This is an observational (study in which the investigators/physicians observe the participant's data and measure their outcomes), international, multicenter (study conducted at multiple sites), cohort (group of individuals with similar characteristics) study. The study consists of prestudy phase, observational phase (2 years), and follow-up phase (1 year). Approximately 50 participants who already receiving ERA therapy for anemia will be observed in this study. In the observational phase, participants' erythropoietin antibody status (positive or negative), clinical progress, treatment for anemia or prevention of anemia, and outcome will be monitored. During this study, enrolled participants will continue to receive standard-of-care treatment for their disease from their individual investigators as before enrollment to this study. Safety evaluations will include assessment of adverse events which will be monitored throughout the study. The total duration of the study will be 3 years.