Risk factors for bleeding in haemato-oncology patients-a nested case-control study: The BITE study protocol (Bleeding In Thrombocytopenia Explained).

Introduction Haemato-oncological patients often receive platelet count driven prophylactic platelet transfusions to prevent bleeding. However, many prophylactically transfused patients still bleed. More knowledge on risk factors for bleeding is therefore needed. This will enable identification of bleeding risk profiles on which future transfusion policy can be optimised. The present BITE study (Bleeding In Thrombocytopenia Explained) aims to identify clinical conditions and biomarkers that are associated with clinically relevant bleeding events. Methods and analysis A matched case–control study nested in a cohort of haemato-oncological patients in the Netherlands. We collect a limited number of variables from all eligible patients, who together form the source population. These patients are followed for the occurrence of clinically relevant bleeding. Consenting patients of the source population form the cohort. Cases from the cohort are frequency matched to selected control patients for the nested case–control study. Of both case and control patients more detailed clinical data is collected. Study population Adult haemato-oncological patients, who are admitted for intensive chemotherapeutic treatment or stem cell transplantation, or who received such treatments in the past and are readmitted for disease or treatment-related adverse events. Statistical analysis Bleeding incidences will be calculated for the total source population, as well as for different subgroups. The association between potential risk factors and the occurrence of bleeding will be analysed using conditional logistic regression, to account for matching of case and control patients. Ethics and dissemination The study was approved by the Medical Research Ethics Committee Leiden Den Haag and Delft, and the Radboudumc Committee on Research Involving Human Subjects. Approval in seven other centres is foreseen. Patients will be asked for written informed consent and data is coded before analyses, according to Dutch privacy law. Results will be published in peer-reviewed journals. Trial registration number NL62499.058.17. NCT03505086; Pre-results.