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.