Table 2.

Comparison of clinical and laboratory features and outcomes of patients with and without reduced serum C3

VariableLow sC3Normal sC3P Value
Patients (n)1426
Men/women (n/n)10/416/100.73
Age at disease onset (yr)72.4±962.1±160.04
Type of AAV (GPA/MPA) (n/n)3/1110/160.32
ANCA specificity (PR3/MPO) (n/n)3/1110/160.32
Organ involvement
 Renal limited vasculitis480.72
 Pulmonary involvement10130.21
 Peripheral nervous system490.72
Mean arterial pressure (mmHg)100.5±9.2100.8±7.80.79
eGFR (ml/min per 1.73 m2)9.3 (2.4–23.5)12.7 (3.7–45.0)0.06
sC3 (mg/dl)72.7 (47–89)124.5 (97.5–211)<0.001
Low serum C4, n (%)1 (7.1)0 (0)0.35
Proteinuria (g/24 h)2.3 (0.3–7)3 (0.3–7.6)0.75
Immunosuppressive therapy, n (%)
 Cyclophosphamide + prednisone11 (79)14 (54)0.09
 Cyclophosphamide + prednisone + plasma exchange2 (14)2 (8)0.55
 Methotrexate + prednisone02 (8)0.42
 NA1 (7)8 (30)0.08
Patients with ESRD at last follow-up, n (%)10 (71.4)8 (30.8)0.02
Patients deceased at last follow-up, n (%)6 (42.9)6 (23.1)0.22
  • Values are expressed as numbers of patients, median (range), or mean±SD. Mean arterial pressure was calculated as (2 × diastolic pressure + systolic pressure)/3. AAV, ANCA-associated vasculitis; GPA, granulomatosis with polyangiitis (Wegener granulomatosis); MPA, microscopic polyangiitis; PR3, proteinase-3; MPO, myeloperoxidase; sC3, serum levels of Sc; NA, not available.