Baseline clinical, biological, and histologic features of the 60 patients with systemic vasculitis and chronic active HCV infection according to presence or absence of detectable MC.
| Features | Cases MC–, n = 12 | Controls MC+, n = 48 | Unadjusted OR (95% CI) | p |
|---|---|---|---|---|
| Clinical features | ||||
| Arthralgia | 4/12 (33) | 34/48 (71) | 0.2 (0.5–0.8) | 0.02 |
| Purpura | 6/12 (50) | 40/48 (83) | 0.2 (0.07–0.9) | 0.03 |
| Peripheral neuropathy | 9/12 (75) | 36/48 (75) | 1 (0.2–4.1) | 1 |
| Polyneuropathy | 7 | 25 | ||
| Multiple mononeuropathy | 2 | 11 | ||
| Renal involvement | 2/12 (17) | 15/48 (31) | 0.4 (0.1–2.2) | 0.3 |
| Central nervous system involvement | 2/12 (17) | 6/48 (13) | 1.4 (0.3–7.2) | 0.7 |
| Gastrointestinal tract involvement | 1/12 (8) | 3/48 (6) | 1.3 (0.1–12.8) | 0.8 |
| B cell lymphoma | 1/12 (8) | 7/48 (15) | 1.2 (0.2–6.7) | 0.9 |
| Biological features | ||||
| ALT, median (range), IU/l | 32 (19–170) | 45 (18–520) | 1 (0.98–1.02) | 0.8 |
| C-reactive protein, median (range), mg/l | 2.5 (0–158) | 2 (1–89) | 1.01 (0.99–1.03) | 0.5 |
| C3, mean (SD), mg/l | 1.17 ± 0.21 | 0.93 ± 0.23 | 1.4 (1.1–2)* | 0.01 |
| C4, median, (range), mg/l | 0.25 (0.06–0.41) | 0.04 (0.01–0.3) | 11.3 (1.6–79)* | < 0.001 |
| Low C4 level | 1/10 (10) | 35/42 (83) | 0.05 (0.01–0.4) | < 0.001 |
| IgM, median (range), g/l | 0.6 (0.3–1.8) | 1.9 (0.6–9.6) | 0.1 (0–0.8) | < 0.001 |
| IgG, mean (SD), g/l | 13.7 ± 4.7 | 12.7 ± 7.8 | 1 (0.9–1.1) | 0.9 |
| RF positivity | 1/12 (8) | 36/44 (82) | < 0.001 | |
| Characteristics of MC | ||||
| Type II | — | 39 (81) | — | |
| Monoclonal κ | — | 37 | — | |
| Monoclonal λ | — | 2 | — | |
| Type III | — | 9 (19) | — | |
| Histologic features | 0.2 | |||
| MC-type vasculitis | 10/12 (83) | 16/24 (67) | 1 | |
| Necrotizing vasculitis | 2/12 (17) | 8/24 (33) | 0.3 (0.03–2.3) | |
↵* OR presented for a 0.1 increase of C3 and C4. PAN: polyarteritis nodosa; HCV: hepatitis C virus; ALT: alanine aminotransferase; RF: rheumatoid factor.