Long-term decline in lung function, utilisation of care and quality of life in modified GOLD stage 1 COPD
- 1Division of Pulmonary Medicine, Geneva University Hospitals and University of Geneva, Switzerland
- 2Molecular Epidemiology/Cancer Registry, Institutes of Social and Preventive Medicine and Surgical Pathology, University of Zurich, Switzerland
- 3Institute of Social and Preventive Medicine, University of Basle, Switzerland
- 4Division of Community Medicine and Primary Care, University Hospitals of Geneva, University of Geneva Medical School, Switzerland
- Dr P-O Bridevaux, University Hospitals of Geneva, Division of Pulmonary Medicine, 24 rue Micheli-du-Crest, 1211 Geneva, Switzerland;
- Received 3 December 2007
- Accepted 8 April 2008
- Published Online First 27 May 2008
Background: Little is known about the long-term outcomes of individuals with mild chronic obstructive pulmonary disease (COPD) as defined by the Global Initiative for Chronic Obstructive Lung Disease (GOLD).
Methods: A population cohort of 6671 randomly selected adults without asthma was stratified into categories of modified GOLD-defined COPD (prebronchodilator spirometry). Further stratification was based on the presence or absence of respiratory symptoms. After 11 years, associations between baseline categories of COPD and decline in forced expiratory volume in 1 s (FEV1), respiratory care utilisation and quality of life as measured by the SF-36 questionnaire were examined after controlling for age, sex, smoking and educational status.
Results: At baseline, modified GOLD criteria were met by 610 (9.1%) participants, 519 (85.1%) of whom had stage 1 COPD. At follow-up, individuals with symptomatic stage 1 COPD (n = 224) had a faster decline in FEV1 (−9 ml/year (95% CI −13 to −5)), increased respiratory care utilisation (OR 1.6 (95% CI 1.0 to 2.6)) and a lower quality of life than asymptomatic subjects with normal lung function (n = 3627, reference group). In contrast, individuals with asymptomatic stage 1 COPD (n = 295) had no significant differences in FEV1 decline (−3 ml/year (95% CI −7 to +1)), respiratory care utilisation (OR 1.05 (95% CI 0.63 to 1.73)) or quality of life scores compared with the reference group.
Conclusions: In population-based studies, respiratory symptoms are of major importance for predicting long-term clinical outcomes in subjects with COPD with mild obstruction. Population studies based on spirometry only may misestimate the prevalence of clinically relevant COPD.
See Editorial, p 756
▸ Further information is published online only at http://thorax.bmj.com/content/vol63/issue9
Funding: The Swiss National Science Foundation (grants no 4026-28099, 3347CO-108796, 3247BO-104283, 3247BO-104288, 3247BO-104284, 32-65896.01, 32-59302.99, 32-52720.97, 32-4253.94), the Federal Office for Forest, Environment and Landscape, the Federal Office of Public Health, the Federal Office of Roads and Transport, the canton’s government of Aargau, Basel-Stadt, Basel-Land, Geneva, Luzern, Ticino, Zurich, the Swiss Lung League, the canton’s Lung League of Basel Stadt/Basel Landschaft, Geneva, Ticino and Zurich.
Competing interests: None.
Ethics approval: Ethics committee approval was obtained from the participating centres and from the Swiss Academy of Medical Science.
SAPALDIA Team (Swiss cohort study on Air Pollution and Lung Disease in Adults) Study directorate: T Rochat, U Ackermann-Liebrich, JM Gaspoz, P Leuenberger, LJS Liu, NM Probst Hensch, C Schindler. Scientific team: JC Barthélémy, W Berger, R Bettschart, A Bircher, O Brändli, M Brutsche, L Burdet, M Frey, MW Gerbase, D Gold, W Karrer, R Keller, B Knöpfli, N Künzli, U Neu, L Nicod, M Pons, E Russi, P Schmid-Grendelmeyer, J Schwartz, P Straehl, JM Tschopp, A von Eckardstein, JP Zellweger, E Zemp Stutz. Scientific collaborators at coordinating centers: P-O Bridevaux, I Curjuric, D Felber Dietrich, A Gemperli, M Imboden, D Keidel, P Städele-Kessler.