendations on the assessment of disease severity. Thus, the accuracy of such assessments is essential for proper clinical management. The consistency of asthma severity assessment in patients with difficult-to-treat disease is unknown.

The objectives of this analysis were to compare the asthma severity assessment according to 3 methodologies in patients from The Epidemiology and Natural History of Asthma: Outcomes and Treatment Regimens study.

Asthma severity on the basis of the National Asthma Education and Prevention Program and the Global Initiative for Asthma guidelines was compared with physician assessment and benchmarked against asthma-related health care use. Guideline-based asthma severity symptom components were derived from patient-reported questionnaires. Lung function levels were determined by prebronchodilator FEV₁ measurements; asthma-related medication and recent health care use were reported by patients.

There was a clear lack of agreement among the asthma severity assessment modalities. Asthma severity was associated with asthma-related health care use, and patients considered to have severe asthma according to both sets of guidelines and physicians’ assessment had the highest health care and medication use.

Classification of asthma severity on the basis of current asthma symptoms and lung function may be useful but not completely reflective of a patient’s true asthma condition. Clinical assessment of asthma severity should consider a patient’s medication use and consumption of health care resources for asthma exacerbations. Additional studies that apply criteria for asthma severity longitudinally are needed to support recommendations for optimal assessment of asthma severity.