Objective: To identify determinants of pulmonary
function and health-related quality of life (HRQOL) to better
understand disease severity in patients with asthma and COPD.
Design: Observational study.
Dutch general practice.
Patients: We studied 837
asthma patients and 231 COPD patients.
association between pulmonary function and HRQOL was poor for asthma
(β = 0.10) and COPD (β = 0.19). Multivariately, in asthma,
lower pulmonary function was associated with male gender, region of
living, current smoking, use of inhaled short-acting bronchodilators,
longer duration of disease, and higher diurnal variation in peak
expiratory flow. In COPD, lower pulmonary function was associated with
male gender, use of inhaled bronchodilators, more days and nights
disturbed by respiratory complaints, not wheezing, and bronchial
hyperresponsiveness. Reduced HRQOL was associated most strongly with
more days and nights disturbed by respiratory complaints and dyspnea in
both asthma and COPD. In asthma, additional associations were found
with younger age, lower educational level, region of living,
comorbidity, use of inhaled bronchodilators and corticosteroids,
wheezing, chronic cough, sputum production, and bronchial
hyperresponsiveness. In COPD, lower age, not smoking, chronic cough,
and sputum production were associated with reduced HRQOL.
Conclusions: Pulmonary function and HRQOL appear to
highlight different aspects of disease severity in asthma and COPD.
Therefore, both measures should be taken into account in order to get a
complete picture of severity of disease.