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Underestimation of airflow obstruction among young adults using FEV1/FVC <70% as a fixed cut-off: A longitudinal evaluation of clinical and functional outcomes.
Thorax 63, 1040-1045 (2008)
Early detection of airflow obstruction is particularly important among young adults because they are more likely to benefit from intervention. Using the forced expiratory volume in 1 s (FEV(1)) to forced vital capacity (FVC) (FEV(1)/FVC) <70% fixed ratio, airflow obstruction may be underdiagnosed. The lower limit of normal (LLN), which is statistically defined by the lower fifth percentile of a reference population, is physiologically appropriate but it still needs a clinical validation. METHODS: To evaluate the characteristics and longitudinal outcomes of subjects misidentified as normal by the fixed ratio with respect to the LLN, 6249 participants (aged 20-44 years) in the European Community Respiratory Health Survey were examined and divided into three groups (absence of airflow obstruction by the LLN and the fixed ratio; presence of airflow obstruction only by the LLN; presence of airflow obstruction by the two criteria) for 1991-1993. LLN equations were obtained from normal non-smoking participants. A set of clinical and functional outcomes was evaluated in 1999-2002. RESULTS: The misidentified subjects were 318 (5.1%); only 45.6% of the subjects with airflow obstruction by the LLN were also identified by the fixed cut-off. At baseline, FEV(1) (107%, 97%, 85%) progressively decreased and bronchial hyperresponsiveness (slope 7.84, 6.32, 5.57) progressively increased across the three groups. During follow-up, misidentified subjects had a significantly higher risk of developing chronic obstructive pulmonary disease and a significantly higher use of health resources (medicines, emergency department visits/hospital admissions) because of breathing problems than subjects without airflow obstruction (p<0.001). CONCLUSIONS: Our findings show the importance of using statistically derived spirometric criteria to identify airflow obstruction.
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Publication type
Article: Journal article
Document type
Scientific Article
Keywords
airflow obstruction; COPD; asthma; diagnosis
ISSN (print) / ISBN
0040-6376
e-ISSN
1468-3296
Journal
Thorax
Quellenangaben
Volume: 63,
Issue: 12,
Pages: 1040-1045
Publisher
BMJ Publishing Group
Reviewing status
Peer reviewed
Institute(s)
Institute of Lung Health and Immunity (LHI)
Institute of Epidemiology (EPI)
Institute of Epidemiology (EPI)