American Thoracic Society/European Respiratory Society 2005 standardization of DLCO measurement:: Impact on performance

Background and objective: An updated standardization statement on measurement of DLCO was issued by the American Thoracic Society (ATS)/European Respiratory Society (ERS) Task Force in 2005. The aim of this study was to evaluate the effects of new recommendations on the success rate, test efficiency, measurement variability and reported results of DLCO testing. Methods: We prospectively evaluated 55 Chinese patients without previous experience of the DLCO test in 2006. Performance and results of the test according to the ATS 1995 and ATS/ERS 2005 acceptability criteria were compared. Results: Using the 2005 criteria, the success rate (maximum four trials) improved from 65% to 85% (change: 20%, 95% CI: 9-31%; P = 0.001). The test efficiency as measured by two-trial and three-trial success rates increased from 25% and 51% to 60% and 78%, respectively (both P < 0.0005). The measurement variability was defined as the mean of absolute differences between two acceptable trial results of DLCO for each patient. The means (SD) were 0.60 (0.53) and 0.53 (0.57) mL/min/mm Hg for the old and new criteria, respectively (P = 0.623). The mean DLCO decreased slightly by 0.5%, from 14.93 +/- 5.74 (SD) (old criteria) to 14.86 +/- 5.75 mL/min/mm Hg (new criteria) overall, with a mean difference (SD) of -0.07 (0.20) mL/min/mm Hg for the 36 subjects meeting both criteria (paired t-test, P = 0.048). Conclusions: Success rate and test efficiency for DLCO measurement were improved when the new recommendations were adopted. The effects on measurement variability and reported results were minimal.