Meta-analysis of complement levels
The meta-analysis on MAC levels examined 178 patients with active AAV,
148 patients with AAV in remission, and 100 healthy controls. Plasma MAC
levels were significantly higher in the active AAV group compared to
patients in remission (SMD, 1.58, 95% confidence interval (CI),
0.22-2.93) and healthy controls (SMD, 1.50, 95% CI, 0.84-2.17) (Figure
1).
C5a levels were measured in 220 patients with active AAV, 192 patients
with AAV in remission, and 124 healthy controls. Plasma C5a levels were
significantly higher in the active AAV group compared to patients in
remission (SMD, 0.80, 95% CI, 0.33-1.27) and healthy controls (SMD,
1.18, 95% CI, 0.56-1.80) (Figure 2). The remitted group showed higher
plasma C5a levels when compared to controls (SMD, 1.19, 95% CI,
0.27-2.12).
The meta-analysis on C3a levels examined 223 patients with active AAV,
192 patients with AAV in remission, and 124 healthy controls. Plasma C3a
levels had a marginal tendency to be higher in the active AAV group
compared to patients in remission (SMD, 1.35, 95% CI, 0.20-2.51) and
healthy controls (SMD, 1.87, 95% CI, 0.08-3.66), and also in the
remitted AAV groups compared to healthy controls (SMD, 0.73, 95% CI,
0.04-1.41). Significance of C3a regulation was in general borderline
(Figure 3).
Properdin levels were examined and compared in 158 active patients, 128
remitted patients, and 97 healthy controls, but did not show difference
in any of the comparisons (Supplementary figure 2).
Plasma C4d levels were measured in 98 active AAV patients, 90 remitted
AAV patients, and 58 healthy controls. The levels were higher in the
active AAV group compared to healthy controls (SMD, 1.64, 95% CI,
0.34-2.94), and also elevated in AAV patients in remission compared to
controls (SMD, 1.11, 95% CI, 0.31-1.92). C4d levels were not different
between AAV patients in different disease activity states (Supplementary
figure 3).
Plasma factor B levels were examined in 125 patients with active AAV, 82
patients with AAV in remission, and 75 healthy controls. The levels were
higher in the active AAV group compared to controls (SMD, 0.83, 95% CI,
0.53-1.12), and also elevated in AAV patients in remission compared to
controls (SMD, 0.87, 95% CI, 0.39-1.34) (Figure 4). Plasma Bb levels
were investigated in 119 patients with active AAV, 120 patients with AAV
in remission and 65 healthy controls. None of the comparisons
significantly differed (Supplementary figure 4).