Open AccessImpact of diagnostic criteria on the prevalence of COPD
Author(s) -
Çolak Yunus,
Løkke Anders,
Marott Jacob Louis,
Lange Peter,
Vestbo Jørgen
Publication year - 2013
Publication title -
the clinical respiratory journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.789
H-Index - 33
eISSN - 1752-699X
pISSN - 1752-6981
DOI - 10.1111/crj.12007
Subject(s) - medicine , copd , spirometry , asymptomatic , vital capacity , pulmonary disease , confidence interval , epidemiology , lung function , lung , asthma , diffusing capacity
The reduction in the ratio between forced expiratory volume in 1 s ( FEV 1 ) and forced vital capacity ( FVC ) is used for the diagnosis of chronic obstructive pulmonary disease ( COPD ). The choice between a simple fixed cut‐off ratio ( FEV 1 / FVC <0.70) and the use of lower limit of normal ( LLN ) is eagerly discussed. The aim of this paper was to examine the impact of these two diagnostic measures on the prevalence of COPD using data from the fourth examination of T he C openhagen C ity H eart S tudy ( CCHS 4). Materials and Methodology A total of 6237 subjects participated in CCHS 4 from 2001 to 2003. Asymptomatic, healthy never‐smokers of all ages with adequate information from questionnaires and spirometry were used to calculate LLN . Results LLN was declining with increasing age and height. If LLN was used as the correct diagnostic criterion, under‐ and over‐diagnosis among men were 0.4% and 7.0%, respectively, and for women 2.0% and 1.4%, respectively, when using the fixed ratio. Over‐diagnosis among men was reduced from 7.0% to 3.0% by changing the fixed cut‐off ratio to FEV 1 / FVC <0.65 for subjects older than 65 years. Among women, however, this adjustment led to an increase in under‐diagnosis from 2.0% to 5.7%. Most participants with FEV 1 / FVC <0.70 but > LLN had well‐preserved FEV 1 . Conclusion Using the fixed ratio for diagnosing COPD in an epidemiological setting results in a higher prevalence than if the LLN is used. Time seems ripe for studying if the same is seen when diagnosing COPD in the clinical setting.