The impact of heart failure on the classification of COPD severity

Pulmonary restriction-a reduction of lung volumes-is common in heart failure (HF), rendering severity grading of chronic obstructive pulmonary disease (COPD) potentially problematic in subjects with both diseases. We compared pulmonary function in patients with either HF or COPD, or the combination to assess whether grading of COPD using the Global Initiative of Chronic Obstructive Lung Disease classification is hampered in the presence of HF.

In 2 cohorts involving 591 patients with established HF and 405 with a primary care diagnosis of COPD, the presence of HF and COPD was assessed according to guidelines. HF severity was staged according to the NYHA classification system into Classes I-IV. COPD was diagnosed if the ratio of post-bronchodilator forced expiratory volume in 1 second and forced vital capacity (FEV1/FVC) was <0.70, and categorized in GOLD stages I-IV according to post-bronchodilator-predicted FEV1 levels (FEV1% ≥80%; 50-79%; 30-49%; <30%). In total, 557 patients with HF only, 108 with HF+COPD, and 194 with COPD only were studied. Patients, who had neither HF nor COPD according to definition, or HF with reversible obstruction in post-bronchodilator pulmonary function tests were excluded from this analysis (n = 137). Compared with COPD only, patients with HF plus COPD had higher levels of post-bronchodilator FEV1/FVC (median [quartiles] 0.57 [0.47-0.64] vs 0.62 [0.55-0.66] and lower total lung capacity % (115 [104-126]% vs 105 [95-117]%, P < .001) P < .001), but comparable levels of post-bronchodilator FEV1% (70 [56-84]% vs 68 [54-80]%, P = .22) and thus similar distributions of GOLD stages I-IV in both groups (24/56/19/4% vs 31/50/19/1%, P = .57). In patients with HF only, 25% exhibited pre-bronchodilator FEV1% levels of <80% (FEV1% 94 [80-108]%), despite a pre-bronchodilator FEV/FVC ratio ≥0.7 in this group. The reduction of FEV1 in patients with HF only was associated with HF severity.

In stable HF, FEV1 may be significantly reduced even in the absence of "real" airflow obstruction. In this situation, diagnosing COPD according to GOLD criteria (based on FEV1/FVC) still seems feasible, because both FEV1 and FVC are usually decreased to an equal extent in HF. However, classifying COPD based on FEV1 levels may overrate obstruction severity in patients with combined disease (HF plus COPD), and thus may lead to unjustified use of bronchodilators.