[Smoking and chronic obstructive pulmonary disease: attributable risk determination]

Smoking is the main risk factor for Chronic Obstructive Pulmonary Disease (COPD), an important cause of morbidity and mortality.

To estimate smoking attributable risk and population attributable risk in COPD patients attended in Public Health Services of Santiago.

A case control study matched by sex and age was carried out. Crude and adjusted attributable risks as well as population attributable risk were estimated, controlled by potential confounders and by interaction variables.

Mean ages for cases and controls were 68 and 67 years respectively. When compared to the control group, COPD patients had a higher smoking prevalence (at least 100 cigarettes in their life span: 89.7% vs 60.3%; p <0.01). Among COPD patients, heavy smokers proportion was 4 times higher than in controls, they smoked for more years (43 vs 31; p <0.01) and more cigarettes per day (18 vs 5; p <0.01). Adjusted attributable risk was 87% (95% Confidence Interval (CI): 63.7-94.8). If a patient smoked at least 100 cigarettes in his/her life span and this risk was 92.7% (CI: 82.4-96.9) for heavy smokers. Projecting this index to Santiago inhabitants, about 87,000 individuals older than 40 years would be suffering COPD due to smoking.

This article confirms the strong association between smoking and COPD. Attributable risks are high and significant, even when they are adjusted by confounding variables. Women had a higher risk than men, at lower levels of tobacco consumption.