The BITE study - Bleeding In Thrombocytopenia Explained: A nationwide epidemiological and laboratory case cohort study investigating risk factors for bleeding in hemato-oncology patients

Hemato-oncological patients treated with intensive chemotherapy receive
prophylactic platelet transfusions to prevent bleeding events as soon as their
platelet counts drop below 10 x109/L. This platelet count based prophylactic
transfusion strategy, however, is both inefficient and often not needed. This
is reflected in the high percentage of patients with bleeding despite this
strategy (43%), and the high percentage of patients who do not bleed without
this strategy (50%). Solely platelet count therefore is not a good predictor
for bleeding. Identification of new risk factors and confirmation of already
suspected risk factors is essential, and should lead to better prediction and
prevention of bleeding. Patients with a high risk profile could be given more
effective haemostatic treatments including more efficient transfusion
strategies. On the other hand one could consider omitting prophylactic
transfusions to low risk patients and conditions. Furthermore, more knowledge
about the pathophysiology of bleeding in hemato-oncology patients is needed.

- Identify hemato-oncology patients and conditions with a high versus a low
bleeding risk, by epidemiological research and a short questionnaire.
- Investigate the association of bleeding related biomarkers with bleeding.

Case cohort study, consisting of two parts: an epidemiologically research
including short questionnaire (for all patients that meet the inclusion
criteria), part B additional blood and urine sampling (only for patients who
are admitted for chemotherapy or stem cell transplantation).

The epidemiological part of the study does not have burden or health risks:
comparison of standard available data between bleeding and non-bleeding
patients makes this a non-WMO part of the study, since there is no invasive
intervention. The 10-15 minutes questionnaire in this respect is not considered
as a burden.
The laboratory part of the study only applies for a subgroup of the included
patients and falls under the scope of the WMO. The intervention is the
additional to regularly performed citrate anticoagulated blood sampling
(maximum 10 samples of 10-15 cc in 4 weeks), as well as weekly urine sampling.
Both are considered a minor burden for participants, and the risk of additional
blood sampling at regular sampling moments is negligible. Finally, all
BITE-study activities in both study parts will not have any consequences on the
treatment or monitoring of patients.