Objective: The objective of this study was to examine how COPD patients were classified by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) spirometry-based severity system and the distribution of COPD severity using the new GOLD 2011 assessment framework.
Materials and methods: This was an observational, retrospective cohort study conducted in a single tertiary center on a prospective database, which aimed to evaluate the prevalence, incidence, severity, and comorbidities of COPD. Inclusion criteria were age ≥40 years and COPD diagnosis according to GOLD 2007 classification. Clinical factors were compared between the categories in GOLD 2007 and 2011 groups by using the χ2 test for categorical data and the analysis of variance for continuous data.
Results: In total, 420 COPD patients were included in the analysis. The distribution of patients into GOLD 2007 categories was as follows: 6.4% (n=27) of them were classified into subgroup I, 42.1% (n=177) into subgroup II, 37.9% (n=159) into subgroup III, and 13.6% (n=57) into subgroup IV. The distribution of patients into GOLD 2011 categories was as follows: 16.4% (n=69) of them were classified into subgroup A (low risk and fewer symptoms), 32.1% (n=135) into subgroup B (low risk and more symptoms), 21.6% (n=91) into subgroup C (high risk and fewer symptoms), and 29.7% (n=125) into subgroup D (high risk and more symptoms). After the application of the new GOLD 2011 (modified Medical Research Council [mMRC] system), 22% (n=94) of patients were upgraded to a higher level than their spirometry level, and 16.2% (n=68) of them were downgraded in their severity category, meaning that almost 40% of patients changed their severity assessment category. In total, 22% of patients in stage I were allocated to group B, and 35% of patients in stage IV were allocated to group C. Patients in stage III were the most frequently upgraded to a higher risk group (D), taking into account mMRC and exacerbation history.
Conclusion: Classifying patients using the new GOLD 2011 criteria reallocated a relevant proportion of patients to a different risk category and identified larger proportions of patients in the mildest and more severe groups compared with GOLD 2007 classification.
Keywords: comorbidities; exacerbation; incidence; severity; spirometry level.