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Measurement variability in single-breath diffusing capacity of the lung.
Naresh M Punjabi1, David Shade, Anshul M Patel
1Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, MD, USA. npunjabi@jhmi.edu
Chest
|April 10, 2003
Summary
Pulmonary function testing for diffusing capacity of the lung (DLCO) generally exceeds current reproducibility standards. Future guidelines should favor absolute difference criteria over percentage-based measures for DLCO measurements.
Area of Science:
- Pulmonary Medicine
- Respiratory Physiology
- Clinical Diagnostics
Background:
- The single-breath diffusing capacity of the lung (DLCO) is a standard pulmonary function test.
- Current American Thoracic Society (ATS) and European Respiratory Society (ERS) guidelines set specific reproducibility criteria for DLCO measurements.
Purpose of the Study:
- To evaluate if a typical pulmonary function laboratory meets existing DLCO reproducibility criteria.
- To explore the suitability of alternative reproducibility criteria for DLCO measurements.
Main Methods:
- A cross-sectional study was conducted in a university-based pulmonary function laboratory.
- Data from 6,193 patients undergoing spirometry, lung volumes, and DLCO measurements were analyzed.
Main Results:
- Over 98% of patients met the ATS criteria for DLCO reproducibility.
- Measurement variability, assessed by coefficient of variation and percentage difference, increased with lower baseline DLCO and FEV1.
- An absolute difference criterion (2-2.5 mL/min/mm Hg) showed high compliance (91.5%-95.8%).
Conclusions:
- DLCO measurement reproducibility in clinical practice often surpasses current standards.
- An absolute difference criterion may be more appropriate for future DLCO reproducibility standards than percentage-based criteria.