Pulmonary Disorders: COPD

Assessment of and Functional Classification of COPD

GOLD diagnostic criteria include the following:

• Presence of symptoms (see Table 1 in Appendix A)
• FEV1/FVC ratio of <0.70 following short-acting beta agonist
• Exclusion of other diagnoses (e.g., alpha-1 antitrypsin deficiency, cardiac disorders, and others)

For persons meeting the diagnostic criteria, GOLD classifies patients in two phases for purposes of guiding treatment. The initial phase is by severity of airflow obstruction determined by spirometry. The second phase involves matching frequency and severity of prior exacerbations with assessment of the adverse effect of the COPD on the individual’s life. This second phase results in a grid crossing two degrees of each of the categorization criteria.

Assessment of Airflow Limitation
GOLD criteria for staging severity of COPD use spirometry results with a score from 1 to 4 defined by the FEV1 (see Table 3). This spirometry should be performed following administration of a short-acting beta agonist to assess maximal obtainable results.

Table 3. GOLD COPD Airflow Restriction Categorization

*With FEV1/FVC <0.70

Assessment of Symptom Burden
GOLD recommends standardized questionnaires for symptom burden assessment. The Modified Medical Research Council (mMRC) Questionnaire (see Table 4) has been selected by GOLD due to simplicity of application and global distribution despite relying solely on degree of breathlessness. It also correlates well to several general health status questionnaires.11 GOLD has chosen the 10-element COPD Assessment Test (CAT™) as a questionnaire that does query a wider aspect of a respondent’s life and also correlates well with the 50-element St. George’s Respiratory Questionnaire (SGRQ), considered too complex for routine clinical use. Other validated questionnaire tools and validated functional assessment tools exist. GOLD chose these two questionnaire tools for clinical simplicity and their wide current use.

At least one study has noted variability in classification of a cohort of patients between the mMRC and CAT as well as between the questionnaires with treating physician assessment and patient self-assessment.15 Several validated functional assessment tools also exist; however, they are targeted largely at populations with quite severe life activity impairment.12 The mMRC, developed by the British Medical Research Council and well-validated, assesses only dyspnea on a 5-point scale.

Table 4. mMRC Dyspnea Assessment Scoring

The CAT was developed by a multi-disciplinary group of COPD experts with financial support from GlaxoSmithKline (GSK) with oversight of GSK activities by a governance board that includes external experts, one of whom chairs the board. Although GSK owns the copyright, the test is freely available on the Internet. The CCQ questionnaire is promulgated through the University Medical Centre Groningen, the Netherlands. Though cited by GOLD and other authors it is less widely used in the U.S. than the CAT and will not be further discussed here as GOLD also only discusses the CAT.

The CAT uses a 0-5 scale for answers in 8 domains:

• presence of coughing, “none” to “all the time”
• production of phlegm, “no phlegm” to “my chest is full all the time”
• chest tightness, “not at all” to “feels very tight”
• shortness of breath when walking up a hill or a flight of stairs, “not breathless” to “very breathless”
• limitation of activities at home, “not limited” to “very limited”
• confidence in leaving home in relation to lung condition, “confident despite” to “not at all confident”
• quality of sleep, “soundly” to “don’t sleep soundly due to my lung condition”
• level of energy, “lots” to “no energy at all”

A score of 10 is considered a cut-point for considering instituting treatment based on correlation to the St. George’s Respiratory Questionnaire (SGRQ), considered too complex for routine clinical use.

Assessment of Exacerbation Risk
COPD exacerbations have been defined as changes in clinical status leading to additional therapy that may be simply use of short-acting bronchodilators to hospitalization.3,13 While there have been a number of studies showing that the rate of exacerbations varies greatly among persons with diagnosed COPD, the best predictor of future exacerbations has been determined to be the history of prior exacerbations.

Exacerbations have been categorized into three levels of severity:

• MILD – treated only with SABA
• MODERATE – SABA plus either antibiotics and/or oral steroids
• SEVERE – hospitalization or emergency department visits

GOLD proposes setting the score on the CAT versus the exacerbation risk based on the number and severity of prior exacerbations to determine a secondary classification for treatment guidance expressed in four classifications A, B, C, D.

Overall GOLD Assessment Scheme for COPD
The initial assessment of airflow obstruction on the GOLD scale of 1-4 (mild – severe) is matched with exacerbation risk and symptom burden for a final categorization. Although expressed together, based on research since being proposed, GOLD recognizes in the most recent version (2019) that there may be discordance; that is, persons with more severe airway obstruction, but low symptom burden or the inverse.1

The final GOLD classification is expressed as a combination of a number (1 – 4) for airflow limitation and a letter (A – D) intended to offer a more individualized clinical classification. The classification categories of A – D essentially correlate as follows:

• A: Low risk of exacerbation, less life impairment
• B: Low risk of exacerbation, more life impairment
• C: High risk of exacerbation, less life impairment
• D: High risk of exacerbation, more life impairment

The spirometric classifications do not, necessarily, predict to which letter designation an individual patient will be assigned. The categories are intended to assist with treatment decisions. They are not designed to address assessment of functional capacity even though the combinations of numbers and letters can provide a general concept of adverse effect on a patient’s life functions. As is apparent from the grid, categories A and C represent persons with less significant adverse effect reported on their personal lives as reflected by a lower CAT/mMRC score. There is evidence that persons in category B, though having better lung function, may have poorer long term outcomes (death) than ones classified in category C, supporting the importance of evaluation beyond simply spirometry.14

Overall Assessment for LEO Evaluations
As is apparent from the GOLD classification scheme, there are multiple factors involved in classifying both the physical status and the life effect of COPD. Additionally, at least one study has noted significant disagreement between the 2011 (same strategy as 2017, 2018, and 2019) GOLD classification scheme and severity rating by treating physicians and patients.15

GOLD proposes the additional steps of assessing symptom burden on quality of life and exacerbation history to assist with treatment recommendations/decisions such as choices among long-acting beta-agonists, long-acting muscarinic agents, fixed-dose combinations and other interventions such as lung reduction surgery.

As has been noted, spirometry loses specificity on the individual patient level in terms of predicting functional impairment. However, spirometry, does, as reinforced by the GOLD classification scheme, represent a valid component of a final classification process. For assessing whether LEOs can safely and effectively perform the essential job functions, the use of spirometry deficit as classified by GOLD is, in the opinion of the Task Group, an appropriate initial methodology of assessing severity of the pathophysiological status of COPD.

GOLD 2019 recognizes that there may be discordance between severity of airway obstruction and patient-reported symptom burden (mMRC or CAT scores). GOLD recommends that, if the assessing clinician has a question regarding the validity of the patient’s self-assessment of burden, some form of physical challenge testing should be employed for a more objective assessment of functional status. This approach is particularly relevant for assessing LEOs with COPD for ability to safely and effectively perform essential job functions.

Functional capacity testing protocols validated for clinical use in COPD patients involve a low level of exertion, being designed for patients with quite significant symptom burden, thus making them not applicable for assessing LEOs, more likely to have milder disease. No functional capacity test designed for COPD patients has been validated in LEOs.

For the purposes of determining, as best as is possible with current methodologies, whether an LEO with a diagnosis of COPD can safely and effectively perform essential job functions, the use of a law enforcement specific physical function test offers a parallel logic to clinical assessment. Appendix C addresses functional testing of LEOs with COPD.