Clinical Predictors of Health-Related Quality of Life Depend on Asthma Severity

Abstract

The National Asthma Education and Prevention Program guide-lines define asthma severity before treatment by lung functionand symptoms. It has been assumed, but not demonstrated, thatimprovement in these measures would translate into improve-ment in health-related quality of life (HRQL). Because HRQL is animportant outcome in asthma management, we asked what arethe determinants of HRQL? To address this question, we retro-spectively analyzed HRQL data, as measured by the Juniper AsthmaQuality of Life Questionnaire, in subjects with mild versus moder-ate-severe asthma from two clinical trials. We examined whetherthese traditional clinical outcomes have different relationships toHRQL depending on asthma severity. We also assessed whetherthe relationship between clinical outcomes and HRQL in subjectswith moderate-severe asthma would change when subjects im-proved to mild-moderate disease with controller medication treat-ment. Lung function was not an independent predictor or deter-minant of HRQL at any level of asthma severity, whereas intensityof shortness of breath predicted HRQL at all levels of asthma se-verity. Rescue ␤ -agonist use independently predicted HRQL insubjects with mild asthma, but not in those with moderate-severeasthma. In subjects with moderate-severe asthma who improvedto mild-moderate disease with controller treatment, rescue ␤ -ago-nist use predicted HRQL. We conclude that the independent de-terminants of HRQL vary according to asthma severity and changewith asthma treatment.