Background: Chronic obstructive pulmonary disease (COPD) may have its origin in early life although it manifests clinically in the elderly patient. We tested the hypothesis that a pre-disease state ?pre-COPD?, defined by chronic bronchitis and/or impaired lung function, identifies young adults who will develop COPD later in life.

Methods: We identified pre-COPD in 5218 individuals aged 20-45 years in the Copenhagen General Population Study and Copenhagen City Heart Study and followed them 10 and 25 years for development of COPD (forced expiratory volume in one second [FEV1]/forced vital capacity [FVC]<0.70 and FEV1<80% predicted), and 15 and 40 years for risk of severe exacerbations. A COPD risk score was created by including pre-COPD with smoking and asthma as risk factors.

Results: 8% and 16% with pre-COPD developed COPD after 10 years and 25 years compared to <1% and 8% in those with normal lung function. Half of those with COPD developed the disease from pre-COPD. Adjusted odds ratios were 8.82(95% confidence interval:4.43-17.6) after 10 years and 1.82(1.34-2.46) after 25 years for pre-COPD versus normal lung function. Corresponding hazard ratios were 11.3(2.27-56.6) and 2.10(1.48-2.97) for severe exacerbations. The ability of the COPD risk score to predict COPD and severe exacerbations was high (AUC or Harrell?s C=0.70-0.89). Results were consistent in the Copenhagen General Population Study and Copenhagen City Heart Study.

Conclusions: Our study suggests that presence of pre-COPD in young adults is an important risk factor for COPD later in life and can be used for early identification of susceptible individuals.

Funding: Copenhagen University Hospital ? Herlev and Gentofte.