COPD symptoms/diagnosis and smoking habits: a 25 yr population-based survey

Background: smoking habits are strongly associated with Chronic Obstructive Pulmonary Disease(COPD) symptoms/diagnosis but few epidemiological surveys on general population samples estimated such relationship over a long time interval. Aim: to assess the association between long term smoking habits and COPD symptoms/diagnosis over a 25 yr period. Methods: a general population sample participated in 3 cross-sectional surveys carried out in Central Italy (Pisa) in 1985-88, 1991-93, 2009-11. A standardized questionnaire on health status and risk factors was used. Chi-square test was used to compare unchanged long term smoking habits [non smokers (NS), ex smokers (ES), current smokers (CS)] and the change in COPD symptoms/diagnosis prevalence from 1st to 3rd survey (COPD symptoms: persistent/incident vs never/remittent; COPD diagnosis: persistent/incident vs never/remittent). Multiple logistic regression (MLR) models were run to analyse the association between COPD and smoking habits adjusted for gender, age, lifetime passive smoke exposure and work exposure. Results: 575 subjects had not changed their smoking habit: 55.8% NS, 25.8% ES, 18.4% CS. Persistent/incident COPD was significantly different among NS, ES, CS: 30.8% vs 37.2% and 45.3% for symptoms; 6.9% vs 18.9% and 17.9% for diagnosis. MLR showed a significant higher risk of having persistent/incident COPD diagnosis in CS (OR 3.12) and ES (OR 2.24) and of having persistent/incident COPD symptoms in CS (OR 1.75). Conclusions: this study showed that past/current smokers had higher risk of suffering from COPD symptoms/diagnosis over a period of 25 yr and confirmed the need to refrain from smoking and to quit smoking as soon as possible.