Diagnosing chronic obstructive pulmonary disease
BMJ 2015; 351 doi: https://doi.org/10.1136/bmj.h6171 (Published 24 November 2015) Cite this as: BMJ 2015;351:h6171
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To the Editor
Diagnosing chronic obstructive pulmonary disease
We read with interest the paper by Conway and colleagues (1). Although we appreciate the effort to simplify the clinical approach to chronic obstructive pulmonary disease (COPD), we feel this raises serious concerns with the diagnosis of the disease made in primary care. Following the GOLD recommendations (2) the Authors suggest to use the FEV1/FVC ratio <0.70 as the lung function index to confirm the diagnosis of COPD, disregarding the fact that such a criterion has been the object of intensive debate since it was first proposed by the GOLD committee, because it was grounded more on opinions than scientific rationale (3). As well known from lung physiology, the ratio FEV1/FVC normally decreases with aging so that it naturally falls below the proposed threshold of 0.70 at about between the 5th and 6th decade of life depending on sex. Therefore, if one accepts this ratio as a proof of airflow obstruction, then people with no or only modest risk factors could be misdiagnosed as COPD simply because they are aging, with the ensuing risk of being inappropriately treated. This problem has been recently brought to the attention of general practitioners in an article published in this same journal by Miller and Levy (4), emphasizing the remarkable medical consequences of COPD misdiagnosis, ranging from harming the patient with unnecessary therapies that have side effects to wasting public money.
Also following the GOLD recommendations, Conway and colleagues (1) suggest that severity of the disease be estimated from percent of predicted values at fixed thresholds, without any word of caution that these were arbitrarily chosen without validation by patient-centered outcomes. In two recent studies, Vaz Fragoso and colleagues (4, 5) showed that using fixed thresholds for FEV1/FVC and FEV1 % of predicted leads not only to misdiagnosis but also to severity misclassification in a number of patients, which can be avoided if thresholds based on the frequency distribution of lung function indices are used. Finally, we would like to underline that simple spirometry alone does not provide sufficient information on the complexity of COPD. At presentation a complete functional evaluation including measurements of lung volumes and diffusing capacity is desirable to help phenotype individual patients.
In conclusion, there is abundant evidence that arbitrary, albeit simple, thresholds of natural variability and severity do not correctly reflect the conditions on which diagnosis and treatment of COPD should be based. This evidence cannot be ignored when carrying out our daily clinical practice. In an era of computers there is no need to remember simple numbers and, as for other age-related medical disorders such as osteoporosis, the limits of natural variability based on confidence intervals from a suitable reference population (7, 8) should be used for diagnosing COPD. We cannot let the management of this complex disease be crippled into the future by sticking with erroneous past dogma.
Vito Brusasco1, Riccardo Pellegrino2, Martin R. Miller3
1 Dipartimento di Medicina Interna e Specialità Mediche, Università di Genova, Genoa, Italy.
2 Centro Medico Pneumologico Torino, Turin, Italy.
3 Institute of Occupational and Environmental Medicine, University of Birmingham, UK.
References
1. Conway F, Majeed A, Easton G. Diagnosing chronic obstructive pulmonary disease. BMJ 2015; 351:h6171 doi: 10.1136/bmj.h3171.
2. Global Initiative for Chronic Obstructive Lung Disease (GOLD). Global strategy for the diagnosis, management, aad prevention of chronic obstructive pulmonary disease. Updated 2015. www.goldcopd.org/guidelines-global-strategy-for-diagnosis-managent.html.
3. Quanjer PH, Ruppel G, Brusasco V, Pérez-Padilla R, Fragoso CA, Culver BH, Swanney MP, Miller MR, Thompson B, Morgan M, Hughes M, Graham BL,Pellegrino R, Enright P, Buist AS, Burney P. COPD (confusion over proper diagnosis) in the zone of maximum uncertainty. Eur Respir J. 2015; 46: 1523-1524.
4. Miller MR, Levy ML. Chronic obstructive pulmonary disease: missed diagnosis versus misdiagnosis. BMJ. 2015;351:h3021.
5. Vaz Fragoso CA, Mc Avay G, Van Ness PH, Casaburi R, Jensen RL, MacIntyre N, Gill TM, Yaggi HK, Concato J. Phenotype of normal spirometry in an aging population. Am J Respir Crit Care Med 2015; 192; 817-825.
6. Vaz Fragoso CA, Mc Avay G, Van Ness PH, Casaburi R, Jensen RL, MacIntyre N, Yaggi HK, Gill TM, Concato J. Phenotype of spirometric impairment in an aging population. Am J Respir Crit Care Med First published online 5 Nov 2015 as DOI: 10.1164/rccm.201508-1603OC.
7. Pellegrino R, Viegi G, Brusasco V, Crapo RO, Burgos F, Casaburi R, Coates A, van der Grinten CP, Gustafsson P, Hankinson J, Jensen R, Johnson DC, MacIntyre N, McKay R, Miller MR, Navajas D, Pedersen OF, Wanger J. Interpretative strategies for lung function tests. Eur Respir J 2005; 26: 948-968.
8. Quanjer PH, Stanojevic S, Cole TJ, Baur X, Hall GL, Culver BH, Enright PL, Hankinson JL, Ip MS, Zheng J, Stocks J; ERS Global Lung Function Initiative. Multi-ethnic reference values for spirometry for the 3-95-yr age range; the global lung function 2012 equations. Eur Respir J 2012; 40: 1324-1343.
Competing interests: No competing interests
To the editor
Diagnosing chronic obstructive pulmonary disease
In a recent study Conway et al. [1] delineate how to establish a diagnosis of chronic obstructive pulmonary disease (COPD) in primary care. This is an important topic because of the relatively high prevalence and incidence of COPD in an ageing population, and the authors correctly point out that establishing a diagnosis requires confirmation by a low FEV1/FVC ratio. They state that a ratio <0.70 confirms a diagnosis of pathological airflow limitation. The GOLD group [2] recommended such a cut-off point in 2001 without validation, because it was thought that it would often be too complicated to calculate the proper lower limit of normal (LLN), which declines with age well beyond the fixed ratio of 0.7. However, nowadays the LLN is included in output from all spirometry equipment, obviating the need for a simple rule of thumb. There is extensive literature documenting that the use of the fixed ratio leads to underestimating the prevalence of airways obstruction in subjects younger than 45 years and extensive age-dependent overestimation above that age, with up to 75–80% false positive rates in 80-year-old healthy subjects [3]. There is overwhelming evidence that an FEV1/FVC ratio <0.7 but above the LLN does not represent clinical relevant respiratory disease.
Whereas fixed-ratio airflow limitation in individuals classified by LLN as non-obstructive is associated with heart disease rather than clinically significant airways obstruction [4], it is not associated with an abnormal decline in FEV1 [5-7], respiratory care use [5], hos¬pi¬talisation [8], premature death [8-12] or quality of life [5]. However, an FEV1/FVC ratio below the LLN is associated with increased risk of hospitalisation [8] and mortality [6-8,11-13].
We therefore recommend that spirometric confirmation of a diagnosis of airways obstruction is based on symptoms and an FEV1/FVC ratio below the LLN, in keeping with recommendations by American Thoracic Society and European Respiratory Society [14].
Philip H. Quanjer1, Irene Steenbruggen2, Jan Willem van den Berg2
1 Dept of Pulmonary Diseases and Department of Paediatrics–Pulmonary Diseases, Erasmus Medical Centre, Erasmus University, Rotterdam, The Netherlands.
2 Dept of Pulmonary Diseases, Isala, Zwolle, The Netherlands
1. Conway F, Majeed A, Easton G. Diagnosing chronic obstructive pulmonary disease. BMJ 2015; 351: h6171.
2. Pauwels RA, Buist AS, Calverley PMA, et al. Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease: NHLBI/WHO Global Initiative for Chronic Obstructive Lung Disease (GOLD) Workshop summary. Am J Respir Crit Care Med 2001; 163: 1256–1276.
3. Quanjer PH, Stanojevic S, Cole TJ, et al. Multi-ethnic reference values for spirometry for the 3–95-yr age range: the global lung function 2012 equations. Eur Respir J 2012; 40: 1324–1343.
4. Lamprecht B, Schirnhofer L, Kaiser B, Buist SA, Mannino DM, Studnicka M. Subjects with discordant airways obstruction: Lost between spirometric definitions of COPD. Pulm Med 2011; 780215.
5. Bridevaux P-O, Gerbase MW, Probst-Hensch NM, et al. Long-term decline in lung function, utilisation of care and quality of life in modified GOLD stage 1 COPD. Thorax 2008; 63: 768–774.
6. Akkermans RP, Berrevoets MA, Smeele IJ, et al. Lung function decline in relation to diagnostic criteria for airflow obstruction in respiratory symptomatic subjects. BMC Pulm Med 2012; 12: 12.
7. Akkermans RP, Biermans M, Robberts B, et al. COPD prognosis in relation to diagnostic criteria for airflow obstruction in smokers. Eur Respir J 2014; 43: 54–63.
8. Turkeshi E, Vaes B, Andreeva E, et al. Airflow limitation by the Global Lungs Initiative equations in a cohort of very old adults. Eur Respir J 2015; 46: 123–132.
9. Mannino DM, Doherty DE, Buist AS. Global Initiative on Obstructive Lung Disease (GOLD) classifi-cation of lung disease and mortality: findings from the Atherosclerosis Risk in Communities (ARIC) study. Respir Med 2006; 100: 115–122.
10. Ekberg-Aronsson M, Pehrsson K, Nilsson JA, et al. Mortality in GOLD stages of COPD and its dependence on symptoms of chronic bronchitis. Respir Res 2005; 6: 98.
11. Vaz Fragoso CA, Concato J, McAvay G, et al. Chronic obstructive pulmonary disease in older persons: a comparison of two spirometric definitions. Respir Med 2010; 104: 1189–1196.
12. Mannino DM, Buist AS, Vollmer WM. Chronic obstructive pulmonary disease in the older adult: what defines abnormal lung function? Thorax 2007; 62: 237–241.
13. Luoto JA, Elmstahl S, Wollmer P, Pihlsgard M. Incidence of airflow limitation in subjects 65-100 years of age. Eur Respir J 2015. doi: 10.1183/13993003.00635-2015.
14. Pellegrino R, Viegi G, Brusasco V, et al. Interpretative strategies for lung function tests. Eur Respir J 2005; 26: 948–968.
Competing interests: No competing interests
Re: Diagnosing chronic obstructive pulmonary disease
We thank Professor Brusasco and Professor Quanjer for their comments on our article.[1] In their responses to our article, they raise the possibility that current NICE guidelines on the management of COPD may lead to over-diagnosis in older people and under-diagnosis in younger people because of age-related changes in lung function.
Although this is possible, it is also the case that the use of a measure of lung function such as Lower Limit of Normal (LLN) rather than a FEV1/FVC ratio < 0.7 could lead to under-diagnosis in some groups.[2] All measures of lung function have limitations in terms of their accuracy, ease of use in clinical practice and cost-effectiveness when used to diagnose COPD. NICE is due to review its COPD guidance in 2016 and in this review, it will need to systematically evaluate data from studies that have assessed the accuracy of measures of lung function in the diagnosis of COPD. Without seeing the results of such a systematic review, it is not possible to state categorically that a fixed FEV1/FVC ratio; a ratio adjusted for age, sex and height; or some other measure of lung function should be used to make the diagnosis of COPD.
Although there was not space to go into the details of this important debate in an article like this, we are grateful for them raising the issue. Whatever diagnostic criteria are used to diagnose COPD, it is important that patients with COPD do receive an accurate diagnosis so that they can benefit from treatment, and the current gap between predicted and diagnosed prevalence is narrowed.[3]
References
1. Conway F, Majeed A, Easton G. Diagnosing chronic obstructive pulmonary disease. BMJ 2015; 351:h6171
2. Güder G, Brenner S, Angermann CE et al. GOLD or lower limit of normal definition? a comparison with expert-based diagnosis of chronic obstructive pulmonary disease in a prospective cohort-study. Respir Res. 2012; 13(1): 13.
3. Nacul L, Soljak M, Samarasundera E. COPD in England: a comparison of expected, model-based prevalence and observed prevalence from general practice data. J Public Health 2011;33:108-16.
Competing interests: No competing interests