Long-term intersession variability for single-breath diffusing capacity

Matthew J. Hegewald, Robert L. Jensen, John G. Teeter, Robert A. Wise, Richard J. Riese, Richard D. England, Richard C. Ahrens, Robert O. Crapo, Neil R. MacIntyre

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Background: Characterizing long-term diffusing capacity (DlCO) variability is important in assessing quality control for DlCO equipment and patient management. Long-term DlCO variability has not been reported. Objectives: It was the aim of this study to characterize long-term variability of DlCO in a cohort of biocontrols and to compare different methods of selecting a target value. Methods: Longitudinal DlCO monitoring of biocontrols was performed as part of the inhaled insulin development program; 288 biocontrols were tested twice monthly for up to 5 years using a standardized technique. Variability, expressed either as percent change or DlCO units, was assessed using three different target values. Results: The 90th percentile for mean intersession change in DlCO was between 10.9 and 15.8% (2.6-4.1 units) depending on the target value. Variability was lowest when the mean of all DlCO tests was used as the target value and highest when the baseline DlCO was used. The average of the first six DlCO tests provided an accurate estimate of the mean DlCO value. Using this target, the 90th percentile for mean intersession change was 12.3% and 3.0 units. Variability was stable over time and there were no meaningful associations between variability and demographic factors. Conclusions: DlCO biocontrol deviations >12% or >3.0 units, from the average of the first six tests, indicate that the instrument is not within quality control limits and should be carefully evaluated before further patient testing.

Original languageEnglish (US)
Pages (from-to)377-384
Number of pages8
Issue number5
StatePublished - Oct 2012


  • Biological control
  • Intersession variability
  • Pulmonary diffusing capacity
  • Pulmonary function tests

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine


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