Table 2.
Positivity for t-GADA, f-GADA, and combined positivity for t-GADA and f-GADA among progressors and nonprogressors in the study population (n = 760), and the sensitivities, specificities, and positive and negative predictive values of positivity for t-GADA, f-GADA, and combined positivity for t-GADA and f-GADA for type 1 diabetes
| Autoantibody positivity | Progressors | Nonprogressors | P-value | Sensitivity | Specificity | PPV | NPV |
|---|---|---|---|---|---|---|---|
| n (%) | % (95% CI) | ||||||
| t-GADA | 137 (79) | 314 (54) | <0.001 | 79 (73-84) | 46 (45-48) | 30 (28-32) | 88 (85-91) |
| f-GADA | 132 (76) | 499 (85) | 0.004 | 76 (70-81) | 15 (13-16) | 21 (19-22) | 67 (60-75) |
| f-GADA and t-GADA | 129 (74) | 310 (53) | <0.001 | 74 (68-80) | 47 (45-49) | 29 (27-32) | 86 (83-89) |
Abbreviations: f-GADA, autoantibodies to full-length GAD(1-585); NPV, negative predictive value; PPV, positive predictive value; t-GADA, autoantibodies to N-terminally truncated GAD(96-585).