The Pilot Optimizing Transfusion Thresholds in Critically-ill Children with Anaemia (P-OpTTICCA) study is a pilot trial for a large pragmatic international parallel open-label non-inferiority randomised controlled trial. The primary outcome of the pilot study is feasibility.

Patients in paediatric intensive care units (PICU) are among the main groups of transfusion recipients. Blood transfusions expose recipients to infectious and non-infectious serious hazards. Despite an increasing number of red blood cell (RBC) transfusion threshold randomised controlled trials (RCT) to date, only one large RCT, the Transfusion Requirement In PICU (TRIPICU) study (Lacroix. N Engl J Med 2007;356:1609-19) informs practice in PICU. This dearth of paediatric data was reiterated by a recent National Heart, Lung and Blood Institutes state of the art symposium. Despite being internally robust, the generalizability of TRIPICU has been questioned given that nearly 90% of critically ill children with haemoglobin (Hb) level ≤ 95 g/L were not enrolled for a range of pre-specified reasons including severity of illness, clinical instability and uncertain physician buy-in, thus threatening broader application of this critical knowledge into practice. Recent data and evidence summarised in systematic reviews support the need to explore the benefits and safety of Hb threshold ≤ 70 g/L for almost all critically ill children, not only those who would have been enrolled in TRIPICU.

We propose an international pilot study that will inform the design of a large pragmatic non-inferiority RCT (termed OpTTICCA) conceived to derive generalizable transfusion guidance for physicians.

Objectives of the pilot-RCT. Specific aims are to:

1. Establish the feasibility of enrolling ≥80% of eligible patients.
2. Document adherence to study intervention ≥80% (restrictive transfusion policy).
3. Assess the incidence rate of the primary outcome measure of the full RCT (new and progressive multiple organ dysfunction syndrome, which includes mortality).
4. Establish the feasibility of using routinely collected clinical information from electronic medical data monitoring system (eMDMS) to enhance cost-efficiency.

In the pilot-RCT, we will enrol 120 patients (20 to 40/site) in PICUs equipped with electronic medical data monitoring system (eMDMS). This trial builds on successful prior RCTs that involved international collaboration and funding (Canada, United Kingdom, France): TRIPICU, Age of Blood Evaluation (ABLE) (Lacroix. N Engl J Med 2015) and Age of Blood in Children in PICU (ABC-PICU study: Tucci et al. Trials 2018). The pilot-RCT will be considered as the vanguard phase of the full OpTTICCA RCT if no important design changes are required.

Expected results. This pilot-RCT will focus on feasibility parameters. It will explore whether we can 1) recruit a much broader eligible patient group, 2) assess protocol adherence, 3) assess the primary outcome measure, and 4) abstract most data electronically. A definitive trial will provide transfusion guidance for many important subgroups in whom evidence is presently lacking including children admitted with bone marrow failure, head injury, some cardiac disorders, and sepsis.

Inclusion Criteria:

• 1. Hemoglobin concentration ≤ 95 g/L, while in PICU
• 2. Not already participating to a randomized controlled trial on hemoglobin threshold to guide red blood cell transfusion practice

Exclusion Criteria:

1. Post conception age ≤ 36 weeks or > 18 years at PICU entry
2. Refusal of consent by patient and/or parent
3. Uncorrected cyanotic cardiac disease, univentricular physiology
4. Sickle cell disease
5. Brain Death
6. Extracorporeal membrane oxygenation (ECMO)

The data of P-OpTTICCA will be integrated in the large trial if possible. This will not be possible if P-OpTTICCA shows that significant changes must be made to the research proposal of the full trial; then the data of participants of P-OpTTICCA will be merged to the data of the full trial using a meta-analysis strategy.