Will COPD be divided into sub-groups?

It's possible that chronic obstructive pulmonary disease (COPD) may soon be classified into subgroups.  This may be necessary because certain features of the disease may require unique treatments.

For instance, studies seem to show that COPD patients who respond well to bronchodilators, or who show partial reversibility with bronchodilators, may also respond well to inhaled corticosteroids, according Ortega et al.

These patients tend to present with hyperactive airways, similar to asthma.  They may also present with elevated eosinophils in induced sputum samples, and have higher concentrations of exhaled nitric oxide, similar to patients with asthma.

Furthermore, COPD patients with positive reversibility tend to have a slower annual reduction in FEV1, and may be a predictor of longevity.

However, COPD patients with a positive response to bronchodilators have a higher risk of developing respiratory symptoms, and, as Ortega et al concludes, a shorter time to exhaustion in endurance exercise testing, and a shorter shuttle-walk distance.

The study notes that about 70-90% of asthmatics have exercise induced bronchospasm, and that these patients often respond better to exercise after inhalation of bronchodilator.  COPD patients with positive reversibility respond in a similar way with exercise post bronchodilator.

Ortega et al suggests a possible treatment for dyspnea caused by exertion may be bronchodilators after exertion, as this seems to improve lung function.

So, COPD patients with positive reversibility may be classified as one subgroup, while COPD patients with negative reversibility may be classified as another subgroup.  Treatment for both groups may be different, requiring different sets of guidelines.

References:

1. Ortega, Francisco, Eduardo Marquez-Martin, Borja Valencia, Pilar Cejudo, Ana Rodriquez, Jose Luis Lopez-Campos, and Emilia Barrot, “Impat of Bronchodilator Responsiveness on Quality of Life and Exercise Capacity in Patients With COPD,” Respiratory Care, January, 2014, volume 59, number 1, pages 81-89