Breathlessness or health status in chronic obstructive pulmonary disease: the impact of different definitions

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.

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.

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.

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.