Trial Outcomes & Findings for Heparin-Induced Thrombocytopenia - Retrospective Analysis of Data on Incidence and Outcomes Study (NCT NCT01178333)

Results Overview

The mean time to an event is estimated by the area under the survival function. If the largest time is an event time, then the survival function goes to zero at that time, and the mean survival estimate is finite. Otherwise, the mean time cannot be estimated and may lead to a bias.

Recruitment status

COMPLETED

Target enrollment

668 participants

Primary outcome timeframe

From the time that the positive heparin PF-4 antibody test was drawn until hospital discharge or day 45, whichever occurred first.

Results posted on

2015-05-22

Participant Flow

Of 668 consecutive patients with a positive heparin-PF4 ELISA test, 226 were excluded, primarily due to lack of recent heparin exposure. Of 442 eligible patients, 71 had HIT-T, 284 had Isolated HIT and 87 had no HIT.

Participant milestones

Participant milestones
Measure	HIT-T Positive heparin-PF4 ELISA test and a thrombotic event associated with heparin exposure within the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), with or without thrombocytopenia.	Isolated HIT Positive heparin-PF4 ELISA test and a nadir platelet count \<50% of baseline platelet count associated with heparin exposure in the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), without a thrombotic event.	No HIT Positive heparin-PF4 ELISA test with heparin exposure in the preceding 5 days, but not meeting criteria for HIT-T or isolated HIT.
Overall Study STARTED	71	284	87
Overall Study COMPLETED	71	284	87
Overall Study NOT COMPLETED	0	0	0

Reasons for withdrawal

Withdrawal data not reported

Baseline Characteristics

Heparin-Induced Thrombocytopenia - Retrospective Analysis of Data on Incidence and Outcomes Study

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	HIT-T n=71 Participants Positive heparin-PF4 ELISA test and a thrombotic event associated with heparin exposure within the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), with or without thrombocytopenia.	Isolated HIT n=284 Participants Positive heparin-PF4 ELISA test and a nadir platelet count \<50% of baseline platelet count associated with heparin exposure in the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), without a thrombotic event.	No HIT n=87 Participants Positive heparin-PF4 ELISA test with heparin exposure in the preceding 5 days, but not meeting criteria for HIT-T or isolated HIT.	Total n=442 Participants Total of all reporting groups
Age, Continuous	62 years STANDARD_DEVIATION 16 • n=93 Participants	59 years STANDARD_DEVIATION 18 • n=4 Participants	60 years STANDARD_DEVIATION 19 • n=27 Participants	60 years STANDARD_DEVIATION 18 • n=483 Participants
Sex: Female, Male Female	39 Participants n=93 Participants	144 Participants n=4 Participants	40 Participants n=27 Participants	223 Participants n=483 Participants
Sex: Female, Male Male	32 Participants n=93 Participants	140 Participants n=4 Participants	47 Participants n=27 Participants	219 Participants n=483 Participants
Baseline Platelet Count	282 x 10^9/L STANDARD_DEVIATION 268 • n=93 Participants	270 x 10^9/L STANDARD_DEVIATION 149 • n=4 Participants	215 x 10^9/L STANDARD_DEVIATION 172 • n=27 Participants	261 x 10^9/L STANDARD_DEVIATION 158 • n=483 Participants
Heparin exposure this admission before Day 0: use (or non-use) of unfractionated heparin (UFH) Use of unfractionated heparin	67 participants n=93 Participants	263 participants n=4 Participants	79 participants n=27 Participants	409 participants n=483 Participants
Heparin exposure this admission before Day 0: use (or non-use) of unfractionated heparin (UFH) Non-use of unfractionated heparin	4 participants n=93 Participants	21 participants n=4 Participants	8 participants n=27 Participants	33 participants n=483 Participants
Heparin exposure this admission before Day 0: use (or non-use) of low molecular weight heparin Use of low molecular weight heparin	15 participants n=93 Participants	48 participants n=4 Participants	11 participants n=27 Participants	74 participants n=483 Participants
Heparin exposure this admission before Day 0: use (or non-use) of low molecular weight heparin Non-use of low molecular weight heparin	56 participants n=93 Participants	236 participants n=4 Participants	76 participants n=27 Participants	368 participants n=483 Participants
Heparin-PF4 (platelet factor 4) OD (optical density) test results Less than 1.0	34 participants n=93 Participants	163 participants n=4 Participants	61 participants n=27 Participants	258 participants n=483 Participants
Heparin-PF4 (platelet factor 4) OD (optical density) test results Greater than or equal to 1.0	37 participants n=93 Participants	120 participants n=4 Participants	26 participants n=27 Participants	183 participants n=483 Participants
Heparin-PF4 (platelet factor 4) OD (optical density) test results Missing	0 participants n=93 Participants	1 participants n=4 Participants	0 participants n=27 Participants	1 participants n=483 Participants
Admitting service CV/thoracic surgery	18 participants n=93 Participants	78 participants n=4 Participants	18 participants n=27 Participants	114 participants n=483 Participants
Admitting service Orthopedic surgery	2 participants n=93 Participants	9 participants n=4 Participants	4 participants n=27 Participants	15 participants n=483 Participants
Admitting service Other surgery	15 participants n=93 Participants	33 participants n=4 Participants	8 participants n=27 Participants	56 participants n=483 Participants
Admitting service Medicine	36 participants n=93 Participants	161 participants n=4 Participants	56 participants n=27 Participants	253 participants n=483 Participants
Admitting service Missing	0 participants n=93 Participants	3 participants n=4 Participants	1 participants n=27 Participants	4 participants n=483 Participants

PRIMARY outcome

Timeframe: From the time that the positive heparin PF-4 antibody test was drawn until hospital discharge or day 45, whichever occurred first.

The mean time to an event is estimated by the area under the survival function. If the largest time is an event time, then the survival function goes to zero at that time, and the mean survival estimate is finite. Otherwise, the mean time cannot be estimated and may lead to a bias.

Outcome measures

Outcome measures
Measure	HIT-T n=71 Participants Positive heparin-PF4 ELISA test and a thrombotic event associated with heparin exposure within the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), with or without thrombocytopenia.	Isolated HIT n=284 Participants Positive heparin-PF4 ELISA test and a nadir platelet count \<50% of baseline platelet count associated with heparin exposure in the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), without a thrombotic event.	No HIT n=87 Participants Positive heparin-PF4 ELISA test with heparin exposure in the preceding 5 days, but not meeting criteria for HIT-T or isolated HIT.
Time to Occurrence of a Composite Triple Endpoint Consisting of Death, Limb Amputation/Gangrene, and New Thrombosis	17.5 days Standard Error 1.66	27.8 days Standard Error 1.30	31.4 days Standard Error 2.67

PRIMARY outcome

Timeframe: From the time that the positive heparin PF-4 antibody test was drawn until hospital discharge or day 45, whichever occurred first.

The median survival time is reported by each group for the time to occurrence of a composite triple endpoint consisting of death, limb amputation/gangrene, and new thrombosis.

Outcome measures

Outcome measures
Measure	HIT-T n=71 Participants Positive heparin-PF4 ELISA test and a thrombotic event associated with heparin exposure within the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), with or without thrombocytopenia.	Isolated HIT n=284 Participants Positive heparin-PF4 ELISA test and a nadir platelet count \<50% of baseline platelet count associated with heparin exposure in the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), without a thrombotic event.	No HIT n=87 Participants Positive heparin-PF4 ELISA test with heparin exposure in the preceding 5 days, but not meeting criteria for HIT-T or isolated HIT.
Time to Occurrence of a Composite Triple Endpoint Consisting of Death, Limb Amputation/Gangrene, and New Thrombosis	13.0 days Interval 9.0 to Due to lack of events, the upper interval of the median survival time could not be estimated.	33.0 days Interval 25.0 to Due to lack of events, the upper interval of the median survival time could not be estimated.	NA days Interval 29.0 to Due to lack of events, the median survival time and the upper interval could not be estimated.

SECONDARY outcome

Timeframe: From the time the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first

The mean time to an event is estimated by the area under the survival function. If the largest time is an event time, then the survival function goes to zero at that time, and the mean survival estimate is finite. Otherwise, the mean time cannot be estimated and may lead to a bias.

Outcome measures

Outcome measures
Measure	HIT-T n=71 Participants Positive heparin-PF4 ELISA test and a thrombotic event associated with heparin exposure within the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), with or without thrombocytopenia.	Isolated HIT n=284 Participants Positive heparin-PF4 ELISA test and a nadir platelet count \<50% of baseline platelet count associated with heparin exposure in the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), without a thrombotic event.	No HIT n=87 Participants Positive heparin-PF4 ELISA test with heparin exposure in the preceding 5 days, but not meeting criteria for HIT-T or isolated HIT.
Time to Death	23.6 days Standard Error 1.43	35.4 days Standard Error 1.11	34.5 days Standard Error 2.64

SECONDARY outcome

Timeframe: From the time the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first

The median survival time is reported by each group for the time to death.

Outcome measures

Outcome measures
Measure	HIT-T n=71 Participants Positive heparin-PF4 ELISA test and a thrombotic event associated with heparin exposure within the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), with or without thrombocytopenia.	Isolated HIT n=284 Participants Positive heparin-PF4 ELISA test and a nadir platelet count \<50% of baseline platelet count associated with heparin exposure in the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), without a thrombotic event.	No HIT n=87 Participants Positive heparin-PF4 ELISA test with heparin exposure in the preceding 5 days, but not meeting criteria for HIT-T or isolated HIT.
Time to Death	31.0 days Interval 23.0 to Due to lack of events, the upper interval of the median survival time could not be estimated.	NA days Due to lack of events, the median survival time and 95% confidence interval could not be estimated.	NA days Interval 29.0 to Due to lack of events, the median survival time and the upper interval could not be estimated.

SECONDARY outcome

Timeframe: From the time the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first

Due to the small number of events, the median or mean survival time could not be defined. Therefore, the number of subjects with limb amputation or limb gangrene was reported in "Outcome Measure Data Table".

Outcome measures

Outcome measures
Measure	HIT-T n=71 Participants Positive heparin-PF4 ELISA test and a thrombotic event associated with heparin exposure within the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), with or without thrombocytopenia.	Isolated HIT n=284 Participants Positive heparin-PF4 ELISA test and a nadir platelet count \<50% of baseline platelet count associated with heparin exposure in the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), without a thrombotic event.	No HIT n=87 Participants Positive heparin-PF4 ELISA test with heparin exposure in the preceding 5 days, but not meeting criteria for HIT-T or isolated HIT.
Time to Occurrence of Limb Amputation or Limb Gangrene	5 participants	6 participants	1 participants

SECONDARY outcome

Timeframe: From the time the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first

The mean time to an event is estimated by the area under the survival function. If the largest time is an event time, then the survival function goes to zero at that time, and the mean survival estimate is finite. Otherwise, the mean time cannot be estimated and may lead to a bias. However, the median survival times could not be defined for all three groups, so the mean time was reported in "Outcome Measure Data Table".

Outcome measures

Outcome measures
Measure	HIT-T n=71 Participants Positive heparin-PF4 ELISA test and a thrombotic event associated with heparin exposure within the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), with or without thrombocytopenia.	Isolated HIT n=284 Participants Positive heparin-PF4 ELISA test and a nadir platelet count \<50% of baseline platelet count associated with heparin exposure in the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), without a thrombotic event.	No HIT n=87 Participants Positive heparin-PF4 ELISA test with heparin exposure in the preceding 5 days, but not meeting criteria for HIT-T or isolated HIT.
Time to Occurrence of Radiographically Confirmed Thromboembolism	11.1 days Standard Error 0.48	26.1 days Standard Error 0.74	5.74 days Standard Error 0.11

SECONDARY outcome

Timeframe: From the time that the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first

The mean time to an event is estimated by the area under the survival function. If the largest time is an event time, then the survival function goes to zero at that time, and the mean survival estimate is finite. Otherwise, the mean time cannot be estimated and may lead to a bias.

Outcome measures

Outcome measures
Measure	HIT-T n=71 Participants Positive heparin-PF4 ELISA test and a thrombotic event associated with heparin exposure within the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), with or without thrombocytopenia.	Isolated HIT n=284 Participants Positive heparin-PF4 ELISA test and a nadir platelet count \<50% of baseline platelet count associated with heparin exposure in the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), without a thrombotic event.	No HIT n=87 Participants Positive heparin-PF4 ELISA test with heparin exposure in the preceding 5 days, but not meeting criteria for HIT-T or isolated HIT.
Time to Occurrence of Major Bleeding	15.6 days Standard Error 1.54	26.5 days Standard Error 1.36	17.2 days Standard Error 0.97

SECONDARY outcome

Timeframe: From the time that the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first

The median survival time is reported by each group for the time to occurrence of major bleeding.

Outcome measures

Outcome measures
Measure	HIT-T n=71 Participants Positive heparin-PF4 ELISA test and a thrombotic event associated with heparin exposure within the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), with or without thrombocytopenia.	Isolated HIT n=284 Participants Positive heparin-PF4 ELISA test and a nadir platelet count \<50% of baseline platelet count associated with heparin exposure in the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), without a thrombotic event.	No HIT n=87 Participants Positive heparin-PF4 ELISA test with heparin exposure in the preceding 5 days, but not meeting criteria for HIT-T or isolated HIT.
Time to Occurrence of Major Bleeding	17.0 days Interval 8.0 to 28.0	36.0 days Interval 31.0 to Due to lack of events, the upper interval of median survival time could not be estimated.	NA days Interval 16.0 to Due to lack of events, the median survival time and the upper interval could not be estimated.

SECONDARY outcome

Timeframe: From the date 5 days before the positive heparin PF-4 antibody test was drawn to the date it was drawn

Proportion of subjects who, at the time the positive heparin PF-4 antibody test was drawn, were in each of the following categories: * Group 1: Those with thrombosis and or without thrombocytopenia (HIT-T): 16% of 442 subjects. * Group 2: Those with thrombocytopenia but not thrombosis (Isolated HIT): 64% of 442 subjects. * Group 3: Those with neither thrombocytopenia nor thrombosis (Neither HIT-T nor Isolated HIT): 20% of 442 subjects.

Outcome measures

Outcome measures
Measure	HIT-T n=71 Participants Positive heparin-PF4 ELISA test and a thrombotic event associated with heparin exposure within the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), with or without thrombocytopenia.	Isolated HIT n=284 Participants Positive heparin-PF4 ELISA test and a nadir platelet count \<50% of baseline platelet count associated with heparin exposure in the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), without a thrombotic event.	No HIT n=87 Participants Positive heparin-PF4 ELISA test with heparin exposure in the preceding 5 days, but not meeting criteria for HIT-T or isolated HIT.
Proportion of Subjects With HIT With Thrombosis (HIT-T) and Isolated HIT	71 participants	284 participants	87 participants

SECONDARY outcome

Timeframe: Hospital admission to date the positive heparin PF-4 antibody test was drawn, or 28 days prior to the date it was drawn, whichever is later, through the date it was drawn

Two types of heparins are commonly used as anticoagulants - unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH). UFH has been used for the prevention and treatment of thrombosis for several decades.

Outcome measures

Outcome measures
Measure	HIT-T n=71 Participants Positive heparin-PF4 ELISA test and a thrombotic event associated with heparin exposure within the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), with or without thrombocytopenia.	Isolated HIT n=284 Participants Positive heparin-PF4 ELISA test and a nadir platelet count \<50% of baseline platelet count associated with heparin exposure in the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), without a thrombotic event.	No HIT n=87 Participants Positive heparin-PF4 ELISA test with heparin exposure in the preceding 5 days, but not meeting criteria for HIT-T or isolated HIT.
Type of Heparin Exposure - Unfractionated Heparin (UFH) Number of subjects with heparin exposure:UFH	67 participants	263 participants	79 participants
Type of Heparin Exposure - Unfractionated Heparin (UFH) Number of subjects without heparin exposure:UFH	4 participants	21 participants	8 participants

SECONDARY outcome

Timeframe: Hospital admission to date the positive heparin PF-4 antibody test was drawn, or 28 days prior to the date it was drawn, whichever is later, through the date it was drawn

Two types of heparins are commonly used as anticoagulants - unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH). LMWHs are derived from UFH by depolymerization. Each LMWH product has a specific molecular weight distribution that determines its anticoagulant activity and duration of action.

Outcome measures

Outcome measures
Measure	HIT-T n=71 Participants Positive heparin-PF4 ELISA test and a thrombotic event associated with heparin exposure within the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), with or without thrombocytopenia.	Isolated HIT n=284 Participants Positive heparin-PF4 ELISA test and a nadir platelet count \<50% of baseline platelet count associated with heparin exposure in the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), without a thrombotic event.	No HIT n=87 Participants Positive heparin-PF4 ELISA test with heparin exposure in the preceding 5 days, but not meeting criteria for HIT-T or isolated HIT.
Type of Heparin Exposure - Low Molecular Weight Heparin (LMWH) Number of subjects with heparin exposure:LMWH	15 participants	48 participants	11 participants
Type of Heparin Exposure - Low Molecular Weight Heparin (LMWH) Number of subjects without heparin exposure:LMWH	56 participants	236 participants	76 participants

SECONDARY outcome

Timeframe: From the time the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first

Population: There was one missing data for optical density test results in Isolated HIT group. Therefore, 283 subjects were used for Isolated HIT group.

Heparin PF-4 (platelet factor 4) optical density (OD) test results were the dichotomous outcome (\<1.0 vs. \>=1.0). Clinical diagnosis was three groups (HIT-T, Isolated HIT and No HIT). The Heparin PF-4 optical density test looks for antibodies to complexes of heparin combined with platelet factor 4. Higher optical density indicates higher antibody concentration. We could say that generally OD values above 0.4 are considered a positive result, and that the higher the OD, the greater the concentration of antibodies in the patient's blood.

Outcome measures

Outcome measures
Measure	HIT-T n=71 Participants Positive heparin-PF4 ELISA test and a thrombotic event associated with heparin exposure within the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), with or without thrombocytopenia.	Isolated HIT n=283 Participants Positive heparin-PF4 ELISA test and a nadir platelet count \<50% of baseline platelet count associated with heparin exposure in the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), without a thrombotic event.	No HIT n=87 Participants Positive heparin-PF4 ELISA test with heparin exposure in the preceding 5 days, but not meeting criteria for HIT-T or isolated HIT.
Relationship of the Heparin PF-4 (Platelet Factor 4) Antibody Titer to the Clinical Diagnosis Optical density Results less than 1.0	34 participants	163 participants	61 participants
Relationship of the Heparin PF-4 (Platelet Factor 4) Antibody Titer to the Clinical Diagnosis Optical density Results greater or equal to 1.0	37 participants	120 participants	26 participants

SECONDARY outcome

Timeframe: From the time the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first

Heparin PF-4 optical density (OD) test results were the dichotomous outcome (\<1.0 vs. \>=1.0). Nadir Platelet Count (x10\^9 / L) was used for the degree of thrombocytopenia. The Heparin PF-4 optical density test looks for antibodies to complexes of heparin combined with platelet factor 4. Higher optical density indicates higher antibody concentration. We could say that generally OD values above 0.4 are considered a positive result, and that the higher the OD, the greater the concentration of antibodies in the patient's blood.

Outcome measures

Outcome measures
Measure	HIT-T n=258 Participants Positive heparin-PF4 ELISA test and a thrombotic event associated with heparin exposure within the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), with or without thrombocytopenia.	Isolated HIT n=183 Participants Positive heparin-PF4 ELISA test and a nadir platelet count \<50% of baseline platelet count associated with heparin exposure in the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), without a thrombotic event.	No HIT Positive heparin-PF4 ELISA test with heparin exposure in the preceding 5 days, but not meeting criteria for HIT-T or isolated HIT.
Relationship of the Heparin PF-4 Antibody Titer to the Degree of Thrombocytopenia	87.7 X10^9 / L Standard Deviation 92.4	83.1 X10^9 / L Standard Deviation 76.4	—

SECONDARY outcome

Timeframe: From the time the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first

Heparin PF-4 OD test results were the dichotomous outcome (\<1.0 vs. \>=1.0). Primary endpoint was the composite endpoint of death, limb amputation/gangrene, or new thrombosis.

Outcome measures

Outcome measures
Measure	HIT-T n=258 Participants Positive heparin-PF4 ELISA test and a thrombotic event associated with heparin exposure within the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), with or without thrombocytopenia.	Isolated HIT n=183 Participants Positive heparin-PF4 ELISA test and a nadir platelet count \<50% of baseline platelet count associated with heparin exposure in the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), without a thrombotic event.	No HIT Positive heparin-PF4 ELISA test with heparin exposure in the preceding 5 days, but not meeting criteria for HIT-T or isolated HIT.
Relationship of the Heparin PF-4 Antibody Titer to the Primary Endpoint Composite endpoint	85 participants	66 participants	—
Relationship of the Heparin PF-4 Antibody Titer to the Primary Endpoint No composite endpoint	173 participants	117 participants	—

SECONDARY outcome

Timeframe: From the time that the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first

Types of treatment (direct thrombin inhibitor, fondaparinux, warfarin, no treatment) provided to subjects in hospital

Outcome measures

Outcome measures
Measure	HIT-T n=71 Participants Positive heparin-PF4 ELISA test and a thrombotic event associated with heparin exposure within the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), with or without thrombocytopenia.	Isolated HIT n=284 Participants Positive heparin-PF4 ELISA test and a nadir platelet count \<50% of baseline platelet count associated with heparin exposure in the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), without a thrombotic event.	No HIT n=87 Participants Positive heparin-PF4 ELISA test with heparin exposure in the preceding 5 days, but not meeting criteria for HIT-T or isolated HIT.
Use of Treatment (Non-heparin Anticoagulant) Used in Hospital Number of subjects with treatment in hospital	58 participants	167 participants	43 participants
Use of Treatment (Non-heparin Anticoagulant) Used in Hospital Number of subjects without treatment in hospital	13 participants	117 participants	44 participants

SECONDARY outcome

Timeframe: From the time that the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first

Outcome measures

Outcome measures
Measure	HIT-T n=71 Participants Positive heparin-PF4 ELISA test and a thrombotic event associated with heparin exposure within the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), with or without thrombocytopenia.	Isolated HIT n=284 Participants Positive heparin-PF4 ELISA test and a nadir platelet count \<50% of baseline platelet count associated with heparin exposure in the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), without a thrombotic event.	No HIT n=87 Participants Positive heparin-PF4 ELISA test with heparin exposure in the preceding 5 days, but not meeting criteria for HIT-T or isolated HIT.
Use of Treatment (Non-heparin Anticoagulant) Used at the Time of Discharge Number of subjects with treatment at discharge	57 participants	159 participants	39 participants
Use of Treatment (Non-heparin Anticoagulant) Used at the Time of Discharge Number of subjects with no treatment at discharge	14 participants	125 participants	48 participants

SECONDARY outcome

Timeframe: From the time that the nadir platelet count was drawn until hospital discharge, death, or day 45, whichever occurred first

Outcome measures

Outcome measures
Measure	HIT-T n=52 Participants Positive heparin-PF4 ELISA test and a thrombotic event associated with heparin exposure within the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), with or without thrombocytopenia.	Isolated HIT n=249 Participants Positive heparin-PF4 ELISA test and a nadir platelet count \<50% of baseline platelet count associated with heparin exposure in the preceding 5 days (and with the onset of a platelet count drop of \>15% beginning within 5-10 days after starting heparin), without a thrombotic event.	No HIT n=40 Participants Positive heparin-PF4 ELISA test with heparin exposure in the preceding 5 days, but not meeting criteria for HIT-T or isolated HIT.
Time to Platelet Recovery, Among Subjects With a Low Platelet Count When the Positive PF4 Antibody Test Was Drawn	5.16 days Standard Error 0.92	5.16 days Standard Error 0.38	2.96 days Standard Error 0.33

Adverse Events

HIT-T

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Isolated HIT

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

No HIT

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Serious adverse events

Adverse event data not reported

Other adverse events

Adverse event data not reported

Additional Information

Dr. Susan Assmann, Principal Research Scientist

New England Research Institutes

Phone: 617-972-3048

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee All publications and presentations resulting from studies from the TMH Network must be approved by the Publications and Presentations Committee before submission. The Sponsor (NERI) and funding agency (NHLBI) both are represented on the P\&P Committee along with Network Investigators. Members of the P\&P Committee can recommend changes to publications.
Publication restrictions are in place

Restriction type: OTHER