Table 1 Clinical characteristics of 93 patients with MPA
|  | Low BMI (<  18.5) (n = 22) | Normal BMI (18.5–23.0) (n = 53) | High BMI (>  23) (n = 18) | P value |
|---|---|---|---|---|
Baseline characteristics | ||||
Age (years) | 78 (70–81) | 73 (69–78) | 75 (69–78) | 0.455 |
Male sex | 15 (68.2) | 27 (50.9) | 8 (44.4) | 0.267 |
BMI (kg/m2) | 17.9 (17.0–18.3) | 21.0 (20.0–22.1) | 24.5 (23.7–26.4) | < 0.001 |
Body weight loss > 10% within 6 months before diagnosis | 12 (54.5) | 24 (45.3) | 4 (22.2) | 0.016 |
lymphocyte count (/μL) | 964 (792–1101) | 1008 (779–1336) | 1120 (935–1367) | 0.221 |
Serum creatinine level (mg/dL) | 1.6 (1.0–6.5) | 1.8 (0.9–3.8) | 1.3 (0.6–2.3) | 0.212 |
Serum albumin level (mg/dL) | 3.0 (2.6–3.2) | 2.8 (2.4–3.3) | 3.0 (2.4–3.6) | 0.739 |
Serum IgG level (mg/dL) | 1826 (1590–1967) | 1818 (1602–2019) | 1760 (1346–2023) | 0.583 |
CRP level (mg/dL) | 6.5 (2.3–11.1) | 3.6 (1.2–9.2) | 5.8 (0.3–13.2) | 0.379 |
Diabetes mellitus | 7 (31.8) | 9 (17.0) | 4 (22.2) | 0.362 |
Antibody | Â | Â | Â | 0.122 |
 MPO-ANCA | 22 (100) | 53 (100) | 17 (94.4) |  |
 PR3-ANCA | 0 (0) | 0 (0) | 1 (5.6) |  |
 BVAS | 15 (12–17) | 14 (11–16) | 14 (12–14) | 0.591 |
 FFS | 2 (2–3) | 2 (2–3) | 2 (2–3) | 0.618 |
Organ involvement | ||||
 General | 22 (100) | 53 (100) | 17 (94.4) | 0.122 |
 Cutaneous | 3 (13.0) | 1 (1.8) | 2 (10.5) | 0.111 |
 Ear nose and throat | 4 (18.2) | 14 (26.4) | 5 (27.8) | 0.713 |
 Chest | 6 (27.3) | 20 (37.7) | 5 (27.8) | 0.584 |
  Nodules or cavities | 0 (0) | 0 (0) | 0 (0) |  |
  Pleural effusion / pleurisy | 0 (0) | 2 (3.8) | 0 (0) |  |
  Endobronchial involvement | 0 (0) | 0 (0) | 0 (0) |  |
  Infiltrate | 6 (100) | 15 (75.0) | 4 (80.0) |  |
  Alveolar hemorrhage | 0 (0) | 3 (5.7) | 1 (5.6) |  |
Cardiovascular | 0 (0) | 0 (0) | 0 (0) | 0.000 |
Abdominal | 1 (4.6) | 1 (1.9) | 0 (0) | 0.603 |
Renal | 19 (86.4) | 42 (79.3) | 14 (77.8) | 0.733 |
 HD requirement at MPA diagnosis | 5 (22.7) | 1 (1.9) | 2 (11.1) | 0.013 |
Nervous system | 4 (18.2) | 8 (15.1) | 4 (22.2) | 0.779 |
Induction immunosuppressive therapy | ||||
 mPSL pulse therapy | 11 (50.0) | 25 (47.2) | 8 (44.4) | 0.940 |
 Intravenous cyclophosphamide | 3 (13.6) | 4 (7.6) | 1 (5.6) | 0.608 |
 Rituximab | 0 (0) | 3 (5.7) | 2 (11.1) | 0.298 |
Maintenance immunosuppressive therapy | Â | Â | Â | 0.381 |
 Glucocorticoidmonotherapy | 16 (72.7) | 38 (71.7) | 13 (72.2) |  |
 Oralcyclophosphamide | 0 (0) | 1 (1.9) | 1 (5.6) |  |
 zathioprine | 5 (22.7) | 12 (22.6) | 2 (11.1) |  |
 Methotrexate | 0 (0) | 0 (0) | 0 (0) |  |
 Mizoribine | 1 (4.6) | 0 (0) | 0 (0) |  |
 Rituximab | 0 (0) | 2 (3.8) | 2 (11.1) |  |
Outcomes | ||||
 Remission | 18 (81.8) | 48 (90.6) | 16 (88.9) | 0.562 |
 Relapse | 7 (38.9) | 17 (35.4) | 6 (37.5) | 0.963 |
 Severe infection | 14 (63.6) | 13 (24.5) | 2 (11.1) | < 0.001 |
 HD | 8 (36.4) | 11 (20.8) | 4 (22.2) | 0.348 |
 Death | 7 (31.8) | 13 (24.5) | 2 (11.1) | 0.030 |
 Infection | 7 (100) | 6 (46.2) | 1 (50.0) |  |
 Vasculitis | 0 (0) | 3 (23.1) | 0 (0) |  |
 Malignancy | 0 (0) | 2 (15.4) | 0 (0) |  |
 Cardiovascular | 0 (0) | 0 (0) | 1 (50.0) |  |
 Unknown | 0 (0) | 2 (15.4) | 0 (0) |  |
Observation period (months) | 18 (4–76) | 17 (6–47) | 32 (13–53) | 0.828 |