Predictive value of lung function below the normal range and respiratory symptoms for progression of chronic obstructive pulmonary disease

Abstract Background: Chronic Obstructive Pulmonary Disease (COPD) is an insidiously starting disease. Early detection has high priority because of the possibility of early implementation of smoking cessation interventions. An evidence based model for case-finding of COPD is not yet available. Study Objective: To describe the early development of COPD, and to assess the predictive value of early signs (respiratory symptoms, lung function below normal range, reversibility). Design and Methods: In a prospective study, based in general practice, formerly undiagnosed subjects (n=464) were assessed at baseline and at year five for respiratory symptoms and pulmonary function. Odds ratio’s of early signs were calculated (adjusted for age, gender, packyears at baseline, and smoking behaviour during follow-up), and defined as possible indicators of disease progression. Results: Over a five year period, the percentage of subjects with obstruction increased from 7.5% (n=35) at baseline to 24.8% (n=115) at year five. Baseline presence of mild early signs and lung function below normal range were related to an increased risk to develop mild to moderate COPD {GOLD I; OR:1.87 (95% CI [1.22-2.87]), respectively GOLD II; OR:2.08 (95% CI [1.29- 3.37]) to 2.54 (95% CI [1.25-5.19])}at year five. Conclusion: Lung function below normal range and early respiratory signs predict the development and progression of COPD.