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Intersession Variability in Single-Breath Diffusing Capacity in Diabetics Without Overt Lung Disease.| Authors: | Michael B Drummond, Pamela F Schwartz, William T Duggan, John G Teeter, Richard J Riese, Richard C Ahrens, Robert O Crapo, Richard D England, Neil R Macintyre, Robert L Jensen, Robert A Wise | | Language: | ENG. | | Date: | 9-5-2008 | | Journal: | American journal of respiratory and critical care medicine
(1535-4970)
| | Release: | Am J Respir Crit Care Med. 8 May 2008 | |
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Abstract:
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RATIONALE: American Thoracic Society guidelines state that a >/=10% intersession change in diffusing capacity of the lung (DLCO) should be considered clinically significant. However, little is known about the short-term intersession variability in DLCO in untrained subjects or how variability is affected by rigorous external quality control. Obejctives: To characterize the intersession variability of DLCO and the effect of different quality control methods in untrained individuals without significant lung disease.
METHODS:
Data were pooled from the comparator arms of 14 pre-registration trials of inhaled insulin that included non-smoking diabetic patients without significant lung disease. 699 participants performed repeated DLCO measurements using a highly standardized technique. 948 participants performed repeated measurements using routine clinical testing. MEASUREMENTS AND
MAIN
RESULTS:
The mean intersession absolute change in DLCO using the highly standardized method was 1.45 mL/min/mm Hg (5.64%) compared to 2.49 mL/min/mm Hg (9.52% ) in the routine testing group (p<0.0001 for both absolute and percent difference). The variability in absolute intersession change in DLCOincreased with increasing baseline DLCOvalues, whereas the absolute percent intersession change was stable across baseline values. Depending upon the method, 15.5-35.5% of participants had an intersession change of >/=10%. A >/=20% threshold would reduce this percentage of patients to 1-10%.
CONCLUSIONS:
Intersession variability in DLCO measurement is dependent upon the method of testing used and baseline DLCO. Using a more liberal threshold to define meaningful intersession change may reduce the misclassification of normal variation as abnormal change.
| | Copyright: | American journal of respiratory and critical care medicine
Division of Pulmonary and Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA. | | Full text: | | | |
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