Abstract
Background: The 2011 GOLD summary report outlines a new COPD grading system based on symptoms, exacerbation history and FEV1. Here we use the COPDGene patient cohort to better understand how well this grading system describes a large, general COPD cohort.
Methods: All COPD subjects from the 10,000 subject COPDGene cohort were grouped per the GOLD 2011 grading system: “A” MMRC ≤1, FEV1 ≥50% and ≤1 exacerbation in the prior year; “B” MMRC ≥2, FEV1≥50% and ≤ 1 exacerbation; “C” MMRC ≤1, FEV1<50% and ≥2 exacerbations; and “D” MMRC ≥2, FEV1<50% and ≥2 exacerbations. Per guidelines, subjects not meeting these criteria were classified as C or D based on MMRC and the worse of FEV1 or exacerbation history categories.
Results: Of 4,475 subjects, 33.8%, 20.9%, 8.3% and 41.0% were classified as GOLD A, B, C and D respectively. FEV1 was lowest (37.1%), BODE index highest (4.7), SGRQ highest (54.0) and walk distance lowest (960 ft) in grade D. Grade D subjects were most frequently on a recommended medication regimen (93.1%), followed by C (68.1%), B (61.0%) and A (24.2%). As grades C and D are defined by MMRC, ≤1 and ≥2 respectively, and either FEV1<50 or ≥2 exacerbations in the prior year, significant heterogeneity in disease severity range is seen: FEV1%, C (18-103) and D (9-103); exacerbations in prior year, C (0-6) and D (0-6); SGRQ C (0-83) and D (2-98); and emphysema C (0.1-52.3%) and D (0.02-61.2%).
Conclusions: A relatively small proportion of subjects met criteria for grade C suggesting patients with low FEV1 and frequent exacerbations but mild dyspnea are less common. While subjects within grades C and D have similar dyspnea severity, they are quite dissimilar with respect to other markers of disease severity.
- © 2012 ERS
