Underestimation of airflow obstruction among young adults using FEV1/FVC<70% as a fixed cut-off: a longitudinal evaluation of clinical and functional outcomes
2008 (English)In: Thorax, ISSN 0040-6376, Vol. 63, no 12, 1040-1045 p.Article in journal (Refereed) Published
Background: 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 (FEV1) to forced vital capacity (FVC) (FEV1/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, FEV1 (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.
Place, publisher, year, edition, pages
2008. Vol. 63, no 12, 1040-1045 p.
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-16794DOI: 10.1136/thx.2008.095554ISI: 000261033800005PubMedID: 18492741OAI: oai:DiVA.org:uu-16794DiVA: diva2:44565