Heparin Induced Thrombocytopenia
Conditions
Keywords
Thrombocytopenia, Heparin
Brief summary
HIT-RADIO is a study of patients who had a positive heparin PF-4 antibody test between 1/21/2008 and 9/25/2008 at selected hospitals. The study will collect and analyse information that is already in the patients' medical records. Information about laboratory values (such as platelet counts), treatments (such as medications), and outcomes (such as blood clots, amputation, and death) will be included.
Detailed description
HIT-RADIO is a retrospective chart-review study of patients who had a positive heparin PF-4 antibody test between 1/21/2008 and 9/25/2008 at selected hospitals associated with the Transfusion Medicine/Hemostasis Clinical Trials Network . Heparin-induced thrombocytopenia (HIT) is a major complication of the administration of heparin and can result in life-threatening thrombosis with or without thrombocytopenia (HIT-T) or can produce thrombocytopenia without clinically symptomatic thrombosis (isolated HIT). Isolated heparin-induced thrombocytopenia is defined as a fall in platelet count associated with a positive heparin PF-4 antibody test, in the absence of clinically overt thrombosis. While the treatment of HIT-T (HIT with thrombosis) with anticoagulation is well established, the risks and treatment of isolated HIT are unclear. It is anticipated that this data analysis will provide a current overview of the implications of a positive heparin PF-4 antibody test in clinical practice. It should determine the percentage of positive heparin PF-4 antibody tests that are associated with thrombocytopenia and thrombosis (HIT-T) or isolated HIT at diagnosis and the subsequent major clinical outcomes of death, limb amputation/gangrene, and new thrombosis. No snapshot of such HIT patients has been conducted in the past decade and the results will be important in assessing the impact of HIT in current medical care as well as documenting current treatment strategies.
Interventions
None listed
Sponsors
National Heart, Lung, and Blood Institute (NHLBI)
Carelon Research
Study design
Observational model
CASE_ONLY
Time perspective
RETROSPECTIVE
Eligibility
Sex/Gender
ALL
Healthy volunteers
No
Inclusion criteria
* All subjects with a positive heparin PF-4 antibody test occurring between 1/21/2008 and 9/25/2008 * Medical record available for the admission during which the positive heparin PF-4 antibody test was obtained
Exclusion criteria
* None
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Time to Occurrence of a Composite Triple Endpoint Consisting of Death, Limb Amputation/Gangrene, and New Thrombosis | 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. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Time to Occurrence of Limb Amputation or Limb Gangrene | 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. |
| Time to Occurrence of Radiographically Confirmed Thromboembolism | 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. |
| Time to Occurrence of Major Bleeding | 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. |
| Proportion of Subjects With HIT With Thrombosis (HIT-T) and Isolated HIT | 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. |
| Type of Heparin Exposure - Unfractionated Heparin (UFH) | 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. |
| Type of Heparin Exposure - Low Molecular Weight Heparin (LMWH) | 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. |
| Time to Death | 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. |
| Relationship of the Heparin PF-4 Antibody Titer to the Degree of Thrombocytopenia | 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. |
| Relationship of the Heparin PF-4 Antibody Titer to the Primary Endpoint | 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. |
| Use of Treatment (Non-heparin Anticoagulant) Used in Hospital | 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 |
| Use of Treatment (Non-heparin Anticoagulant) Used at the Time of Discharge | From the time that the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first | — |
| Time to Platelet Recovery, Among Subjects With a Low Platelet Count When the Positive PF4 Antibody Test Was Drawn | From the time that the nadir platelet count was drawn until hospital discharge, death, or day 45, whichever occurred first | — |
| Relationship of the Heparin PF-4 (Platelet Factor 4) Antibody Titer to the Clinical Diagnosis | 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 (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. |
Countries
United States
Participant flow
Recruitment details
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.
Participants by arm
| Arm | Count |
|---|---|
| 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. | 71 |
| 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. | 284 |
| 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. | 87 |
| Total | 442 |
Baseline characteristics
| Characteristic | No HIT | Isolated HIT | Total | HIT-T |
|---|---|---|---|---|
| Admitting service CV/thoracic surgery | 18 participants | 78 participants | 114 participants | 18 participants |
| Admitting service Medicine | 56 participants | 161 participants | 253 participants | 36 participants |
| Admitting service Missing | 1 participants | 3 participants | 4 participants | 0 participants |
| Admitting service Orthopedic surgery | 4 participants | 9 participants | 15 participants | 2 participants |
| Admitting service Other surgery | 8 participants | 33 participants | 56 participants | 15 participants |
| Age, Continuous | 60 years STANDARD_DEVIATION 19 | 59 years STANDARD_DEVIATION 18 | 60 years STANDARD_DEVIATION 18 | 62 years STANDARD_DEVIATION 16 |
| Baseline Platelet Count | 215 x 10^9/L STANDARD_DEVIATION 172 | 270 x 10^9/L STANDARD_DEVIATION 149 | 261 x 10^9/L STANDARD_DEVIATION 158 | 282 x 10^9/L STANDARD_DEVIATION 268 |
| Heparin exposure this admission before Day 0: use (or non-use) of low molecular weight heparin Non-use of low molecular weight heparin | 76 participants | 236 participants | 368 participants | 56 participants |
| Heparin exposure this admission before Day 0: use (or non-use) of low molecular weight heparin Use of low molecular weight heparin | 11 participants | 48 participants | 74 participants | 15 participants |
| Heparin exposure this admission before Day 0: use (or non-use) of unfractionated heparin (UFH) Non-use of unfractionated heparin | 8 participants | 21 participants | 33 participants | 4 participants |
| Heparin exposure this admission before Day 0: use (or non-use) of unfractionated heparin (UFH) Use of unfractionated heparin | 79 participants | 263 participants | 409 participants | 67 participants |
| Heparin-PF4 (platelet factor 4) OD (optical density) test results Greater than or equal to 1.0 | 26 participants | 120 participants | 183 participants | 37 participants |
| Heparin-PF4 (platelet factor 4) OD (optical density) test results Less than 1.0 | 61 participants | 163 participants | 258 participants | 34 participants |
| Heparin-PF4 (platelet factor 4) OD (optical density) test results Missing | 0 participants | 1 participants | 1 participants | 0 participants |
| Sex: Female, Male Female | 40 Participants | 144 Participants | 223 Participants | 39 Participants |
| Sex: Female, Male Male | 47 Participants | 140 Participants | 219 Participants | 32 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk | EG002 affected / at risk |
|---|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — | — / — |
| other Total, other adverse events | 0 / 0 | 0 / 0 | 0 / 0 |
| serious Total, serious adverse events | 0 / 0 | 0 / 0 | 0 / 0 |
Outcome results
Primary
Time to Occurrence of a Composite Triple Endpoint Consisting of Death, Limb Amputation/Gangrene, and New Thrombosis
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.
Time frame: From the time that the positive heparin PF-4 antibody test was drawn until hospital discharge or day 45, whichever occurred first.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| HIT-T | Time to Occurrence of a Composite Triple Endpoint Consisting of Death, Limb Amputation/Gangrene, and New Thrombosis | 17.5 days | Standard Error 1.66 |
| Isolated HIT | Time to Occurrence of a Composite Triple Endpoint Consisting of Death, Limb Amputation/Gangrene, and New Thrombosis | 27.8 days | Standard Error 1.3 |
| No HIT | Time to Occurrence of a Composite Triple Endpoint Consisting of Death, Limb Amputation/Gangrene, and New Thrombosis | 31.4 days | Standard Error 2.67 |
p-value: 0.00395% CI: [1.35, 4.55]Regression, Cox
p-value: 0.0795% CI: [0.96, 2.85]Regression, Cox
Primary
Time to Occurrence of a Composite Triple Endpoint Consisting of Death, Limb Amputation/Gangrene, and New Thrombosis
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.
Time frame: From the time that the positive heparin PF-4 antibody test was drawn until hospital discharge or day 45, whichever occurred first.
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| HIT-T | Time to Occurrence of a Composite Triple Endpoint Consisting of Death, Limb Amputation/Gangrene, and New Thrombosis | 13.0 days |
| Isolated HIT | Time to Occurrence of a Composite Triple Endpoint Consisting of Death, Limb Amputation/Gangrene, and New Thrombosis | 33.0 days |
| No HIT | Time to Occurrence of a Composite Triple Endpoint Consisting of Death, Limb Amputation/Gangrene, and New Thrombosis | NA days |
Secondary
Proportion of Subjects With HIT With Thrombosis (HIT-T) and Isolated HIT
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.
Time frame: From the date 5 days before the positive heparin PF-4 antibody test was drawn to the date it was drawn
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| HIT-T | Proportion of Subjects With HIT With Thrombosis (HIT-T) and Isolated HIT | 71 participants |
| Isolated HIT | Proportion of Subjects With HIT With Thrombosis (HIT-T) and Isolated HIT | 284 participants |
| No HIT | Proportion of Subjects With HIT With Thrombosis (HIT-T) and Isolated HIT | 87 participants |
Secondary
Relationship of the Heparin PF-4 Antibody Titer to the Degree of Thrombocytopenia
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.
Time frame: From the time the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| HIT-T | Relationship of the Heparin PF-4 Antibody Titer to the Degree of Thrombocytopenia | 87.7 X10^9 / L | Standard Deviation 92.4 |
| Isolated HIT | Relationship of the Heparin PF-4 Antibody Titer to the Degree of Thrombocytopenia | 83.1 X10^9 / L | Standard Deviation 76.4 |
p-value: 0.58ANOVA
Secondary
Relationship of the Heparin PF-4 Antibody Titer to the Primary Endpoint
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.
Time frame: From the time the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| HIT-T | Relationship of the Heparin PF-4 Antibody Titer to the Primary Endpoint | Composite endpoint | 85 participants |
| HIT-T | Relationship of the Heparin PF-4 Antibody Titer to the Primary Endpoint | No composite endpoint | 173 participants |
| Isolated HIT | Relationship of the Heparin PF-4 Antibody Titer to the Primary Endpoint | Composite endpoint | 66 participants |
| Isolated HIT | Relationship of the Heparin PF-4 Antibody Titer to the Primary Endpoint | No composite endpoint | 117 participants |
p-value: 0.66Regression, Cox
Secondary
Relationship of the Heparin PF-4 (Platelet Factor 4) Antibody Titer to the Clinical Diagnosis
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.
Time frame: 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.
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| HIT-T | Relationship of the Heparin PF-4 (Platelet Factor 4) Antibody Titer to the Clinical Diagnosis | Optical density Results less than 1.0 | 34 participants |
| HIT-T | 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 |
| Isolated HIT | Relationship of the Heparin PF-4 (Platelet Factor 4) Antibody Titer to the Clinical Diagnosis | Optical density Results less than 1.0 | 163 participants |
| Isolated HIT | Relationship of the Heparin PF-4 (Platelet Factor 4) Antibody Titer to the Clinical Diagnosis | Optical density Results greater or equal to 1.0 | 120 participants |
| No HIT | Relationship of the Heparin PF-4 (Platelet Factor 4) Antibody Titer to the Clinical Diagnosis | Optical density Results less than 1.0 | 61 participants |
| No HIT | Relationship of the Heparin PF-4 (Platelet Factor 4) Antibody Titer to the Clinical Diagnosis | Optical density Results greater or equal to 1.0 | 26 participants |
p-value: 0.02Chi-squared
Secondary
Time to Death
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.
Time frame: From the time the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| HIT-T | Time to Death | 23.6 days | Standard Error 1.43 |
| Isolated HIT | Time to Death | 35.4 days | Standard Error 1.11 |
| No HIT | Time to Death | 34.5 days | Standard Error 2.64 |
p-value: 0.0995% CI: [0.9, 4.36]Regression, Cox
p-value: 0.4595% CI: [0.65, 2.66]Regression, Cox
Secondary
Time to Death
The median survival time is reported by each group for the time to death.
Time frame: From the time the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| HIT-T | Time to Death | 31.0 days |
| Isolated HIT | Time to Death | NA days |
| No HIT | Time to Death | NA days |
Secondary
Time to Occurrence of Limb Amputation or Limb Gangrene
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.
Time frame: From the time the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| HIT-T | Time to Occurrence of Limb Amputation or Limb Gangrene | 5 participants |
| Isolated HIT | Time to Occurrence of Limb Amputation or Limb Gangrene | 6 participants |
| No HIT | Time to Occurrence of Limb Amputation or Limb Gangrene | 1 participants |
p-value: 0.1595% CI: [0.55, 40.87]Regression, Cox
p-value: 0.7895% CI: [0.16, 11.25]Regression, Cox
Secondary
Time to Occurrence of Major Bleeding
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.
Time frame: From the time that the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| HIT-T | Time to Occurrence of Major Bleeding | 15.6 days | Standard Error 1.54 |
| Isolated HIT | Time to Occurrence of Major Bleeding | 26.5 days | Standard Error 1.36 |
| No HIT | Time to Occurrence of Major Bleeding | 17.2 days | Standard Error 0.97 |
p-value: 0.00195% CI: [1.5, 5.22]Regression, Cox
p-value: 0.0295% CI: [1.12, 3.45]Regression, Cox
Secondary
Time to Occurrence of Major Bleeding
The median survival time is reported by each group for the time to occurrence of major bleeding.
Time frame: From the time that the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| HIT-T | Time to Occurrence of Major Bleeding | 17.0 days |
| Isolated HIT | Time to Occurrence of Major Bleeding | 36.0 days |
| No HIT | Time to Occurrence of Major Bleeding | NA days |
Secondary
Time to Occurrence of Radiographically Confirmed Thromboembolism
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.
Time frame: From the time the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| HIT-T | Time to Occurrence of Radiographically Confirmed Thromboembolism | 11.1 days | Standard Error 0.48 |
| Isolated HIT | Time to Occurrence of Radiographically Confirmed Thromboembolism | 26.1 days | Standard Error 0.74 |
| No HIT | Time to Occurrence of Radiographically Confirmed Thromboembolism | 5.74 days | Standard Error 0.11 |
p-value: 0.0695% CI: [0.98, 5.79]Regression, Cox
p-value: 0.1195% CI: [0.87, 4.21]Regression, Cox
Secondary
Time to Platelet Recovery, Among Subjects With a Low Platelet Count When the Positive PF4 Antibody Test Was Drawn
Time frame: From the time that the nadir platelet count was drawn until hospital discharge, death, or day 45, whichever occurred first
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| HIT-T | 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 |
| 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 0.38 |
| No HIT | Time to Platelet Recovery, Among Subjects With a Low Platelet Count When the Positive PF4 Antibody Test Was Drawn | 2.96 days | Standard Error 0.33 |
p-value: 0.7295% CI: [0.56, 1.49]Regression, Cox
p-value: 0.3495% CI: [0.54, 1.24]Regression, Cox
Secondary
Type of Heparin Exposure - Low Molecular Weight Heparin (LMWH)
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.
Time frame: 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
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| HIT-T | Type of Heparin Exposure - Low Molecular Weight Heparin (LMWH) | Number of subjects with heparin exposure:LMWH | 15 participants |
| HIT-T | Type of Heparin Exposure - Low Molecular Weight Heparin (LMWH) | Number of subjects without heparin exposure:LMWH | 56 participants |
| Isolated HIT | Type of Heparin Exposure - Low Molecular Weight Heparin (LMWH) | Number of subjects without heparin exposure:LMWH | 236 participants |
| Isolated HIT | Type of Heparin Exposure - Low Molecular Weight Heparin (LMWH) | Number of subjects with heparin exposure:LMWH | 48 participants |
| No HIT | Type of Heparin Exposure - Low Molecular Weight Heparin (LMWH) | Number of subjects without heparin exposure:LMWH | 76 participants |
| No HIT | Type of Heparin Exposure - Low Molecular Weight Heparin (LMWH) | Number of subjects with heparin exposure:LMWH | 11 participants |
p-value: 0.37Chi-squared
Secondary
Type of Heparin Exposure - Unfractionated Heparin (UFH)
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.
Time frame: 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
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| HIT-T | Type of Heparin Exposure - Unfractionated Heparin (UFH) | Number of subjects with heparin exposure:UFH | 67 participants |
| HIT-T | Type of Heparin Exposure - Unfractionated Heparin (UFH) | Number of subjects without heparin exposure:UFH | 4 participants |
| Isolated HIT | Type of Heparin Exposure - Unfractionated Heparin (UFH) | Number of subjects with heparin exposure:UFH | 263 participants |
| Isolated HIT | Type of Heparin Exposure - Unfractionated Heparin (UFH) | Number of subjects without heparin exposure:UFH | 21 participants |
| No HIT | Type of Heparin Exposure - Unfractionated Heparin (UFH) | Number of subjects with heparin exposure:UFH | 79 participants |
| No HIT | Type of Heparin Exposure - Unfractionated Heparin (UFH) | Number of subjects without heparin exposure:UFH | 8 participants |
p-value: 0.72Chi-squared
Secondary
Use of Treatment (Non-heparin Anticoagulant) Used at the Time of Discharge
Time frame: From the time that the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| HIT-T | Use of Treatment (Non-heparin Anticoagulant) Used at the Time of Discharge | Number of subjects with treatment at discharge | 57 participants |
| HIT-T | Use of Treatment (Non-heparin Anticoagulant) Used at the Time of Discharge | Number of subjects with no treatment at discharge | 14 participants |
| Isolated HIT | Use of Treatment (Non-heparin Anticoagulant) Used at the Time of Discharge | Number of subjects with treatment at discharge | 159 participants |
| Isolated HIT | Use of Treatment (Non-heparin Anticoagulant) Used at the Time of Discharge | Number of subjects with no treatment at discharge | 125 participants |
| No HIT | Use of Treatment (Non-heparin Anticoagulant) Used at the Time of Discharge | Number of subjects with treatment at discharge | 39 participants |
| No HIT | Use of Treatment (Non-heparin Anticoagulant) Used at the Time of Discharge | Number of subjects with no treatment at discharge | 48 participants |
p-value: <0.01Chi-squared
Secondary
Use of Treatment (Non-heparin Anticoagulant) Used in Hospital
Types of treatment (direct thrombin inhibitor, fondaparinux, warfarin, no treatment) provided to subjects in hospital
Time frame: From the time that the positive heparin PF-4 antibody test was drawn until hospital discharge, death, or day 45, whichever occurred first
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| HIT-T | Use of Treatment (Non-heparin Anticoagulant) Used in Hospital | Number of subjects without treatment in hospital | 13 participants |
| HIT-T | Use of Treatment (Non-heparin Anticoagulant) Used in Hospital | Number of subjects with treatment in hospital | 58 participants |
| Isolated HIT | Use of Treatment (Non-heparin Anticoagulant) Used in Hospital | Number of subjects without treatment in hospital | 117 participants |
| Isolated HIT | Use of Treatment (Non-heparin Anticoagulant) Used in Hospital | Number of subjects with treatment in hospital | 167 participants |
| No HIT | Use of Treatment (Non-heparin Anticoagulant) Used in Hospital | Number of subjects without treatment in hospital | 44 participants |
| No HIT | Use of Treatment (Non-heparin Anticoagulant) Used in Hospital | Number of subjects with treatment in hospital | 43 participants |
p-value: <0.01Chi-squared