SENSITIVITY OF QUALITY-OF-LIFE DOMAINS AND CONSTRUCTS TO LONGITUDINALCHANGE IN A CLINICAL-TRIAL COMPARING SALMETEROL AND PLACEBO IN ASTHMATICS

The quality of life (QOL) benefits of salmeterol versus placebo were c ompared in a double-blind, multicentre study using the Living with Ast hma Questionnaire (LWAQ) which was scored in three different ways. Fir st, the overall LWAQ score showed that salmeterol enhanced QOL compare d to placebo. Second, when the LWAQ was analysed in terms of its two c onstruct subscales we found, as predicted previously, that the Problem construct was more sensitive to longitudinal change compared with the Evaluation construct. Third, when the LWAQ was analysed in terms of i ts 11 domain subscales we found a significant improvement for salmeter ol compared with placebo on three domains, Sport, Sleep, and Work and other activities. Analysing clinical trial results in terms of constru ct subscales and domain subscales provides different kinds of informat ion each of which is useful. Analysis in terms of overall QOL scores i s less informative.