[COPD: criteria for diagnosis and classification of disease severity]

In the guideline proposed by WHO (GOLD) or by the Japanese Respiratory Society (RS), the diagnosis of COPD is simply made when FEV1/FVC (FEV %) of a given subject after inhalation of short-acting bronchodilator is below 70%. On the other hand, on grounds of measured FEV1/predicted FEV (%FEV1), the disease severity of COPD is categorized into four stages including I (mild), II (moderate), III (severe), and IV(very severe). In addition, very special category defined as stage zero (at-risk group) has been proposed in both guidelines. However, the above-mentioned criteria have many impediments as they are too simple for diagnosing and classifying COPD with a complicated pathophysiology. In this paragraph, the attempt is made not only to comment on the diagnosis criteria and classification of disease severity of COPD provided in GOLD and JRS guidelines but also to investigate the details of the impediments existing in both guidelines.