FAQs about the GOLD 2011 assessment proposal of COPD: a comparative analysis of four different cohorts.

Since the publication of the new Global Initiative for Chronic Obstructive Lung Disease (GOLD) proposal for the assessment of chronic obstructive lung disease (COPD), four studies have used existing cohorts to explore the characteristics, temporal variability and/or relationship with outcomes of the four resulting patient categories (A, B, C and D). Here, we compare their results and address a number of frequently asked questions (FAQs) on the topic. The most salient findings were that: 1) the prevalence of these four groups depends on the specific population studied, C being the least prevalent; 2) comorbidities are particularly prevalent in the two "high-symptom" groups (B and D); 3) patients classifiedZ as A or D tend to remain in the same group over time, whereas those classified as B or C change substantially during follow-up; 4) mortality at 3 years was lowest in A and worst in D but surprisingly similar (and intermediate) in B and C; and 5) the incidence of exacerbations during follow-up increases progressively from A to D but that of hospitalisations behave similarly to mortality. These results identify several strengths and shortcomings of the new GOLD assessment proposal, particularly that group B is associated with more morbidity and high mortality.