What is the impact of different spirometric criteria on the prevalence of spirometrically defined COPD and its comorbidities? Results from the population-based KORA study
Received 19 January 2016
Accepted for publication 31 March 2016
Published 16 August 2016 Volume 2016:11(1) Pages 1881—1894
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Professor Hsiao-Chi Chuang
Peer reviewer comments 2
Editor who approved publication: Dr Richard Russell
Stefan Karrasch,1–3 Irene Brüske,1 Maia P Smith,1 Barbara Thorand,4 Cornelia Huth,4,5 Karl-Heinz Ladwig,4 Florian Kronenberg,6 Joachim Heinrich,1,7 Rolf Holle,8 Annette Peters,4 Holger Schulz1,7
1Institute of Epidemiology I, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, 2Institute and Outpatient Clinic for Occupational, Social and Environmental Medicine, Ludwig-Maximilians-Universität, 3Institute of General Practice, University Hospital Klinikum rechts der Isar, Technische Universität München, Munich, 4Institute of Epidemiology II, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, 5German Center for Diabetes Research (DZD), Munich/Neuherberg, Germany; 6Division of Genetic Epidemiology, Department of Medical Genetics, Molecular and Clinical Pharmacology, Medical University of Innsbruck, Innsbruck, Austria; 7Comprehensive Pneumology Center Munich (CPC-M), Member of the German Center for Lung Research, 8Institute of Health Economics and Health Care Management, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
Background: There is an ongoing debate about the appropriate spirometric criterion for airway obstruction to detect COPD. Furthermore, the association of different criteria with comorbidity prevalence and inflammatory biomarkers in advanced age is unclear.
Materials and methods: Spirometry was performed in a population-based study (n=2,256) covering an age range of 41–90 years. COPD was spirometrically determined either by a fixed ratio (FR) of <0.7 for forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) or by FEV1/FVC below the lower limit of normal (LLN). Comorbidity prevalences and circulating biomarker levels (C-reactive protein [CRP], interleukin [IL]-6) were compared between subjects with or without COPD by the two criteria using logistic and multiple regression models, adjusting for sex and age.
Results: The prevalence of spirometrically defined COPD by FR increased with age from 10% in subjects aged <65 years to 26% in subjects aged ≥75 years. For LLN-defined COPD, it remained below 10% for all age groups. Overall, COPD diagnosis was not associated with specific comorbidities, except for a lower prevalence of obesity in both FR- and LLN-defined cases. Both CRP and IL-6 tended to be higher in cases by both criteria.
Conclusion: In a population-based cohort of adults up to the age of 90 years, the prevalence of spirometrically defined COPD was higher for the FR criterion than for the LLN criterion. This difference increased with age. Neither prevalences of common comorbidities nor levels of the biomarkers, CRP or IL-6, were conclusively associated with the selection of the COPD criterion. Results have to be considered in light of the predominantly mild cases of airway obstruction in the examined study population.
Keywords: chronic obstructive pulmonary disease, spirometry, prevalence, comorbidity, biomarkers
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