Validation of the asthma quality of life questionnaire with momentary assessments of symptoms and functional limitations in patient daily life

BACKGROUND: The ecological momentary assessment method may collect more accurate data about a patient's symptoms and functioning during the patient's normal daily life than does a retrospective measurement method such as the standardized Asthma Quality of Life Questionnaire (AQLQ-S), which relies on the patient's recollections of symptoms and functioning. OBJECTIVE: To determine how well the AQLQ-S predicts actual asthma symptoms and functional limitations in patients' daily lives. METHODS: With 91 patients with asthma, we measured quality of life at baseline with the AQLQ-S. Each participant then carried a palm-top computer for 1 week, which signaled the patient 5 times a day to complete a momentary assessment of his or her asthma symptoms, mood, activities, and peak expiratory flow. Once a day, upon awakening, the participants were asked to enter data on their sleep and nocturnal asthma symptoms. RESULTS: The AQLQ-S scores were strongly associated with the momentary assessments of asthma symptoms and patient functioning. The unstandardized slope value indicates, for each 1-unit increase in quality of life, the corresponding change in the outcome variable (in the original units of measurement). Specifically, each 1-unit increase in quality of life was associated with better ambulatory outcomes (assessed on a 7-point scale): fewer coughing and wheezing symptoms (unstandardized slope = -0.44, P <.001); less symptom interference with sleep (unstandardized slope = -0.48, P <.001); less negative affect (unstandardized slope = -0.65, P =.04); and fewer activity restrictions (unstandardized slope = -0.54, P <.001). An increase in quality of life did not significantly predict peak expiratory flow (unstandardized slope = 11.53 L/min, P =.10). CONCLUSIONS: With ecological momentary assessment we found that the AQLQ-S is a valid tool for assessing asthma symptoms and functional limitations. The AQLQ-S scores correctly predicted asthma symptoms, mood, sleep-interference, and activity restrictions in asthma patients' daily lives over a 1-week interval. These data support the AQLQ-S in the clinical management of asthma.