Biomedical subjects

Marc Carrier

Publications and source records attributed to Marc Carrier.

5 recordsLinked to original sources

PubMed2006

The prevalence of antibodies to the platelet factor 4 -heparin complex and association with access thrombosis in patients on chronic hemodialysis.

INTRODUCTION: Heparin-induced thrombocytopenia is a serious complication that can lead to thrombocytopenia, venous and arterial thrombosis. Patients with this disorder develop antibodies to the platelet factor 4-heparin (PF4-H) complex. Hemodialysis patients are repeatedly exposed to heparin and are at risk for developing PF4-H antibodies. We sought to determine the prevalence of PF4-H antibodies in a large cohort of patients on chronic hemodialysis and to evaluate the relationship between PF4-H antibodies and hemodialysis vascular access thrombosis in a case-control study. MATERIAL AND METHODS: Pre-dialysis blood samples were drawn on 419 patients; 107 cases with access thrombosis and 312 controls that never had access thrombosis. All samples were screened for PF4-H antibodies using an ELISA assay (GTI PF4 Enhanced, GTI Diagnostics). All positive and indeterminate samples were then tested using an IgG-specific PF4-H ELISA assay and a platelet serotonin-release assay. RESULTS: Antibodies to PF4-H were positive in 54 (12.9%) patients using the screening ELISA assay. Nine (2.1%) patients had IgG-specific PF4-H antibodies. None of the patient's had a positive platelet serotonin-release assay. No relationship between hemodialysis access thrombosis and PF4-H antibodies was noted using the screening ELISA assay (unadjusted odds ratio 0.63; 95% CI 0.30-1.30; P = 0.21), the IgG-specific ELISA assay (unadjusted odds ratio 0.83; 95% CI 0.17-4.06; P = 0.82) or indeterminate platelet serotonin-release assay results (unadjusted odds ratio 0.97;95% CI 0.10-9.44;P = 0.98). CONCLUSIONS: Hemodialysis with repeated exposure to unfractionated heparin was associated with a moderately elevated prevalence of PF4-H antibodies. However, our results do not support a relationship between PF4-H antibodies and hemodialysis vascular access thrombosis.

Adult↗

PubMed2006

Excluding pulmonary embolism at the bedside with low pre-test probability and D-dimer: safety and clinical utility of 4 methods to assign pre-test probability.

INTRODUCTION: Less than 35% of patients suspected of having pulmonary embolism (PE) actually have PE. Safe bedside methods to exclude PE could save scarce health care resources if they exclude large proportions of patients with suspected PE and are widely applicable. Non-Elisa D-dimer in combination with pre-test probability of suspected PE can safely exclude PE at the bedside. Pre-test probability can be assigned by gestalt or by using clinical models (Wells, Wicki, Rodger). MATERIALS AND METHODS: We combined two databases from studies of patients with suspected PE and retrospectively compared the diagnostic test characteristics of the different methods of assigning pre-test probability. RESULTS: 535 patients were studied. PE was confirmed in 20.8% of study patients. Two clinical predictive models (Rodger and Wells) and overall diagnostic impression have similar sensitivities ranging from 96% (95% confidence interval (CI) 89-99%) to 99% (93-100%). Wicki's model has a sensitivity of 89% (77-96%). The Wells' model with a cutoff of less than 2 points in association with semi-quantitative D-dimer has a specificity of 11% (CI 7-15%). The specificities for the other clinical predictive model are ranging from 21% (17-25%) to 49% (CI 42-55%). CONCLUSION: Semi-quantitative D-dimer must be combined with safe clinical probability assessment to safely exclude PE in a significant proportion of patients. Wicki's model in association with semi-quantitative D-dimer has the lowest sensitivity and should be used carefully to exclude PE at the bedside. The Wells' model with a cutoff of less than 2 points when combined with semi-quantitative D-dimer excluded very few patients and therefore limits its clinical utility.

Aged↗

PubMed2003

The outpatient treatment of deep vein thrombosis delivers cost savings to patients and their families, compared to inpatient therapy.

BACKGROUND: The outpatient treatment of deep vein thrombosis (DVT) with low-molecular-weight heparin (LMWH) has been shown to be cost-effective from the perspective of a third party payer. The aim of this study is to determine if some or all of these cost savings to third party payers are shifted to patients and their families. METHODS: A prospective cohort study with micro-costing of patient/family costs was conducted at the thrombosis units of The Ottawa Hospital. Costs were determined by administering a questionnaire at the end of the patients' heparin therapy. Over a period of 4 months, consecutive patients presenting at the thrombosis units were approached at the initiation of their heparin therapy; 44 patients consented to participate and completed questionnaires were obtained for 41. RESULTS: The mean patient/family costs associated with outpatient therapy were significantly less than those associated with inpatient therapy (219.42 dollars versus 402.93 dollars, p=0.003); a savings of 190.91 dollars per patient. Even when lost income to patients/families was ignored, mean patient/family costs remained significantly less for outpatient therapy (72.00 dollars versus 134.29 dollars, p=0.004); a savings of 62.30 dollars per patient. Furthermore, patients preferred outpatient to inpatient therapy by almost 3:1 (30 versus 11, respectively). INTERPRETATION: The outpatient treatment of DVT does not result in any net shifting of costs to patients and their families, and further, brings about cost savings. Given the cost savings associated with and the preference of patients for outpatient care, this study further supports the shift of DVT therapy from the inpatient unit to the outpatient clinic.

Adult↗

PubMed2002

The management of thrombophilia during pregnancy: a Canadian survey.

OBJECTIVE: To determine current Canadian practice patterns in the management of pregnant women with thrombophilia. METHODS: Physician members of the Society of Obstetricians and Gynaecologists of Canada (SOGC) who provide obstetrical care were invited to complete a closed-ended questionnaire in which they were presented 5 clinical scenarios involving thrombophilic pregnancies and asked to give their management recommendations. The 5 scenarios presented in the survey were of a pregnant woman with (1) asymptomatic factor V Leiden (FVL), (2) asymptomatic FVL and a family history of venous thromboembolism (VTE), (3) FVL and recurrent fetal loss, (4) FVL and a previous VTE, or (5) antiphospholipid antibody syndrome and recurrent fetal loss. RESULTS: Of the 1448 eligible SOGC members invited, 18 had moved with no forwarding address, and 662 (46.3% of the remainder) responded. The majority (65%) of the respondents were obstetricians and 51% of them had a university-affiliated practice. In scenario 1, 26% of physicians indicated they would recommend some form of antepartum thromboprophylaxis, whereas in the remaining four scenarios, 58% to 84% would definitely recommend antepartum thromboprophylaxis. CONCLUSION: Most clinicians favour intervening with thromboprophylaxis in pregnant thrombophilic women rather than observing without prophylaxis. This tendency spans a wide range of clinical scenarios, despite a lack of evidence to support such decisions. This survey highlights the need to provide clinicians and women with evidence for the safety and effectiveness of prophylaxis, before these interventions become the default recommendation by clinicians caring for this prevalent group of women.

Abortion, Habitual↗

PubMedDate not supplied

Normal functional protein S activity does not exclude protein S deficiency.

Protein S (PS) deficiency appears to increase the risk of venous thrombosis. PS deficiency is classified into three phenotypes using antigenic levels and functional activity. By definition, all three phenotypes of PS deficiency should result in low activated protein C cofactor activity. We compared the results of functional PS activity testing to free antigenic PS testing in order to determine if a normal functional PS activity assay result could eliminate the need for free antigenic PS testing. The sensitivity of the functional assay is 45.5% (95% confidence interval, CI, 36-55%), specificity 95.3% (95% CI 93-97%), negative predictive value 88.6% (95% CI 86-91%) with a positive predictive value of 68.5% (95% CI 57-79%). In conclusion, a normal functional PS activity result does not exclude free antigenic PS deficiency. Functional PS activity testing should not be used as a screening test to eliminate free antigenic PS testing for the laboratory diagnosis of PS deficiency.

Activated Protein C Resistance↗