Table 2.
Comparison of the percentage of study patients with at least one serum sample with PR3-ANCA above the thresholds >0, >1, >2, and ≥6 U/ml compared with matched healthy controls
| PR3 Antibody, U/ml (yr) | Patients (%) | Controls (%) | Odds Ratio | 95% Confidence Interval | P Value (Fisher’s Exact Test) |
|---|---|---|---|---|---|
| >/6 | |||||
| All | 63 (17/27) | 0 (0/27) | 48.6a | 5.7 to 413a | <0.001 |
| <1 | 74 (14/19) | 0 (0/19) | 57a | 6.0 to 73a | <0.001 |
| 1–5 | 31 (4/13) | 0 (0/13) | 7.2a | 0.72 to 72.7a | 0.1 |
| >5 | 0 (0/15) | 0 (0/15) | 1.0a | 0.1 to 17.5a | 1.0 |
| > 2 | |||||
| All | 78 (21/27) | 0 (0/27) | 99a | 11.1 to 885a | <0.001 |
| <1 | 79 (15/19) | 0 (0/19) | 76a | 7.7 to 751a | <0.001 |
| 1–5 | 39 (5/13) | 0 (0/13) | 9.8a | 1.0 to 97a | 0.03 |
| >5 | 13 (2/15) | 0 (0/13) | 3.5a | 0.3 to 37.5a | 0.48 |
| >1 | |||||
| All | 85 (23/27) | 4 (1/27) | 150 | 15.6 to 1436 | <0.001 |
| <1 | 79 (15/19) | 0 (0/19) | 76a | 7.7 to 751a | <0.001 |
| 1–5 | 69 (9/13) | 0 (0/13) | 32.5a | 3.1 to 338a | <0.001 |
| >5 | 13 (2/15) | 7 (1/15) | 2.2 | 0.2 to 26.7 | 0.5 |
| > 0 | |||||
| All | 96 (26/27) | 56 (15/27) | 20.8 | 2.5 to 176 | <0.001 |
| <1 | 95 (18/19) | 37 (7/19) | 30.9 | 3.4 to 284 | <0.001 |
| 1–5 | 80 (10/13) | 46 (6/13) | 3.9 | 0.72 to 21.1 | 0.23 |
| >5 | 73 (11/15) | 40 (6/15) | 4.1 | 0.9 to 19.3 | 0.14 |
Not all patients had samples available for each time period. If multiple serum samples were present for a patient in a specific subgroup analysis time period, the highest antibody level dictated group assignment. For example, the one control with PR3-ANCA >1 U/ml occurred in the >5-year time period. A higher percentage of patients had an elevated PR3-ANCA <1 year before diagnosis than over all time periods because the majority of patients without a banked sample a year before diagnosis did not have an elevated level. PR3, proteinase-3.
Estimated due to actual infinite value.