Objectives: Accurate measurement of asthma severity is critical for research evaluating asthma health outcomes. There are, however, no widely accepted asthma severity measures. A severity-of-asthma score, which is based on self-reported information, was previously developed and validated in subjects recruited from pulmonary and allergy subspecialty practices. The purpose of this study was to validate the severity-of-asthma score in subjects treated by family practice physicians and to compare asthma severity in subjects treated by family practitioners (n = 150) with those seen by allergists (n = 217) and pulmonologists (n = 384).
Methods: The study was an ongoing panel study of adults with asthma. Subjects were a random sample of board-certified family practice, allergy, and pulmonary physicians. Each physician registered patients with asthma aged 18 to 50 years. Of 869 subjects registered, 751 (86%) completed structured telephone interviews. The family practice panel was recruited approximately 3 years after the subspecialty panel.
Results: In the family practice subjects, the severity-of-asthma score demonstrated internal consistency (Cronbach's alpha 0.76) and concurrent validity, correlating strongly with asthma-specific quality of life, SF-36 General Health and Physical Functioning scales, and subject-perceived asthma severity. After controlling for demographic characteristics, a 5-point score increment was associated with increased emergency department visits, urgent physician visits, and restricted activity days. The mean severity score was highest in the pulmonary group (11.8 +/- 6.3), followed by the allergy (10.3 +/- 5.3) and family practice (9.3 +/- 5.5) groups.
Conclusions: The severity-of-asthma score was a valid measure in generalist-treated subjects. Asthma severity varied significantly by physician specialty.