Table 1.
Characteristics of patient cohort stratified by the presence or absence of a positive ANCA test result
| Characteristic | Total Cohort (n=79) | ANCA-Positivea (n=26 [33.3%]) | ANCA-Negative (n=52 [66.7%]) | P Valueb |
|---|---|---|---|---|
| Age, yr | 63.4 (48.5–74.5) | 69.7 (58.1–80.6) | 58.3 (44.6–69.7) | <0.01 |
| Women | 35 (44.3) | 13 (50) | 21 (40.4) | 0.42 |
| Systems involved | 0.85 | |||
| Kidney alone | 61 (77.2) | 21 (80.8) | 39 (75) | |
| Lung alone | 1 (1.3) | 0 | 1 (1.9) | |
| Both kidney and lung | 17 (21.5) | 5 (19.2) | 12 (23.1) | |
| Linear IgG on renal biopsy | 58 (73.4) | 19 (73.1) | 38 (73.1) | 1.0 |
| ANCA subtypec | NA | |||
| Anti-PR3 | 10 (12.8) | 10 (40) | NA | |
| Anti-MPO | 12 (15.4) | 12 (48) | NA | |
| Anti-PR3 and anti-MPO | 3 (3.8) | 3 (12) | NA | |
| Anti-GBM antibody level, U/ml | 212 (96–530) | 170 (96–400) | 273 (88–585) | 0.32 |
| Negative anti-GBM antibody result | 5 (6.3) | 2 (7.7) | 3 (5.8) | 1.0 |
| Dialysis at presentation | 58 (73.4) | 18 (69.2) | 40 (76.9) | 0.46 |
| Patient survival (95% CI), % | 0.47 | |||
| 1-yr survival | 73.7 (62.2 to 82.2) | 71.8 (49.6 to 85.5) | 74.2 (59.6 to 84.1) | |
| 5-yr survival | 59.1 (45.1 to 70.6) | 53.3 (28.2 to 73.1) | 61.0 (43.7 to 74.5) |
Numbers are expressed as number (percentage) or median (interquartile range) unless otherwise stipulated. PR3, proteinase 3; NA, not applicable; MPO, myeloperoxidase; 95% CI, 95% confidence interval.
a
ANCA test was performed in 78 of 79 cases.
b
For difference between ANCA-positive and ANCA-negative groups.
c
ELISA was performed in 25 of 26 patients who were ANCA positive by indirect immunofluorescence.