Table 2.
Diagnostic test accuracy of DR graders in Vietnam against a reference standard from the UK after additional DR training was delivered
| Level 1 graders (n=115 patient images) | Level 2 graders (n=115 patient images | Level 3 graders (n=61 patient images) | |
| Any DR | |||
| Sensitivity (%) (95% CI) | 87.2 (74.3 to 95.2) | 68.1 (52.9 to 80.9) | 51.3 (34.8 to 67.6) |
| Specificity (%) (95% CI) | 95.6 (87.6 to 99.1) | 95.6 (87.6 to 99.1) | 100 (84.6 to 100) |
| PPV (%) (95% CI) | 93.2 (81.3 to 98.6) | 91.4 (76.9 to 98.2) | 100 (83.2 to 100) |
| NPV (%) (95% CI) | 91.5 (82.5 to 96.8) | 81.3 (71.0 to 89.1) | 53.7 (37.4 to 69.3) |
| P-value comparing sensitivity to Phase I | p=0.000 | p=0.002 | p=0.326 |
| Referable DR | |||
| Sensitivity (%) (95% CI) | 53.3 (26.6 to 78.7) | 40.0 (16.3 to 67.7) | 58.3 (27.7 to 84.8) |
| Specificity (%) (95% CI) | 90.0 (82.4 to 95.1) | 93.0 (86.1 to 97.1) | 100 (92.7 to 100) |
| PPV (%) (95% CI) | 44.4 (21.5 to 69.2) | 46.2 (19.2 to 74.9) | 100 (59.0 to 100) |
| NPV (%) (95% CI) | 92.8 (85.7 to 97.0) | 91.2 (83 to 95.9) | 90.7 (79.7 to 96.9) |
| P-value comparing sensitivity to Phase I | p=0.009 | p=0.022 | p=0.001 |
| Referable DMO | |||
| Sensitivity (%) (95% CI) | 56.3 (29.9 to 80.2) | 43.8 (19.8 to 70.1) | 61.5 (31.6 to 86.1) |
| Specificity (%) (95% CI) | 97.0 (91.4 to 99.4) | 93.9 (87.3 to 97.7) | 100 (92.6 to 100) |
| PPV (%) (95% CI) | 75.0 (42.8 to 94.5) | 53.8 (25.1 to 80.8) | 100 (63.1 to 100) |
| NPV (%) (95% CI) | 93.2 (86.5 to 97.2) | 91.2 (83.9 to 95.9) | 90.6 (79.3 to 96.9) |
| P-value comparing sensitivity to Phase I | p=0.000 | p=0.051 | p=0.002 |
Grading criteria: UK National Diabetic Eye Screening Programme (NDESP) classification system (See online supplemental table S1 for more details).
Criteria: 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. χ2 used to compare sensitivity between phase I and II.
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.