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Logo of bmcpmBioMed Centralsearchsubmit a manuscriptregisterthis articleBMC Pulmonary Medicine
 
BMC Pulm Med. 2012; 12: 12.
Published online 2012 March 22. doi:  10.1186/1471-2466-12-12
PMCID: PMC3355014

Lung function decline in relation to diagnostic criteria for airflow obstruction in respiratory symptomatic subjects

Abstract

Background

Current COPD guidelines advocate a fixed < 0.70 FEV1/FVC cutpoint to define airflow obstruction. We compared rate of lung function decline in respiratory symptomatic 40+ subjects who were 'obstructive' or 'non-obstructive' according to the fixed and/or age and gender specific lower limit of normal (LLN) FEV1/FVC cutpoints.

Methods

We studied 3,324 respiratory symptomatic subjects referred to primary care diagnostic centres for spirometry. The cohort was subdivided into four categories based on presence or absence of obstruction according to the fixed and LLN FEV1/FVC cutpoints. Postbronchodilator FEV1 decline served as primary outcome to compare subjects between the respective categories.

Results

918 subjects were obstructive according to the fixed FEV1/FVC cutpoint; 389 (42%) of them were non-obstructive according to the LLN cutpoint. In smokers, postbronchodilator FEV1 decline was 21 (SE 3) ml/year in those non-obstructive according to both cutpoints, 21 (7) ml/year in those obstructive according to the fixed but not according to the LLN cutpoint, and 50 (5) ml/year in those obstructive according to both cutpoints (p = 0.004).

Conclusion

This study showed that respiratory symptomatic 40+ smokers and non-smokers who show FEV1/FVC values below the fixed 0.70 cutpoint but above their age/gender specific LLN value did not show accelerated FEV1 decline, in contrast with those showing FEV1/FVC values below their LLN cutpoint.

Keywords: Airflow obstruction, Chronic obstructive pulmonary disease, Diagnosis, Lung function decline, Primary care, Spirometry

Articles from BMC Pulmonary Medicine are provided here courtesy of BioMed Central