Table 10: The results of a Kappa test (agreement beyond chance) reflecting a statistically significant agreement between the cut-off values of the study biomarkers, used either separately or in combination, and OCT when screening for DR.

	DNR		Retinopathy (Any type of retinopathy)		p (Kappa)	Kappa
	N	%	N	%
Positive VEGF test (at optimum cut-off value of >=124.7 ng/ml)					<0.001	0.383
Negative	24	80.0	33	24.6
Positive	6	20.0	101	75.4
Total	30	100.0	134	100.0
Percent observed agreement=76.2
Positive Sorbitol test (at optimum cut-off value of >= 0.3112 mg/L)					<0.001	0.41
Negative	24	80.0	36	26.9
Positive	6	20.0	98	73.1
Total	30	100.0	134	100.0
Percent observed agreement=68.3%
Parallel tests combination					<0.001	0.523
Negative (both tests negative)	19	63.3	13	9.7
Positive (either test positive)	11	36.7	121	90.3
Total	30	100.0	134	100.0
Percent observed agreement=85.4%
Serial tests combination					<0.001	0.321
Negative (either test negative)	29	96.7	56	41.8
Positive (both tests positive)	1	3.3	78	58.2
Total	30	100.0	134	100.0
Percent observed agreement=65.2%