The number of participants who needed transfusions, with relative frequency and percentage, and descriptive statistics on the total number of transfusions (number of packed red blood cell units transfused) will be calculated for both the treatment period with ravulizumab and the treatment period with eculizumab.

The number of participants who needed transfusions, with relative frequency and percentage, and descriptive statistics on the number of transfusion sessions (number of days) will be calculated for both the treatment period with ravulizumab and the treatment period with eculizumab.

The proportion of participants without a ≥ 2 g/dL decrease in hemoglobin level in the absence of transfusion will be calculated for both the treatment period with ravulizumab and the treatment period with eculizumab.

BTH is defined as at least 1 new or worsening symptom or sign of intravascular hemolysis (fatigue, hemoglobinuria, abdominal pain, dyspnea, anemia [hemoglobin < 10 g/dL], major adverse vascular event including thrombosis, dysphagia, or erectile dysfunction) in the presence of elevated LDH ≥ 2 * upper limit of normal (ULN) after prior LDH reduction to < 1.5 * ULN while on therapy.

The FACIT-Fatigue is a 13-item questionnaire that assesses self-reported fatigue and its impact upon daily activities and function over the preceding 7 days. Participants will score each item on a 5-point scale. Total scores range from 0 to 52, with a higher score indicating better Quality of Life (QoL).

EORTC is a questionnaire developed to assess the QoL of cancer participants over the preceding 7 days. The questionnaire has 30 questions related to QoL, with the first 28 questions scored on a 4-point scale and the final 2 questions that probe the participant's overall health and QoL scored on a scale of 1 (very poor) to 7 (excellent). Each subscale has a range of 0 to 100%. Thus, a high score for a functional scale represents a high/healthy level of functioning, a high score for the global health status/QoL represents a high QoL, but a high score for a symptom scale/item represents a high level of symptomatology/problem.

PNH-PPQ is a participant-centered approach for evaluating preferences for the treatment of PNH. It contains 11 questions assessing overall treatment preference, evaluating treatment preference according to 9 treatment characteristics, assessing the most important treatment characteristic for participant overall medication preference, and evaluating those same aspects of treatment with ravulizumab.

An AE is any untoward medical occurrence in a participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment. AEs that will occur during the ravulizumab treatment will be collected and will be reported to the Investigator or qualified designee by the participant.

The following medical costs related to PNH sustained by NHS will be collected: specialist visits, pharmacological and non-pharmacological treatments, hospital and emergency rooms admissions, and examinations (by examination type). This will be reported through descriptive statistics and will be appraised considering the quantity of resource consumption by medical resources and its unit costs.

The following costs sustained by the participants related to the infusion visits will be collected: average cost to reach the structure, overall time required for the infusion (time to reach the structure + time of infusion), retirement status of the participant, loss of working days, and need of a caregiver. This will be calculated in terms of the total cost of transport and overall time required for infusion.