Clinical validation of the lower limit of normal in lung diffusing capacity: is the lower 5th percentile really the best cut-off value?
The lower limit of normal (LLN) in pulmonary diffusing capacity has been determined by using the lower 5th percentile or 95% confidence interval (CI) obtained from a normal reference population. We aimed to test clinical cut-off values (1-99% CI) and to determine the LLN in a population with interstitial lung disease and in healthy subjects, using receiver operating characteristic (ROC) curve analysis. The best cut-off value of the LLN for differentiating subjects with pathologic proven interstitial lung disease (ILD) from healthy subjects was not the 95% CI, but the 90% CI, which gave 95% sensitivity and 100% specificity. Thus, the 90% CI or the lower 10th percentile for the cut-off value of the LLN might be better than the 95% CI or the lower 5th percentile in differentiating subjects with pathologic proven ILD from healthy subjects.
Ra
Seung Won
SW
Department of Pulmonary and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Hong
Sang-Bum
SB
Shim
Tae Sun
TS
Lim
Chae-Man
CM
Lee
Sang-Do
SD
Koh
Younsuck
Y
Kim
Woo Sung
WS
Kim
Dong Soon
DS
Kim
Won Dong
WD
Kim
Tae-Hyung
TH
Oh
Yeon-Mok
YM
D000465:Algorithms; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D017563:Lung Diseases, Interstitial / Q000175:diagnosis / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011653:Pulmonary Diffusing Capacity / Q000502:physiology / Q000592:standards*; D012372:ROC Curve; D012016:Reference Values; D015203:Reproducibility of Results; D012129:Respiratory Function Tests; D012727:Sex Characteristics; D013147:Spirometry