Prevalence of chronic obstructive pulmonary disease and risk factors in smokers and ex-smokers

OBJECTIVE: To estimate the prevalence of chronic obstructive pulmonary disease (COPD) in smokers and ex-smokers over 40 years of age and describe the associated risk factors. MATERIAL AND METHODS: A cross-sectional descriptive study at primary care level in which 444 current or ex-smokers 40 years of age or older were enrolled. Spirometry was performed with all subjects. If the ratio of forced expiratory volume in 1 second to forced vital capacity (FEV1/FVC) was less than 70%, a bronchodilator test was performed and spirometry was repeated after 2 inhalations of terbutaline (500 mug/dose). If the FEV1/FVC ratio continued to be less than 70% and FEV1 less than 80% of predicted, COPD was diagnosed. Age, sex, smoking, age smoking began, index of smoking history (packs per day x years smoking) and attempts to quit smoking were also recorded. RESULTS: The patients' mean age was 53.5 years and 65.8% were men. At the time of the study, 248 subjects (55.9%) were current smokers. The median age smoking began was 16.5 years and the median pack-years index was 26.7. At least 1 attempt to quit had been made by 72.1% of the patients. COPD was diagnosed in 70 subjects (24 with the diagnosis previously established), representing a preNalence of 16.4% (95% confidence interval, 12.9-19.9). COPD was serious in 10%. A multifactorial analysis indicated that age and smoking history in pack-years were significantly associated with COPD. CONCLUSIONS: The prevalence of COPD in our study is slightly higher than in other studies, although selection bias may hake affected our results given that we were unable to contact 11.9% of the population sample. Almost two thirds of cases had not been previously diagnosed. Two major risk factors are age and cumulative tobacco consumption.