Breathlessness or Health Status in Chronic Obstructive Pulmonary Disease: The Impact of Different Definitions

Abstract

Objective: The GOLD 2011 report recommends the use of symptoms, exacerbation history, and FEV1% predicted to categorise patients into groups A–D. We investigated the choice of mMRC or CAT on category assignment and characterization of the categories. Methods: Patients were prospectively recruited from tertiary hospitals in China, as part of the INTACT study, with a prior diagnosis of COPD. The GOLD categories were defined using mMRC and CAT, along with exacerbations in the previous year, and FEV1% predicted. Results: 1,465 patients were included. The most prevalent group was group D. However, proportions of patients categorised into groups A to D differed depending on symptom instruments. The use of CAT resulted in more patients being placed into groups B and D. Cardiac co-morbid conditions, particularly ischaemic heart disease, heart failure, and arrhythmia were highly prevalent in groups B and D. Group B appeared to have a similar burden of cardiac co-morbidities to group D, in spite of a higher FEV1 level. Although mMRC assigned a smaller proportion of patients to groups B and D, the patients it did assign had a higher burden of cardiac co-morbidities than patients assigned by CAT. When patients were assessed according to LLN, 14.2% had normal airflow according to ECSC 1993 equations, with 12.6% having normal airflow according to GLI 2012 formulae. Conclusions: The choice of symptom assessment is one potential confounder impacting the patient assignment. Breathlessness may be an important marker of overall disease severity, indicating the presence of cardiac co-morbidities in the GOLD categories.