The aim of this non-interventional secondary use of data study is to evaluate hematological response in patients with paroxysmal nocturnal hemoglobinuria and anemia in the 6-month period after initiation of anti-C5 antibody treatment using real-world data obtained from multiple datasets. The results will be used to contextualize results from the APPOINT-PNH (NCT04820530) trial with iptacopan.

Inclusion Criteria:

1. Incident users of anti-C5 antibody treatment (i.e., first use of anti-C5 antibody with no evidence of use prior to that)
2. Confirmed clinical diagnosis of PNH (including PNH clone size >10% in RBC percent/white blood cell (WBC) percent)
3. Adult patients ≥18 years of age
4. Baseline Hb <10 g/dL.

Exclusion Criteria:

Patients who met any of the following criteria were not eligible for inclusion.

1. Bone marrow transplantation within one year prior to initiating anti-C5 treatment
2. Hereditary complement deficiency
3. Reticulocyte count <60x10^9/L.
4. Pregnancy

The real-world cohort consists of patients with diagnosis of paroxysmal nocturnal hemoglobinuria and anemia initiating anti-C5 therapy. Patient data originate from the Hôpital Saint-Louis, France and St. James's University Hospital, Leeds, United Kingdom.