Prediction of ILD by Multivariate regression analysis and ROC
curve analysis:
The most sensitive variable to detect ILD in CTD child was KL-6 and
FVC%. According to the Receiver Operating Characteristic Curve (ROC)
analysis, the area under the curve was of 0.977 and the cut-off value of
serum KL-6 to distinguish ILD was 63.4 U/ml, with sensitivity of 95.2
%, specificity of 89.7%, positive predictive value of 83.26% and
negative predictive value of 97.2% (figure 2). Moreover, FVC% Receiver
Operating Characteristic Curve (ROC) analysis shows that the area under
the curve was of 0.979 and the cut-off value of serum FVC% to
distinguish ILD was 79, with sensitivity of 95.2%, specificity of
100%, positive predictive value of 100% and negative predictive value
of 95.4% (figure 3). Comparison between KL6 and FVC% Roc curves shows
that there is no statistical difference (P = 0.7385) between KL6 and
FVC% ROC curves.