Participants	All people with long‐term bone marrow failure disorders that require platelet transfusions, who are not being actively treated with a haematopoietic stem cell transplant, or intensive chemotherapy. These disorders include myelodysplastic syndromes (MDS), acquired or inherited aplastic anaemia and other congenital bone marrow failure disorders. Due to the inherited nature of a number of bone marrow failure disorders, we will include people of all ages, including neonates.
Experimental intervention	Participants will receive transfusions of platelet concentrates, prepared either from individual units of whole blood or by apheresis to treat bleeding (therapeutic platelet transfusions).
Control intervention	Participants will receive transfusions of platelet concentrates to prevent bleeding in addition to transfusions of platelet concentrates, prepared either from individual units of whole blood or by apheresis to treat bleeding. Prophylactic platelet transfusions are typically given when the platelet count falls below a given trigger level.
Outcomes	Primary outcomes The number of participants with at least one bleeding episode; the total number of days on which bleeding occurred or the total number of bleeding episodes per participant; the number of participants with at least one episode of severe or life‐threatening bleeding. time to first bleeding episode from the start of the study. Secondary outcomes Mortality (all‐causes, secondary to bleeding, and secondary to infection); number of platelet transfusions per participant and number of platelet components per participant; number of red cell transfusions per participant and number of red cell components per participant; platelet transfusion interval; proportion of participants requiring additional interventions to stop bleeding (surgical, medical e.g. tranexamic acid, other blood products e.g. fresh frozen plasma (FFP), cryoprecipitate, fibrinogen) within x days from the start of the study; quality of life assessment using validated tools; transfusion‐related adverse events (transfusion reactions, transfusion‐associated infections, development of platelet antibodies,or platelet refractoriness, thromboembolic events).