An 18-item standardized Asthma Quality of Life Questionnaire-AQLQ(S)

The purpose of the present study was to examine the validity and reliability of the Asthma Quality of Life Questionnaire-AQLQ(S) in a sample of 160 Greek patients with asthma. Following evidence for sample-specific validity, the AQLQ(S) model was examined through exploratory and confirmatory factor analysis. An 18-item AQLQ(S) with the four factors of symptoms, activity limitations, sleep, and exposure in environmental stimuli fits the data (chi(2)/df ratio = 2.26, NNFI = 0.92, CFI = 0.94, SRMR = 0.05). The 18-item AQLQ(S) showed a high internal consistency (Cronbach' a coefficient ranged from 0.83 to 0.96) and high 9-week test-retest reliability (overall r = 0.88, ICC = 0.94). Responsiveness was confirmed throughout 2X2 ANOVA and 2X2 MANOVA, with respect to the total score (F = 42.30, P < 0.05), and the four AQLQ(S) factors (Wilks' lambda = 0.68, F = 17.59, P < 0.05). The cross-sectional correlations between the 18-item AQLQ(S) and the: (1) FEV1% predicted and (2) Borg scale were low and moderately high, respectively. In conclusion, the 18-item AQLQ(S) derived from exploratory and confirmatory factor analysis appeared to have sufficient construct validity, cross-sectional validity, responsiveness, satisfactory test-retest reliability and internal consistency evidence for the Greek sample of adults with asthma.