Mean (95% CI) free C5 concentrations in the ravulizumab and eculizumab groups over time. Free C5 levels were assessed using a Gyros-based fluorescence assay in patients who received ravulizumab and an electrochemiluminescent immunoassay in patients who received eculizumab; 3 patients in the ravulizumab group and 8 in the eculizumab group had day 1 samples excluded because the samples were considered biologically implausible. Free C5 levels <0.5 µg/mL are associated with complete inhibition of C5 activity. Data from days 1, 15, 71, and 127 are from predose and end of infusion for both treatment groups, whereas at days 8, 22, 29, 43, 57, 85, 99, 113, 141, 155, and 169, the data are from any time for the ravulizumab group and predose for the eculizumab group; and at day 183, data are from end of the randomized treatment period for both treatment groups. BL, baseline (the last nonmissing assessment value before first dose of study drug).