American Thoracic Society/European Respiratory Society 2005 standardization of DL measurement: impact on performance.
OBJECTIVE
An updated standardization statement on measurement of DL(CO) 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 DL(CO) testing.


METHODS
We prospectively evaluated 55 Chinese patients without previous experience of the DL(CO) 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 DL(CO) 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 DL(CO) 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 DL(CO) measurement were improved when the new recommendations were adopted. The effects on measurement variability and reported results were minimal.
Tuberculosis and Chest Unit, Grantham Hospital, Hong Kong, China. skfleung@netvigator.com
Simon Kwok Fai
SK
Leung
Wing Wai
WW
Yew
Poon Chuen
PC
Wong
Yee Kit
YK
Tse
Wing Sze
WS
Law
Chi Chiu
CC
Leung
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002248:Carbon Monoxide / Q000378:metabolism*; D002648:Child; D002681:China; D005060:Europe; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011653:Pulmonary Diffusing Capacity / Q000592:standards*; D012129:Respiratory Function Tests / Q000592:standards*; D012955:Societies, Medical; D014481:United States
D002248:Carbon Monoxide