Participants were considered to have had adequate control of intravascular hemolysis if all of their lactose dehydrogenase (LDH) readings from Week 4 through Week 26 inclusive had values less than or equal to ≤ 1.5 × upper limit of normal (ULN). Participants must have greater than or equal to (≥) 50 percent (%) of scheduled LDH measures in those weeks, must not have had more than (\>) 2 consecutive visits without LDH measures, must not have experienced breakthrough hemolysis, and must not have discontinued study treatment early. Participants were considered not to have had adequate control of intravascular hemolysis if they failed any of these criteria.

Transfusion avoidance was defined as not having received red blood cell (RBC) transfusion during the first 26 weeks. A transfusion was counted only if it was per-protocol, that is, it followed the predefined transfusion algorithm: RBC transfusion due to a post-baseline hemoglobin level \< 9 grams per deciliter (g/dL) (with anemia symptoms) or a post-baseline hemoglobin level \< 7 g/dL (without anemia symptoms).