Is the asthma quality of life questionnaire a useful measure for low- income asthmatics?

The purpose of this study was to evaluate the reliability and validity of the Asthma Quality of Life Questionnaire (AQLQ) in a population-based sample of low-income adults with asthma. A total of 112 subjects (46 African American, 66 Caucasian; mean age = 33 ± 9 yr; 26% male) were recruited from the Baltimore County, Maryland and Atlanta, Georgia metropolitan areas. Internal consistency reliability (Cronbach's α) was high for the overall scale (0.96); 2-wk reproducibility (intraclass correlation, ICC) was 0.82 (n = 38). Overall score was significantly correlated with FEV₁ percentage of predicted (r = 0.20), and the Asthma Disease Severity Scale (r = -0.38). Correlations between overall score and the SF-36 Physical Component Summary (r = 0.49), SF-36 Mental Component Summary (r = 0.37), Cantril's Ladder (r = 0.23), and the Health Utilities Index (r = 0.22) supported the validity of the AQLQ in this sample. Comparison of reliability and validity estimates across racial groups found few substantive differences. Internal consistency, reproducibility, and validity estimates found in this sample were consistent with those of a reliable and valid measure and were comparable to those found in other populations. These results suggest the AQLQ is a useful indicator of health-related quality of life in low-income asthmatics.