COPD and the Concept of Control

A recent article suggests that comparing 2 or more observations of a patient’s COPD symptoms over time can help clinicians learn why patients lose control of the disease.

Several organizations concerned with improving outcomes for chronic obstructive pulmonary disease (COPD) patients have proposed a phenotype concept that classifies patients into subgroups. A phenotype is “a single or combination of disease attributes that describe differences between individuals with COPD as they relate to clinically meaningful outcomes.”¹ Theoretically, the patient’s phenotype would direct care and also generalize prognosis. A letter to the editor published online ahead of print on July 25, 2014, in the European Respiratory Journal suggests that the use of a new concept—the concept of COPD control—is a better approach.

Consider 2 patients of the same age who have identical symptom constellations and levels of airway obstruction. Both have had 2 exacerbations in the current year. The authors suggest that while phenotypically, these patients look the same, they may be quite different. One may have experienced 6 exacerbations in the previous year, so the decrease to 2 exacerbations represents improvement. The other may have been exacerbation-free in the previous year; his condition represents loss of control.

This article helps health care clinicians to understand current theories about COPD and organize their thoughts about the way health care categorizes and treats patients. It redefines control, and redirects attention to the reasons why patients lose control. The authors suggest that control has 2 elements:

• Impact, which refers to the current clinical situation, is an assessment represented by the question, ‘‘How are you today?’’ Impact is static.
• Stability, which is a dynamic measure, is a comparison by clinicians of least 2 observations over time. It is represented by the question, ‘‘How are you compared with the last visit?’’

Together, impact and stability create “control of COPD.’’

Patients lose control of their COPD for many reasons, a few of which are of tremendous interest to pharmacists. For example, they may continue or resume smoking, have bad inhaler technique, or comply poorly with their treatment plans. When no cause can be identified or corrected, maintenance medications may need to be adjusted. Long-term oxygen therapy may also be needed.

The authors suggest that their approach to COPD control is simpler than methods proposed by others, and may allow improved individualization of therapy. They indicate that phenotypic classification has a place, especially at the initial visit, but that at subsequent visits, evaluation of control can frame the patient’s progress. Regardless of whether readers agree or disagree with these authors, the article stimulates thought.

Reference

• Han MK, Agusti A, Calverley PM, et al. Chronic obstructive pulmonary disease phenotypes. Am J Respi Crit Care Med. 2010;182(5):598-604.