linguistic:translation
Subtypes

It has since been recognized that COPD is more complex, with a diverse group of disorders of differing risk factors and clinical courses that has resulted in a number of subtypes or phenotypes of COPD being accepted and proposed. The two classic emphysematous and chronic bronchitic phenotypes are fundamentally different conditions with unique underlying mechanisms. Another subtype of COPD, categorized by some as a separate clinical entity, is asthma-COPD overlap, which is a condition sharing clinical features of both asthma and COPD. Spirometry measures are inadequate for defining phenotypes and chest X-ray, CT and MRI scans have been mostly employed. Most cases of COPD are diagnosed at a late stage and the use of imaging methods would allow earlier detection and treatment.

The identification and recognition of different phenotypes can guide appropriate treatment approaches. For example, the PDE4 inhibitor roflumilast is targeted at the chronic-bronchitic phenotype.

Two inflammatory phenotypes show a phenotype stability: the neutrophilic inflammatory phenotype and the eosinophilic inflammatory phenotype. Mepolizumab, a monoclonal antibody, has been shown to have benefit in treating the eosinophilic inflammatory type rather than the use of oral corticosteroids, but further studies have been called for.

Another recognized phenotype is the frequent exacerbator. The frequent exacerbator has two or more exacerbations a year, has a poor prognosis and is described as a moderately stable phenotype.

A pulmonary vascular COPD phenotype has been described due to cardiovascular dysfunction. A molecular phenotype of CFTR dysfunction is shared with cystic fibrosis. A combined phenotype of chronic bronchitis and bronchiectasis has been described with a difficulty noted of determining the best treatment.

The only genotype is the alpha-1 antitrypsin deficiency (AATD) genetic subtype and this has a specific treatment.