Figures 1 and 2 show the ROC curves of various
biochemical markers and LDH isoenzymes. From each
ROC curve, the point of minimum difference between the
sensitivity and specificity was decided as the cut-off point.
Tables 2 and 3 show the cut-off points, sensitivity and
specificity for the biochemical markers tested and LDH
isoenzymes, respectively. As shown in Table 2, LDH had
the highest sensitivity (0.66) and specificity (0.67) among
the biochemical parameters tested, while AST and BUN
had sensitivity and specificity above 0.60.
As seen in Table 3, LDH2 and LDH5 showed statistically
significant differences between healthy subjects and
subjects with periodontal disease. LDH2 had sensitivity
of 0.71 and specificity of 0.51. For LDH5, both sensitivity
and specificity were less than 0.5. This means that
evaluation using lower levels of LDH had sensitivity of
0.62 and specificity of 0.56.