[Prognostic markers of COPD. Role of comorbidity].

A chronic disease such as chronic obstructive pulmonary disease (COPD) will inevitably have biological markers influencing its natural history or progression. The most extensively studied marker is forced expiratory volume in 1 second (FEV(1)), classically recognized as the best prognostic indicator of the disease. Other physiopathological variables are also known to have prognostic value. The course of COPD shows several distinct patterns but data are lacking on the natural history of this disease and the ability to predict which patients will show greater or lesser progression. In addition to FEV(1), there are other physiological markers of disease progression, such as gas interchange, air trapping, and pulmonary hypertension. The present article reviews the characteristics of all these markers, as well as those of two other categories: clinical markers, such as nutritional status, exercise capacity, the BODE index, which combines four physiopathological and clinical parameters, and the occurrence or absence of frequent exacerbations. Finally, a group of biological markers, potentially implicated in COPD, such as C-reactive protein, oxidative stress and other variables affecting changes in skeletal muscle, are described. COPD also predisposes affected individuals to the presence of other associated diseases or comorbidities, which can occur more frequently because of the presence of COPD itself and can potentially influence the outcome of this disease.