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      Letter to the Editor, International Journal of COPD [Letter]

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          Dear editor We read the paper by Llordés et al1 with some interest. The results from this small study are interesting but the analysis and conclusion seem to be at odds with the data. The authors consider a COPD diagnosis by both lower limit of normal (LLN) and the fixed ratio (FR), that is FEV1/FVC<0.7, as concordant (LLN+FR+) and subjects who are FR+LLN- as discordant. Their data show that the discordant group have lower CAT score and lower BODE index suggesting that this group likely has other co-morbidities. As expected, the discordant group is older, more male-dominated2 and has fewer hospital admissions. Furthermore, the discordant group has a better overall survival and less respiratory mortality which highlights that the discordant group is quite dissimilar to the concordant group. It is not clear how these data clearly demonstrate that using the FR in the diagnosis COPD is superior to LLN. The single piece of data the authors have to support their main conclusion, that the FR is better for diagnosing COPD than the LLN, is that the discordant group has a greater decline in FEV1/FVC than the concordant group. This is not an acceptable way to look at deterioration of airflow obstruction.3 In patients with a low FEV1/FVC the ratio can increase with severity since the FVC starts to reduce to a greater extent because of premature airway closure. Decline in FEV1 should be used to assess deterioration, and no significant difference in annualised decline in FEV1 was shown. The authors strong conclusion that LLN is less useful than FR for diagnosing COPD in primary care seems to be a misinterpretation of the data presented.

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          Fixed Ratio versus Lower Limit of Normality for Diagnosing COPD in Primary Care: Long-Term Follow-Up of EGARPOC Study

          Purpose The best criterion for diagnosing airway obstruction in COPD, fixed ratio (FR: FEV1/FVC<0.7) or lower limit of normality (LLN), remains controversial. We compared the long-term evolution of COPD patients according to the initial obstruction criteria. Patients and Methods Between 2005 and 2008, we evaluated 1728 subjects over 45 years of age with smoking history, pertaining to a primary care center. A total of 424 patients were obstructive by FR, after a bronchodilator test. Of those, 289 patients met obstruction criteria for both FR and LLN and were considered concordant patients (FR+LLN+), while 135 patients were obstructive by FR but non-obstructive by LLN and were defined as discordant patients (FR+LLN-). Results Forty-eight patients (11.3%) were lost in follow-up, and 158 died (37.3%). After a median time of 120.4 months (IQR 25–75%: 110.2–128.8), 215 patients were spirometrically reevaluated. The annualized loss of FEV1/FVC was greater in discordant (FR+LLN-) patients [0.54 (0.8) vs 0.82 (0.7); p = 0.008], while 81% became concordant (FR+LLN+) during the follow-up. Hospitalization for COPD exacerbations was more frequent in concordant (FR+LLN+) patients (1.57±3.51 vs 0.77±2.29; p = 0.002). Adjusting for age, concordant (FR+LLN+) patients had greater COPD mortality (HR: 2.97; CI 95%: 1.27–7.3; p = 0.02). Conclusion LLN seems to be less useful for COPD diagnosis in primary care. Discordant (FR+LLN-) patients lost more FEV1/FVC during their evolution and tended to become concordant. LLN predicted COPD hospitalizations and mortality more poorly.
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            Chronic obstructive pulmonary disease: missed diagnosis versus misdiagnosis.


              Author and article information

              Int J Chron Obstruct Pulmon Dis
              International Journal of Chronic Obstructive Pulmonary Disease
              28 September 2020
              : 15
              : 2307-2308
              [1 ]Institute of Applied Health Sciences, University of Birmingham , Birmingham, UK
              [2 ]Lung Function and Sleep, Queen Elizabeth Hospital , Birmingham, UK
              [3 ]Community Health and Epidemiology, Dalhousie University , Halifax, NS, Canada
              Author notes
              Correspondence: Brendan G Cooper Lung Function and Sleep, Queen Elizabeth Hospital Birmingham , Mindelsohn Way, Edgbaston, BirminghamB15 2GW, UKTel +44 121 371 3890 Email
              © 2020 Miller et al.

              This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at and incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License ( By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms (

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              Respiratory medicine


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