TABLE 2.

Interventions and definitions and assessments of bleeding in the included trials

Author, year	Intervention (prophylaxis group)	Control (no prophylaxis group)	Bleeding scale	Definitions of bleeding	Assessment of bleeding
Assir et al., 2013	Platelet transfusion with 1 SD platelet unit (≥5 × 1011 platelets/unit) at study entry	No platelet transfusion	WHO Bleeding scale	Clinically important bleeding: “Severe bleeding” defined as WHO grade 3 and 4 Any bleeding: “New onset bleeding” defined as WHO grade 1–4	Assessor: Not reported Assessment: Patients were assessed for WHO bleeding ever 12 h
Grossman et al., 1980	Platelet transfusion with 1 unit of either SD (4.8 × 1011 platelets/unit) or RD (4.8–6.4 × 1011/unit) platelets to maintain platelet count above 20 × 109/L through all hospital admissions	Platelet transfusions were given for clinically significant bleeding and prior to invasive procedures	Study specific	Clinically important bleeding: “Severe bleeding” Any bleeding: “Mild bleeds” defined as bleeds not requiring active intervention	Assessor: The clinical team performed the assessment Assessment: Daily clinical assessment for signs of bleeding. Fundoscopic examination twice daily when the platelet count was ≤20 × 109/L.
Lye et al., 2017	Supportive care plus 4 units RD (platelets/unit not reported) platelets each day the platelet count was ≤20 × 109/L up until day 7 or discharge If bleeding occurred, platelet transfusions were given at the clinician's discretion in both groups	Supportive care	None	Clinically important bleeding: Defined according to the WHO 2009 dengue guidelines: gum, nose, hemoptysis, hematuria, hematemesis, melaena, melaena or hematemesis‐not controlled by procedure, menorrhagia, menorrhagia or intermenstrual bleeding‐not controlled by progesterone, intermenstrual, hematoma, menses, others Definition of any bleeding: Not reported	Assessor: Not reported Assessment: Daily clinical assessment from day 1 until day 7 or discharge and at day 21 (+/−3)
Murphy et al., 1982	Platelet transfusion with RD (4 units/m2 body surface, platelets/unit not reported) platelets when platelet count was <20 × 109/L irrespective of clinical events. The goal was to maintain a platelet count above 20 × 109/L throughout the patient's course.	Platelet transfusion were given for serious bleeding episodes	None	Definition of clinically important bleeding: Serious bleeding episodes (bleeds) was defined as nasal or oral bleeding requiring packing, gross gastrointestinal bleeding, gross genitourinary bleeding, any central nervous system bleeding, or bleeding requiring red blood cell transfusion. Uncomplicated dermal bleeding was not included. Definition of any bleeding: Not reported	Assessor: Not reported Assessment: Not reported
Sintnicolaas et al., 1981	Platelet transfusion (units/transfusion not reported) with either RD or SD platelets (4 × 1011 platelets/unit) were given to maintain a platelet count above 20 × 109/L. Duration unclear.	Platelet transfusion were given for hemorrhage only	None	Clinically important bleeding: Not reported Any bleeding: Not reported	Assessor: Not reported Assessment: Not reported
Solomon et al., 1978	Platelet transfusion with RD platelet (units/transfusion and dose not reported) whenever platelet count was <20 × 109/L and when clinically significant bleeding occurred throughout the patient's course	Platelet transfusion were given when clinically significant bleeding occurred or when a platelet count of <20 × 109/L was preceded by a decline of 50% in the platelet count during the preceding 24 h	Bleeding was not assessed	Clinically important bleeding: NA Any bleeding: NA	Assessor: NA Assessment: NA
Stanworth et al., 2013	Platelet transfusion with 1 unit of primarily RD (>240 × 109/L platelets/unit) platelets when platelet count was <10 × 109/L and continued daily until the platelet count is greater than 10 × 109/L for 30 days Both groups were transfused with platelets if bleeding of WHO grade 2 or more occurred and prior to invasive procedures or surgery	Platelets transfusions were not prophylactically given irrespective of platelet counts	Modified WHO Bleeding scale	Clinically important bleeding: “Clinical bleeding” was defined as bleeding of a modified WHO grade 2 or higher Any bleeding: Not reported	Assessor: Local research nurse for inpatients and self‐assessment for discharged patients (unblinded) Assessment: Daily standardized bleeding assessment forms were completed each day that the patient was in hospital. Self‐assessed bleeding diaries were completed for patients who were discharged.
Wandt et al., 2012	Platelet transfusion with 1 unit SD (200‐400 × 109 platelets/unit) or RD (>200 × 109/unit) platelets was given when platelet count was ≤10 × 109/L If bleeding continued despite one platelet transfusion, further transfusions was given at the discretion of the treating clinician in both groups	Stable patients were only given platelet transfusion when clinically relevant bleeding occurred. Unstable patients with platelet count was ≤10 × × 109/L were given prophylactic platelet transfusions.	Modified WHO Bleeding scale	Clinically important bleeding: “Clinically relevant bleeding” was defined as a modified WHO grade 2 or higher Any bleeding: Not reported	Assessor: A physician or experienced nurse (unblinded). Two investigators masked to treatment strategy later transformed the bedside bleeding report into modified WHO categories. Assessment: Clinical bleeding assessments was performed twice daily
NCT03713489 (ongoing)	Platelet transfusion with 1 unit of SD (platelets/unit not reported) platelets 3 times for the first week after enrolment, then 2 times a week in the following 3 weeks	Standard care	Bleeding not planned to be assessed	Clinically important bleeding: NA Any bleeding: NA	Assessor: NA Assessment: NA
van de Weerdt et al., (ongoing)	Platelet transfusion with 1 unit of RD (platelets/unit not reported) platelets prior to placement of central catheters The proceduralist can administer rescue platelets at clinical indication in both arms in case of procedure related bleeding	No platelet transfusion	Modified WHO Bleeding scale	Clinically important bleeding: Modified WHO grade 2–4 Any bleeding: Not reported	Assessor: Not reported Assessment: Clinical bleeding will be assessed at 1 h and 24 h post‐procedural. Clinical photos taken at 1 h and 24 h will be used to evaluate size of hematoma in a blinded fashion.

Abbreviations: NA, not applicable; RD, pooled random donor platelets/buffy coat; SD, single donor apheresis platelets; WHO, World Health Organization.