Risk factors for chronic obstructive pulmonary disease in a European cohort of young adults

RATIONALE: Few studies have investigated the factors associated with the early inception of chronic obstructive pulmonary disease (COPD).OBJECTIVE: We investigated COPD risk factors in an international cohort of young adults using different spirometric definitions of the disease.METHODS AND MEASUREMENTS: We studied 4,636 non-asthmatic subjects who had pre-bronchodilator FEV1/FVC measured in the European Community Respiratory Health Survey both in 1991-1993 (when they were 20-44 years old) and in 1999-2002. COPD was defined according to the GOLD fixed cut-off criterion (FEV1/FVC<0.70), and two criteria based on the Quanjer and LuftiBus reference equations (FEV1/FVC<lower limit of normal (LLN)). COPD determinants were studied using 2-level Poisson regression models.MEASUREMENTS AND MAIN RESULTS: COPD incidence ranged from 1.85 (LLN-Quanjer) to 2.88 (GOLD) cases/1,000/year. Although about half of the cases had smoked less than 20 pack-years, smoking was the main risk factor for COPD, and it accounted for 29% to 39% of the new cases during the follow-up. Airway hyper-responsiveness (AHR) was the second strongest risk factor (15% to 17% of new cases). Other determinants were respiratory infections in childhood and a family history of asthma, whereas the role of sex, age and of being underweight largely depended on the definition of COPD used.CONCLUSIONS: COPD may start early in life. Smoking prevention should be given the highest priority to reduce COPD occurrence. AHR, a family history of asthma and respiratory infections in childhood are other important determinants of COPD. We suggest the need for a definition of COPD that is not exclusively based on spirometry.