Table 2—

The optimal critical line for different cost-to-benefit ratio R

RFPG at the intercept of OCL and HbA1c = 0 (mg/dl)HbA1c at the intercept of OCL and FPG = 110 (%)HbA1c at the intercept of OCL and FPG = 126 (%)Z*k*Specificity (%)Sensitivity (%)
SHS baseline examination (OCL: 0.89 × HbA1c + 0.11 × FPG = Z*)
P /(1 − P)162.936.544.5617.9240.22276.8158.82
 0.05153.265.353.3716.8610.09018.0397.06
 0.10154.225.473.4916.9660.09923.8995.10
 0.15157.745.903.9217.3530.13944.9683.33
 0.20160.506.244.2617.6570.18061.8371.57
 0.25162.936.544.5617.9240.22276.8158.82
 0.30164.316.714.7418.0760.25081.9752.94
 0.35164.316.714.7418.0760.25081.9752.94
 0.40164.316.714.7418.0760.25081.9752.94
 0.45164.316.714.7418.0760.25081.9752.94
 0.50169.167.315.3418.6100.36295.3226.47
 1.00170.787.515.5418.7880.40497.4219.61
SHS second examination (OCL: 0.106 × HbA1c + 0.078 × FPG = Z*)
P /(1 − P)120.317.61−4.209.4330.18936.3383.72
 0.05117.315.40−6.419.1970.1559.3498.84
 0.10117.315.40−6.419.1970.1559.3498.84
 0.15117.315.40−6.419.1970.1559.3498.84
 0.20120.317.61−4.209.4330.18936.3383.72
 0.25120.317.61−4.209.4330.18936.3383.72
 0.30120.317.61−4.209.4330.18936.3383.72
 0.35127.3112.780.979.9810.28783.7430.23
 0.40127.3112.780.979.9810.28783.7430.23
 0.45127.3112.780.979.9810.28783.7430.23
 0.50128.2613.481.6710.0560.30387.5424.42
 1.00132.8016.845.0210.4120.38298.963.49
  • R = the costs-to-benefit ratio; P = the prevalence of diabetes in IFG participants, which is estimated as 0.193 and 0.229 based on the data from the baseline and second exam, respectively; k* = the optimal cutoff point; Z* = log[k* /(1 − k*)]− a, where a is the estimated intercept in the fitted logistic regression model on FPG and HbA1c, and a = −19.176 and −10.891 based on the data from the baseline and second exam, respectively. All variables are defined in research design and methods (statistical analysis). OCL, optimal critical line.