Table 7: Validity parameters for VEGF-A and sorbitol when used as tests to diagnose and determine the type of DR.

Study groups and variables Optimum cut-off value Sensitivity Specificity Accuracy PPV at pretest probability NPV at pretest probability = 10%
50% 90%
DNR X DR
VEGF (ng/ml) 124.7 73.1 80 74.4 78.5 97.1 96.4
Sorbitol (mg/ml) 0.3112 75.4 80 76.2 79 97.1 96.7
DNR X NPDR
VEGF (ng/ml) 285.8 66.7 60.5 62.7 62.8 93.8 94.2
Sorbitol
(mg/ml)
0.4065 68.8 75.6 73.1 73.8 96.2 95.6
NPDR X PDR
VEGF (ng/ml) 173.9 79.2 93.3 84.6 92.2 99.1 97.6
Sorbitol (mg/ml) 0.3363 79.2 100 87.2 100 100 97.7