慢性阻塞性肺部疾病是一常見可預防和治療的疾病，其特點是漸進、持續性的氣流受限。當呼吸道或肺受到有毒的顆粒和氣體刺激後，會引起炎症反應，使結構改變及氣道狹窄，進而使氣流受限、氣體滯積及肺過度膨脹，最後導致第一秒用力呼氣量下降。若未能及早診斷或治療，疾病將進展至全身性的疾病，最後死亡，這可能會造成嚴重的社會負擔。以往診斷慢性阻塞性肺部疾病主要是靠第一秒用力呼氣量，但，近年發現第一秒用力呼氣量並不能代表疾病複雜度及嚴重度。故，開始使用改良過的英國醫學研究會問卷或慢性阻塞性肺部疾病評估測試評估病人健康狀況，加上氣流受限嚴重程度及未來惡化風險來評估慢性阻塞性肺部疾病。新的分類將慢性阻塞性肺部疾病分成A、B、C、D四類，並依照這四類給予不同的治療，期望透過早期診斷及治療，可以降低疾病的惡化，而減少社會負擔並增進病人生活品質。

Chronic obstructive pulmonary disease (COPD), a common preventable and treatable disease, is characterized by persistent airflow limitation. The respiratory tract or lung suffered from the noxious particles and gas stimulation will lead to chronic inflammatory to cause structural changes and narrowing of respiratory tract, and then make airflow limitation, air trapping and lung hyperinflation, and finally result in declining forced expiratory volume in one second (FEV1). If the diagnosis or treatments were not early undergone, then the single disease will turn into the systemic disease and lead to death, which may bring the serious social burden. FEV1 was principally used to diagnose with chronic obstructive pulmonary disease in the past, but it is not able to represent the complexity and severity of the disease in recent years. Nowadays, the modified British Medical Research Council (mMRC) questionnaires or COPD assessment test (CAT) is used to evaluate COPD with the patient’s symptoms, severity of airflow limitation and future exacerbation risk. The COPD patients are classified into four groups as A, B, C, and D according to the new COPD category with corresponding treatments to offer in order to slow down the progression of the comorbidities and decrease the social burden and improve the quality of life of patients through early diagnosis and treatment.