Background and objective: Although improving health status is one important aim in managing asthmatic patients, few studies have evaluated their health status longitudinally. Therefore, we examined longitudinal changes in health status of asthma patients, and compared them with changes in physiological measures.
Methods: Eighty-seven outpatients with stable asthma after 6 months of treatment were recruited. Health status using the Asthma Quality of Life Questionnaire (AQLQ) and the St. George's Respiratory Questionnaire (SGRQ), pulmonary function, peak expiratory flow (PEF) values, and airway hyperresponsiveness (AHR) were evaluated at entry and every year over a 5-year period.
Results: Using mixed effects models to estimate the slopes, the overall AQLQ score declined statistically at a mean rate of 0.06 units/year (P=.0091). However, this decline did not reach a clinically significant level at 5 years. The total SGRQ score did not change significantly (P=.54). Although the forced expiratory volume in 1 sec declined at a mean rate of 53 mL/year, the PEF variability and AHR improved significantly.
Conclusion: Health status was clinically stable over the 5-year study period in patients with asthma, which contrasted with the changes in the physiological outcome measures. As a patient centered outcome measure, health status should be followed separately.