Table 1.
Assays on Subjects From CATIE Trials and Comparison Samples
| tTG Antibodies |
IgA-Antigliadin Antibodies |
|||
| CATIE (N = 1401) | Comparison, (N = 900) | CATIE, (N = 1401) | Comparison, (N = 900) | |
| Total positivea (medium plus high) | 76 (5.4%) | 7 (0.80%) | 323 (23.1%) | 28 (3.1%) |
| Low | 1325 (94.6%) | 893 (99.2%) | 1078 (76.9%) | 872 (96.9%) |
| Medium | 55 (3.9%)b | 7 (0.80%)b | 155 (11.1%)c | 16 (1.8%)c |
| High | 21 (1.5%)b | 0d | 168 (12.0%)c | 12 (1.3%)c |
| 100.0% | 100.0% | 100.0% | 100.0% | |
Note: Standard statistical rounding was used across test results. CATIE, Clinical Antipsychotic Trials of Intervention Effectiveness; tTG, antibody to transglutaminase; IgA, immunoglobulin A.
The cutoff scores are expressed as arbitrary units established by the manufacturers. INOVA Diagnostics, Inc—cutoff scores for tTG-antibody to gliadin (AGA) and AGA-IgA are each set at the same level: low or negative, <20 units; weak positive, 20–30 units; strong positive >30 units. Scimedx—cutoff scores are negative, <7; positive, >7. INOVA Diagnostics, Inc, kits were employed for CATIE sample tTG tests and all AGA tests. Scimedx kits were employed for comparison tTG tests.
χ2 = 392.0, df = 2, P < .001.
χ2 = 1884.6, df = 2, P < .001.
The manufacturer does not distinguish medium from high; therefore, subjects above the threshold for “low” were placed in the medium category to be conservative.