Abstract
The GOLD 2020 updates added more lucidity on the treatment of COPD. However, few diagnostic dilemmas still exist. Research is needed on the use of the CAT score in assessing symptoms for the diagnosis of COPD. Further work-up is needed on diagnostic instability of spirometry, and diagnostic role of the lower limit of normal (LLN) criteria, slow vital capacity (FEV1/VC), forced inspiratory vital capacity (FEV1/FIVC), and rapid FEV1 decline. Incorporating parameters of lung hyperinflation and exercise capacity in the COPD diagnostic criteria might add value in its diagnosis and management. GOLD’s approach towards routine CT imaging needs to be reviewed. Establishing a “pre-COPD” stage can be helpful in the early diagnosis and intervention to reduce the rapid lung function decline among at-risk individuals. The use of mMRC score as a surrogate to assess the overall severity of COPD related symptoms should be reviewed. The therapeutic guidance role of sputum eosinophils should be studied in patients with intermediate and low blood eosinophil counts.
| Abbreviations | ||
| CAT | = | COPD assessment test |
| COPD | = | Chronic obstructive pulmonary disease |
| DLCO | = | diffusing capacity of the lung for carbon monoxide |
| EELV | = | end expiratory lung volume |
| FEV1 | = | forced expiratory volume in one second |
| FIVC | = | forced inspiratory vital capacity |
| FVC | = | forced vital capacity |
| GOLD | = | global initiative for chronic obstructive lung disease |
| IC | = | inspiratory capacity |
| ICS | = | inhaled corticosteroids |
| LABA | = | long acting beta agonists |
| LAMA | = | long acting muscarinic antagonists |
| LLN | = | lower limit of normal |
| mMRC | = | modified medical research council |
| PROs | = | patient related outcomes |
| RV | = | residual volume |
| TLC | = | total lung capacity |
| VC | = | vital capacity |
Commentary
Since its first report on chronic obstructive pulmonary disease (COPD) management in 2001, the global initiative for chronic obstructive lung disease (GOLD) recommendations have evolved substantially. The last major revision in 2017 and the recently released 2020 update [Citation1] have indeed paved the way to accomplish its four vital goals - raising awareness, improving quality of management, stimulating research, and providing evidence-based educational resources. Though the recent updates added more lucidity on the treatment of COPD, a few diagnostic dilemmas still exist.
The current operational definition and diagnostic approach based on symptoms and spirometry may not be adequate for a heterogeneous disease with an under-diagnosis rate as high as 90% [Citation2], and which might therefore lead to misdiagnosis of COPD and individuals at risk of disease. Research is needed on the efficacy of comprehensive questionnaires like the COPD assessment test (CAT) in the diagnosis of COPD instead of the current over-reliance on the subjective perception of a few respiratory symptoms.
GOLD efforts on promoting spirometry not only as a case-finding and prognostication tool for airflow obstruction but also as a marker for good health are commendable. Though there is ample evidence on the early-life origins of COPD [Citation3,Citation4], and significant global prevalence of early-COPD (COPD in <50 years of age) 4–6% [Citation5], the current GOLD spirometry criteria appear to be aimed mainly at well-established disease in older individuals. Due to its simplicity and superiority in estimating the prognosis in the population aged 45 years and older [Citation6], GOLD continued recommending the fixed ratio (FEV1/FVC <0.7) for diagnosis, which might be underdiagnosing airflow obstruction in the younger population. One of the ambiguous areas in the GOLD 2018 update was the recommendation for repeat spirometry for the individuals presenting with the FEV1/FVC ratio between 0.6 to 0.8 due to diagnostic instability [Citation7]. Further work-up is needed to observe the ideal interval for repeat spirometry, the duration for such follow-up and strategies for interpretation. Research is also required on defining COPD using the lower limit of normal (LLN) criteria, slow vital capacity (FEV1/VC), forced inspiratory vital capacity (FEV1/FIVC), and rapid FEV1 decline in conjunction with symptoms and risk factors.
We further suggest that incorporating lung volumes, especially parameters of hyperinflation (TLC, IC, EELV, RV, and RV/TLC), diffusion capacity (DLCO) and diminished exercise capacity in diagnostic criteria might add value as they are independently associated with exacerbations and/or mortality in COPD patients [Citation8,Citation9]. Regardless of the well-known consequences of static and dynamic hyperinflation, these anomalies have not been included in the diagnosis nor management of COPD. Lung volume estimation by CT imaging can also predict the progression to COPD in smokers with normal spirometry [Citation10]. Despite acknowledging the diagnostic, phenotypic, and prognostic values of CT scanning in COPD, GOLD’s approach in not recommending routine CT imaging requires further review.
Early diagnosis and intervention to reduce the rapid lung function decline among at-risk individuals is vital in addressing future morbidity and mortality in COPD. Consequently, we need to recognise a stage of increased risk, “pre-COPD”, as has been done for other non-communicable diseases such as diabetes and hypertension. Unfortunately, the earlier GOLD recommendations prematurely abandoned such an entity (GOLD stage 0) based on the evidence from the post-hoc analysis of the Copenhagen city heart study in which pre-COPD was based solely on the presence of a single symptom of cough among smokers with normal FEV1/FVC ratio [Citation11]. Research is therefore required to define pre-COPD precisely by considering the presence of various respiratory and constitutional symptoms; early pulmonary functional limitations such as isolated increase of residual volume, diminished diffusion capacity and accelerated decline in FEV1; and anatomical changes such as airway abnormalities, emphysema and vascular changes.
In the latest update, the multimodal “ABCD” approach to commence COPD treatment is more logical. Nevertheless, using the mMRC breathlessness scale as a surrogate to assess the overall severity of COPD related symptoms may not be ideal. Replacing it with a well-validated questionnaire like the CAT, which covers the broad range of symptoms like cough, chest tightness, activity limitation, sleep and energy levels, is more appropriate.
The new peripheral eosinophil count-based treatment is an insightful and welcomed approach. Though sputum eosinophils are superior to peripheral eosinophils in identifying the severe COPD and frequent exacerbators [Citation12], their cost and limited availability impacts broader use in the real world. However, studying their therapeutic guidance role in patients with intermediate and low blood eosinophil counts (≤300 cells/μL) can yield more precise therapeutic approaches. Selective use of inhaled steroid preparations to avoid adverse effects like pneumonia in severe COPD warrant head-to-head comparative studies. Also, strategies for de-escalation of inhaled steroid therapy are needed.
In spite of having ample evidence on the efficacy of dual bronchodilatation (LAMA + LABA) in symptom, functional and patient-related outcomes (PROs) improvement [Citation13–15]; and combination inhaler therapy (LABA + ICS) in prevention of exacerbations [Citation16,Citation17], GOLD’s current circumspect approach of recommending single bronchodilator treatment as the initial choice for the groups B and C should be considered for revision. In the real-world scenario, choosing the step-down therapeutic approach might be more sensible than the step-up method. Adaptive platform trials are required in the future to address the current treatment uncertainties in the management of COPD. Also, more evidence is needed to advocate the need and modalities of screening for comorbidities, complications and overlap syndromes such as pulmonary hypertension, lung cancer, bronchiectasis, anxiety and depression.
Though GOLD emphasises its recommendations as not strictly guidelines, over the last two decades, they have earned a wide global healthcare professional following. GOLD’s current approach in diagnosing this complex disease appears simplistic and can defeat the purpose of its own visionary goals. Any new opportunities to improve the care of one of the leading causes of global mortality should not be missed.
Declaration of interest
The authors have no conflicts of interest to declare.
Funding
There was no source of funding for this article
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