1

Supplemental File 1: Other data collected

Other data collected included: demographics, admission diagnosis, SAPS II, McCabe score, Knaus classification, comorbidities (non-hematologic malignancy, hematologic malignancy, cardiopulmonary bypass within the previous 21 days, transplantation, liver cirrhosis, systemic inflammatory disease, chronic viral hepatitis, human immunodeficiency virus infection, end stage renal disease), presence of infection at the time of TP diagnosis, cristalloids and colloids administered in the 72 hours before TP diagnosis, drug exposure in the 10 previous days with a special emphasis on beta-lactam antibiotics, vancomycin, furosemide, H2-antagonists, heparin and phenytoin, invasive procedure (arterial or venous central catheter, Swan-Ganz catheter, and endotracheal intubation), treatment of organ failures (vasopressors, renal replacement therapy, and mechanical ventilation), major bleeding, blood transfusion requirements, ICU and hospital length of stay, and survival status at ICU and hospital discharge. Daily platelet counts from inclusion to 14 days after inclusion or until ICU discharge if patients were discharged earlier were also recorded.

The decision to use anticoagulant therapy in patients with RRT was left at the discretion of the attending physician. None of the centers used citrate for regional anticoagulation during RRT. As recommended by national guidelines, physicians administered platelet transfusion in patients with a platelet count < 50 X 109/L and who were developing active bleeding or undergoing invasive procedure. In other cases, the decision to infuseplatelets was left at the discretion of the attending physician. Plasma transfusion was administered in patients with a PT <40% not related to vitamin K deficiency, and with active bleeding or invasive procedure.

Supplemental File 2: Definitions

Sepsis, severe sepsis and septic shock were defined according to standard criteria [27].

Disseminated intravascular coagulation (DIC) was defined as the presence of an underlying disorder known to be associated with DIC [28] with a modified ISTH score [29] according to the criteria, with the following cut-off values: I) Platelet counts < 50 x109/L (two points), 50 to 100 x109/l (one point); II) patient prothrombin time (PT) /normal value PT < 50% (two points), 50 to 65% (one point); III) Fibrinogen < 1 g/l (one point); IV) D-dimer > 3 mg/l (three points), 0.5 to 3.0 mg/l (two points). DIC was diagnosed as a sum of five or more points.

The criteria and level of evidence for establishing a causative relationship in drug-induced TP were defined according to George et al[30].

The diagnosis of HIT was either confirmed or excluded by two observers (BS and FT) on the basis of a combination of clinical assessments, the kinetics of platelet count according to heparin exposure and withdrawal, and the results of antigen assay, platelet aggregometry and/or serotonin release. In the event of disagreement between the observers, the presence or absence of HIT was confirmed by a hematologist (AFS).

Folate and vitamin B12 deficiencies were defined by a serum value below the normal range established by each laboratory.

Diagnosis of hemophagocytic syndrome was established on the basis of a modified definition of the Histiocyte Society criteria [31] and included at least four of the following: fever > 7 days, spleen enlargement, bicytopenia without marrow hypoplasia (involving Hb < 9 g/dL, absolute neutrophil count < 1000/μL, platelets < 100 X 109/L), hypertriglyceridemia > 3.0 mmol/L and/or hypofibrinogenemia < 1.5 g/L, serum ferritin > 500 μg/L, and hemophagocytosing macrophages in bone marrow.

Viral-infection associated TP was considered when there was a four-fold increase in virus-specific antibody titer or detection of virus-specific IgM antibody in serum or by serum viral PCR.

Dilutional TP was defined either by the intravenous administration of a volume of > 70 ml/kg of crystalloid, colloid, and plasma within the 24hours before TP diagnosis, or by the administration of massive transfusion, i.e. ≥10 units of packed RBCs, or the transfusion of more than one blood volume [32] within the 24hours before TP.

Transfusion-associated TP was defined by the combination of TP and the presence of antiplatelet antibodies detected within 3 weeks after platelet transfusion.

A decrease in platelet production was considered when the number of megakaryocytes on bone marrow examination was decreased (one or less megakaryocyte per 5 to 10 low-powerfields) [33]

Supplemental File 3: Flow chart of the study

ICU, intensive care unit; LOS, length of stay; TP, Thrombocytopenia

Supplemental File 4:

Daily platelet counts in the 14 days following TP diagnosis in patients with absolute (filled circles) and relative (unfilled circles) TP. The line represents the daily population over time. Data are presented as mean +/- interquartile range.

TP, Thrombocytopenia

Supplemental File 5: Sites of infection and etiologic organisms in thrombocytopenic patients

Variables OverallAbsolute TPRelative TP

N=227N=163N=64

Sites of infectiona,b

Lung128 (56)85 (52)43 (67)

Abdomen59 (26)52 (32)7 (11) e

Otherc70 (31)49 (30)21 (33)

Bloodstream infections50 (22)38 (23)12 (19)

Causative pathogens identifiedd135 (59)98 (60)37 (58)

Gram-positive 55 (24)35 (21)20 (31)

Streptococcus pneumoniae17 (7)13 (8)4 (6)

Other streptococci11 (5)6 (4)5 (8)

Staphylococcus aureus22 (10)13 (8)9 (14)

Other Gram-positive5 (2)3 (2)2 (3)

Gram-negative 77 (34)58 (36)19 (30)

Escherichia coli34 (15)28 (17)6 (9)

Pseudomonas aeruginosa14 (6)9 (6)5 (8)

Klebsiella spp.6 (3)3 (2)3 (5)

Other Gram-negative18 (8)15 (9)3 (5)

Fungi7 (3)6 (4)1 (2)

Expressed as number and (percentage); a, the site of infection was either documented or presumed on the basis of clinical findings; b, patients may have had more than one site of infection; c, other sites of infection included skin, central nervous system, bones and joints and cardiac system; d, patients may have had more than one organism cultured; e, P value between absolute and relative TP patients < 0.05;

Supplemental File 6a: Factors associated with the first severe bleeding event

Model 1

First severe bleeding eventYes NoMultivariate analysis

N=30N=227OR (95% CI)P value

SAPS II score on admission (points) a63 (52-79)55 (43-68) c

Hemophagocytic syndrome b4 (13)6 (3) c

DICb18 (60)82 (36) c

Nadir platelet count <50 x 109/Lb16 (53)48 (21) c2.7 (1.1 - 6.7)0.03

Anticoagulant therapyb10 (33)124 (54) c

Renal replacement therapy b18 (60)68 (30) c

DIC, Disseminated intravascular coagulation; SAPS II, simplified acute physiology score;

a, median and (IQR); b, number and (percentage); c, P <0.05 between patients with and without severe bleeding events.

Supplemental File 6b: Factors associated with the first severe bleeding event

First severe bleeding eventYes NoMultivariate analysis

N=30N=227OR (95% CI)P value

SOFA score on admission a12 (9-16)9 (6-12) c

Hemophagocytic syndrome b4 (13)6 (3) c

DICb18 (60)82 (36) c

Nadir platelet count <50 x 109/Lb16 (53)48 (21) c2.6 (1.0-6.4)0.04

Anticoagulant therapyb10 (33)124 (54) c

Renal replacement therapy b18 (60)68 (30) c

DIC, Disseminated intravascular coagulation; SAPS II, simplified acute physiology score;

a, median and (IQR); b, number and (percentage); c, P <0.05 between patients with and without severe bleeding events.
Supplemental File 7:

Incidence of serious bleeding events and transfusion requirements

Variables OverallAbsolute TPRelative TP

N=301N=208N=93

Serious bleeding event30 (10)26 (13)4 (4)a

Prior to platelet transfusion22 (7)18 (6)4 (4)

Sites of bleeding

Gastro-intestinal10 (3)8 (4)2 (2)

Intra-abdominal4 (1)4 (2)0

Intrathoracic6 (2)6 (3)0

Intracranial4 (1)3 (1)1 (1)

Skin and soft tissue3 (1)2 (1)1 (1)

Genito-urinary3 (1)3 (1)0

Transfusion requirements178 (59)144 (69)34 (37) a

Packed Red Blood Cells160 (53)126 (61)34 (37)a

Platelet transfusion62 (21)62 (30)0a

Fresh frozen plasma54 (18)50 (24)4 (4) a

Expressed as number of patients and (percentage); a, P < 0.05 between absolute and relative TP patients

Supplemental File 8,Factors associated with hospital mortality

Variables Survivors Non-survivorsOR (95% CI)P value

(N=184) (N=117)

Age a60 (15)67 (12) b

SAPS II score on admission a53 (19)63 (21) c1.02 (1.00-1.03)0.001

SOFA score on admission a9 (4)11 (4) c

No functional limitation b72 (39)27 (23) c

Mc Cabe 1b,d129 (70)47 (40) c

Renal replacement therapy b46 (25)60 (51) c

Mechanical ventilation b150 (81)109 (93) c

Use of any vasopressorb116 (63)95 (81) c

Nadir platelet count a97 (65)66 (58) c

Serious bleeding events b11 (6)19 (16) c2.53 (1.10-5.89)0.02

Transfusion requirements b86 (47)92 (79) c

Packed red blood cells b79 (43)81 (69) c

Apheresis platelets b27 (15)35 (30) c

Fresh frozen plasma b19 (10)35 (30) c

Sepsis b131 (71)96 (82) c

Septic shock b56 (30)57 (49) c1.88 (1.13-3.13)0.015

ARDS b11 (6)16 (14) c

Hemophagocytic syndrome b2 (1)1 2(10) c6.91 (1.44-33.2)0.016

ARDS, adult respiratory distress syndrome; DIC, Disseminated intravascular coagulation; SAPS II, simplified acute physiology score; a, mean (+/-SD); b, number and (percentage); c, P <0.05 between hospital survivors and non-survivors patients; d, no severity of underlying disease.

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