Development and validation of an onset of effect questionnaire for patients with asthma

Abstract

A maintenance medication that patients with asthma can feel working shortly after administration could reinforce daily treatment and improve satisfaction, adherence, and outcomes. This study was performed to develop and test a measure assessing patient perception and satisfaction with feeling an asthma medication working right away. Three studies were conducted to develop and evaluate the measure. Study 1 involved qualitative patient interviews to understand the concept of feeling a medication working right away and developed the assessment method and item pool (n = 64). Study 2 examined item clarity and content validity through cognitive interviews (n = 39). Study 3 tested reliability and validity through secondary analyses of data from adults participating in a 12-week, multicenter, double-blind, placebo-controlled phase III trial of mild to moderate persistent asthma (n = 245). A five-item weekly diary, the Onset of Effect Questionnaire, was developed with two items selected as primary: one evaluating whether patients feel their medication working right away and one assessing satisfaction with how quickly they feel their medication begin to work. These items showed 1-week reproducibility (phi = 0.77; 0.70; p < 0.0001), construct validity (relationship with improvement in 15-minute postdose forced expiratory volume in 1 second [FEV₁; p < 0.0001 and symptom severity] p < 0.001) and predictive validity (response after 1 week of treatment predicted 2-week 15-minute postdose FEV₁ [p < 0.0001], Asthma Quality of Life Questionnaire symptom domain [p < 0.05], and Patient Satisfaction with Asthma Medication overall perception of medication [p < 0.0001] and asthma relief subscales [p < 0.0001]). Results suggest that the items are reliable and valid and may be used as end points in clinical trials involving similar patient populations.