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Quality control of D_L,CO instruments in global clinical trials

¹ LDS Hospital, , Pulmonary Division, Salt Lake City, UT, and ² Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN, USA.

CORRESPONDENCE: P. Y. Berclaz, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN 46285, USA. Fax: 1 3172776351. E-mail: berclazpi{at}lilly.com

Keywords: Accuracy, inhaled insulin, multicentre trials, quality control, simulator, single-breath diffusing capacity of the lung for carbon monoxide

Received: June 16, 2008
Accepted November 25, 2008

High inter- and intra-laboratory variability exists for the single-breath diffusing capacity of the lung for carbon monoxide (D_L,CO) test. To detect small changes in diffusing capacity in multicentre clinical trials, accurate measurements are essential. The present study assessed whether regular D_L,CO simulator testing maintained or improved instrument accuracy and reduced variability in multicentre trials.

The 125 pulmonary function testing laboratories that participated in clinical trials for AIR® Inhaled Insulin validated and monitored the accuracy of their D_L,CO measuring devices using a D_L,CO simulator, which creates known target values for any device. Devices measuring a simulated D_L,CO different from target by >3 mL·min-1·mmHg^–1 failed testing and were serviced. Device accuracy was assessed over time and with respect to differences in several variables.</emph>

Initially, 31 (25%) laboratories had a D_L,CO device that failed simulator testing. After fixing or replacing devices, 124 (99%) laboratories had passing devices. The percentage of failed tests significantly decreased over time. Differences in geographical region, device type, breath-hold time, temperature and pressure were not associated with meaningful differences in D_L,CO device accuracy.

Regular diffusing capacity of the lung for carbon monoxide simulator testing allows pulmonary function testing laboratories to maintain the accuracy of their diffusing capacity measurements, leading to reduced variability across laboratories in multicentre clinical trials.

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