Table 1.

Distribution of DR staging between two retina specialists for internal and external validation datasets

Internal validation set							Weighted Kappa	0.953
Observer B	Observer A					Total	Standard error	0.005
	No DR	Mild NPDR	Mod NPDR	Severe NPDR	PDR		95% CI	0.944-0.962
No DR	121	4	0	0	0	125 (8.2%)
Mild NPDR	8	16	6	0	0	30 (2.0%)
Mod NPDR	1	3	468	21	0	493 (32.2%)
Severe NPDR	0	0	11	130	37	178 (11.6%)
PDR	0	0	0	3	704	707 (46.1%)
Total	130	23	485	154	741	1533
External Validation Set							Weighted Kappa	0.961
Observer B	Observer A					Total	Standard error	0.006
	No DR	Mild NPDR	Mod NPDR	Severe NPDR	PDR		95% CI	0.949-0.972
No DR	538	10	0	0	0	548 (45.7%)
Mild NPDR	6	214	8	2	0	230 (19.2%)
Mod NPDR	1	0	329	5	2	337 (28.1%)
Severe NPDR	0	0	10	50	4	64 (5.3%)
PDR	0	0	0	0	21	21 (1.8%)
Total	545	224	347	57	27	1200

The percentage values in brackets indicate the proportion of cases under each stage of DR