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

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.

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 g/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 year) and attempts to quit smoking were also recorded.

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 prevalence 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.

The prevalence of COPD in our study is slightly higher than in other studies, although selection bias may have 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.