MEASUREMENT CHARACTERISTICS OF 2 ASTHMA SYMPTOM DIARY SCALES FOR USE IN CLINICAL-TRIALS

The measurement characteristics of two asthma symptom diary scales dev eloped for use as health outcome measures in clinical trials of asthma therapy were investigated, A daytime diary scale was designed to capt ure the frequency and inconvenience of day-time asthma symptoms and th eir effects on activities, and a nocturnal asthma symptom diary scale was designed to capture awakenings with asthma symptoms, The internal consistency, reliability, validity and responsiveness of both asthma d iary scales were assessed in 346 adult asthma patients in two placebo- controlled clinical trials of an investigational asthma therapy, a leu kotriene biosynthesis inhibitor, The daytime symptom scale showed suff icient internal consistency (0.90-0.92), and the daytime and nocturnal symptom scales showed sufficient test retest reliability (0.69-0.87), Construct validity was demonstrated by generally moderate-to-strong c orrelations for changes in the diary scales with changes in other meas ures of asthma status, such as forced expiratory volume in one second (FEV1), peak expiratory flow (PEF), and puffs of beta-agonist inhaler, Both scales demonstrated significant responsiveness to change in asth ma due to therapy in one of the clinical trials. Based on these result s, the daytime and nocturnal asthma symptom diary scales show measurem ent characteristics appropriate for use as asthma outcome measures in clinical trials of asthma therapy.