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).