[The diagnosis of COPD is recommendation dependent]

Different spirometric criteria are recommended to diagnosis chronic obstructive pulmonary disease (COPD): -American Thoracic Society/European Respiratory Society (ATS/ERS), Global initiative for chronic Obstructive Lung Disease (GOLD): a post bronchodilator (PBD) ratio between the 1st second Forced Expiratory Volume and Forced Vital Capacity (FEV1/FVC) < 0.70; -Thoracic Society of Australia and New Zealand (ANZTS): a PBD FEV1/FVC < 0.70 and a PBD FEV1 < 80%; -British Thoracic Society (BTS): a before BD (BBD) FEV1/FVC < 0.70 and a BBD FEV1 < 80%; -Old criterion retained, till 2010, by the French Society of Pneumology (SPLF): a PBD ratio between FEV1 and slow vital capacity < 0.70.

To determine, according to the different recommendations, the percentage of smokers having COPD among a population of smokers of more than 40 Packets/Year (PY) addressed for plethysmography.

The plethysmographic data of 531 consecutive stable male smokers that underwent reversibility testing (400 µg of Salbutamol®) were analyzed.

The mean ± SD of age, cigarettes consumption, PBD FEV1 (%), were, respectively, 61 ± 11 Yr, 64 ± 20 PY and 52 ± 21%. The percentages of subjects having COPD according to the above criteria were 75.5% (SPLF old criterion); 71.2% (ATS/ERS, GOLD); 70.8% (BTS) and 69.7% (ANZTS).

The diagnosis of COPD depends on which guidelines are used for defining the disease. This forms a barrier to early diagnosis, affects public health decisions and wrong planning strategies.