With all this information, participants in the development of the GOLD guidelines determined that although FEV1 is still a good descriptor of COPD severity and potential for poor outcomes (exacerbation frequency, mortality), a more comprehensive description of COPD needed the addition of data on the impact of symptoms (particularly dyspnea), and the future risk of poor COPD related events (exacerbations, death, disease progression). 5 Hence, in response to Dr. B.’s question, it seems that a new approach to the way that we classify COPD was overdue, making it important to gather additional patient information, beyond FEV 1.
GOLD Category Classification
An important difference from previous classifications is that the new GOLD categories use lettered groups, from A to D, not just grades of severity; however, the severity of the ventilatory defect measured by FEV1 is still graded from 1 to 4 and is still part of the classification.9
Placing a patient in the new groups is based on 2 questions: (1) How severe are the symptoms, particularly dyspnea; and (2) Is the patient at high or low risk of poor COPD-related outcomes? The first question (symptoms severity) can be systematically approached using 1 of 2 different instruments to grade COPD symptoms: the modified Medical Research Council dyspnea score (mMRC) or the COPD Assessment Test (CAT), a more recently developed instrument to quantify COPD impact.10,11
Use of CAT score, a more comprehensive descriptor of COPD impact, is the preferred method by guideline developers. If the practitioner is more familiar with the mMRC and wishes to use it instead, the result can be simplified as low (0-1 points) or high symptoms burden (≥ 2 points). The mMRC is based on the answer to the level of effort triggering dyspnea: a score of 1 means that the patient “get[s] shorter of breath when hurrying on a level surface or walking up a slight hill”; a score of 2 means that the patient “walk[s] slower than people of the same age while walking on a level surface because of breathlessness, or I have to stop for breath when walking on my own pace on the level.” Hence, the first step to classify a patient can be as simple as asking about dyspnea, surely part of the history taking process.
The second question (risk of poor COPD-related outcomes) can be answered by using the grade of obstruction by FEV 1 or asking about the frequency of exacerbations in the previous year. If FEV1 is used, those with FEV 1 percentage predicted ≥ 50% are considered as “low risk”; if the airflow obstruction is more severe (previously grades 3-4), the patient is at “high risk” of future events. If the exacerbation frequency is used, ≤ 1 outpatient-treated exacerbation in the previous year qualify as “low,” and ≥ 2 as “high risk.” There is an additional alternative way to identify high risk: all patients with any (≥ 1 per year) exacerbation requiring hospital admission are considered at high risk.
The next step is combining both symptoms and risk to create 4 mutually exclusive groups, which will be relevant to select the appropriate treatment (Table 1). The groups can also be represented graphically using a 2x2 figure, with the horizontal axis being symptoms severity, and the vertical (risk) either FEV1 or exacerbation history (Figure 1). If there is a discrepancy between the risk judged by lung function and history of exacerbations, it is recommended to use the answer corresponding to the worse category. 12