Clinical relevance of fixed ratio vs lower limit of normal of FEV1/FVC in COPD: patient-reported outcomes from the CanCOLD cohort.

The way in which spirometry is interpreted can lead to misdiagnosis of chronic obstructive pulmonary disease (COPD) resulting in inappropriate treatment. We compared the clinical relevance of 2 criteria for defining a low ratio of forced expiratory volume in 1 second to forced vital capacity (FEV1/FVC): the fixed ratio and the lower limit of normal. We analyzed data from the cross-sectional phase of the population-based Canadian Cohort of Obstructive Lung Disease (CanCOLD) study. We determined associations of the spirometric criteria for airflow limitation with patient-reported adverse outcomes, including respiratory symptoms, disability, health status, exacerbations, and cardiovascular disease. Sensitivity analyses were used to explore the impact of age and severity of airflow limitation on these associations. We analyzed data from 4,882 patients aged 40 years and older. The prevalence of airflow limitation was 17% by fixed ratio and 11% by lower limit of normal. Patients classified as having airflow limitation by fixed ratio only had generally small, nonsignificant increases in the odds of adverse outcomes. Patients having airflow limitation based on both fixed ratio and lower limit of normal had larger, significant increases in odds. But strongest associations were seen for patients who had airflow limitation by both fixed ratio and lower limit of normal and also had a low FEV1, defined as one less than 80% of the predicted value. Our results suggest that use of the fixed ratio alone may lead to misdiagnosis of COPD. A diagnosis established by both a low FEV1/FVC (according to fixed ratio and/or lower limit of normal) and a low FEV1 is strongly associated with clinical outcomes. Guidelines should be reconsidered to require both spirometry abnormalities so as to reduce overdiagnosis of COPD.

van Dijk W ，Tan W ，Li P ，Guo B ，Li S ，Benedetti A ，Bourbeau J ，CanCOLD Study Group ... -  《-》

Misidentification of airflow obstruction: prevalence and clinical significance in an epidemiological study.

Pothirat C ，Chaiwong W ，Phetsuk N ，Liwsrisakun C ... -  《International Journal of Chronic Obstructive Pulmonary Disease》

Cut-off value of FEV1/FEV6 as a surrogate for FEV1/FVC for detecting airway obstruction in a Korean population.

Chung KS ，Jung JY ，Park MS ，Kim YS ，Kim SK ，Chang J ，Song JH ... -  《International Journal of Chronic Obstructive Pulmonary Disease》

COPD in chronic heart failure: less common than previously thought?

Using a fixed ratio of forced expiratory volume in 1 s to forced vital capacity (FEV1/FVC) < 0.70 instead of the lower limit of normal (LLN) to define chronic obstructive pulmonary disease (COPD) may lead to overdiagnosis of COPD in elderly patients with heart failure (HF) and consequently unnecessary treatment with possible adverse health effects. The aim of this study was to determine COPD prevalence in patients with chronic HF according to two definitions of airflow obstruction. Spirometry was performed in 187 outpatients with stable chronic HF without pulmonary congestion who had a left ventricular ejection fraction <40% (mean age 69 ± 10 years, 78% men). COPD diagnosis was confirmed 3 months after standard treatment with tiotropium in newly diagnosed COPD patients. COPD prevalence varied substantially between 19.8% (LLN-COPD) and 32.1% (GOLD-COPD). Twenty-three of 60 patients (38.3%) with GOLD-COPD were potentially misclassified as having COPD (FEV1/FVC < 0.7 but > LLN). In contrast to patients with LLN-COPD, potentially misclassified patients did not differ significantly from those without COPD regarding respiratory symptoms and risk factors for COPD. One fifth, rather than one third, of the patients with chronic HF had concomitant COPD using the LLN instead of the fixed ratio. LLN may identify clinically more important COPD than a fixed ratio of 0.7.

Minasian AG ，van den Elshout FJ ，Dekhuijzen PN ，Vos PJ ，Willems FF ，van den Bergh PJ ，Heijdra YF ... -  《-》

Vital capacity and COPD: the Swedish CArdioPulmonary bioImage Study (SCAPIS).

Torén K ，Olin AC ，Lindberg A ，Vikgren J ，Schiöler L ，Brandberg J ，Johnsson Å ，Engström G ，Persson HL ，Sköld M ，Hedner J ，Lindberg E ，Malinovschi A ，Piitulainen E ，Wollmer P ，Rosengren A ，Janson C ，Blomberg A ，Bergström G ... -  《International Journal of Chronic Obstructive Pulmonary Disease》