Level 1 graders (n=410 patient images) | Level 2 graders (n=410 patient images) | Level 3 graders (n=260 patient images) | |
Any DR | |||
Sensitivity (%) (95% CI) | 41.8 (33.9 to 50.1) | 42.5 (34.5 to 50.7) | 42.2 (33.1 to 51.8) |
Specificity (%) (95% CI) | 87.9 (83.3 to 91.7) | 98.8 (96.6 to 99.8) | 100 (97.5 to 100) |
PPV (%) (95% CI) | 67.4 (57.0 to 76.6) | 95.6 (87.6 to 99.1) | 100 (92.7 to 100) |
NPV (%) (95% CI) | 71.7 (66.4 to 76.7) | 74.3 (69.3 to 78.8) | 68.2 (61.5 to 74.5) |
Referable DR | |||
Sensitivity (%) (95% CI) | 19.2 (9.63 to 32.5) | 13.5 (5.59 to 25.8) | 10.5 (2.94 to 24.8) |
Specificity (%) (95% CI) | 97.2 (94.9 to 98.7) | 100 (99.0 to 100) | 99.5 (97.5 to 100) |
PPV (%) (95% CI) | 50.0 (27.2 to 72.8) | 100 (59.0 to 100) | 80.0 (28.4 to 99.5) |
NPV (%) (95% CI) | 89.2 (85.7 to 92.1) | 88.8 (85.3 to 91.7) | 86.7 (81.9 to 90.6) |
Referable DMO | |||
Sensitivity (%) (95% CI) | 5.8 (1.91 to 13.0) | 20.9 (12.9 to 31.0) | 16.9 (8.76 to 28.3) |
Specificity (%) (95% CI) | 97.2 (94.8 to 98.7) | 99.4 (97.8 to 99.9) | 100 (98.1 to 100) |
PPV (%) (95% CI) | 35.7 (12.8 to 64.9) | 90.0 (68.3 to 98.8) | 100 (71.5 to 100) |
NPV (%) (95% CI) | 79.5 (75.2 to 83.4) | 82.6 (78.4 to 86.2) | 78.3 (72.7 to 83.3) |
Grading criteria: UK National Diabetic Eye Screening Programme (NDESP) classification system (see online supplemental table S1 for more details).
Any DR, is defined as grades R1, R2, R3s, R3a and U. Referable DR is defined as grades R2, R3a and U. Referable DMO is defined as grades M1 and U.
Sensitivity is the ability of a test to correctly identify patients with a disease and specificity is the ability of a test to correctly identify people without the disease Positive predictive value (PPV) is the proportion of those who test positive who have the condition (true positives) and negative predictive value (NPV) is the proportion of those who test negative who do not have the condition (true negatives).
DMO, diabetic macular oedema; DR, diabetic retinopathy.