title: Clinical validation of the lower limit of normal in lung diffusing capacity: is the lower 5th percentile really the best cut-off value?
abstract: 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.
authors.affiliation: Department of Pulmonary and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
authors.forename: Seung Won
authors.initials: SW
authors.lastname: Ra
authors.forename: Sang-Bum
authors.initials: SB
authors.lastname: Hong
authors.forename: Tae Sun
authors.initials: TS
authors.lastname: Shim
authors.forename: Chae-Man
authors.initials: CM
authors.lastname: Lim
authors.forename: Sang-Do
authors.initials: SD
authors.lastname: Lee
authors.forename: Younsuck
authors.initials: Y
authors.lastname: Koh
authors.forename: Woo Sung
authors.initials: WS
authors.lastname: Kim
authors.forename: Dong Soon
authors.initials: DS
authors.lastname: Kim
authors.forename: Won Dong
authors.initials: WD
authors.lastname: Kim
authors.forename: Tae-Hyung
authors.initials: TH
authors.lastname: Kim
authors.forename: Yeon-Mok
authors.initials: YM
authors.lastname: Oh
mesh_terms: 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