A 3-year longitudinal study of asthma quality of life in undiagnosed and diagnosed asthma patients.

Setting: Juniper's Asthma Quality of Life Questionnaire with standardised activities (AQLQ(S)) is commonly used to evaluate the effect of interventions in pharmaceutical trials, but rarely, if ever, used clinically in long-term follow-up of undiagnosed or diagnosed asthma patients.

Design: The AQLQ(S) was administered to 493 asthma patients who were randomised to treatment in primary or specialist care over a 3-year period.

Results: Of the 493 patients, 249 had not been diagnosed before screening and 244 had a doctor's diagnosis of asthma. At entry, known patients had a lower total AQLQ(S) score (median 6.03, 95%CI 3.9-7.0) than undiagnosed patients (median 6.54, 95%CI 4.8-7.0, P < 0.001). Treatment with inhaled corticosteroids induced lower scores (median 5.7, 95%CI 3.5-7.0) than no treatment (median 6.5, 95%CI 4.8-7.0, P < 0.01). Half of the patients (n = 260) were randomly invited to participate in a follow-up survey in a specialist setting. In the first 3 months of follow-up, a decrease in AQLQ(S) score among the undiagnosed patients (median -0.24, 95%CI -1.6-0.9, P = 0.02) was observed. After 3 years, the score improved significantly (by >0.5 points) in 45% of the undiagnosed patients (n = 107) compared to 26% of the known patients (n = 116, P < 0.05).

Conclusion: The initial total AQLQ(S) score was higher in undiagnosed asthma patients. After diagnosis the AQLQ(S) initially decreased but then increased, followed by an overall improvement that exceeded that of the known asthma patients.