The incidence of heparin-induced thrombocytopenia in medical patients treated with low-molecular-weight heparin: a prospective cohort study

Blood ◽  
2005 ◽  
Vol 106 (9) ◽  
pp. 3049-3054 ◽  
Author(s):  
Paolo Prandoni ◽  
Sergio Siragusa ◽  
Bruno Girolami ◽  
Fabrizio Fabris ◽  
Keyword(s):  
Molecular Weight ◽  
Cohort Study ◽  
Prospective Cohort Study ◽  
Prospective Cohort ◽  
Low Molecular Weight Heparin ◽  
Low Molecular Weight ◽  
Medical Patients ◽  
Heparin Induced Thrombocytopenia ◽  
Medical Centers ◽  
Extensive Documentation

AbstractIn contrast with extensive documentation in patients treated with unfractionated heparin (UFH), the incidence of heparin-induced thrombocytopenia (HIT) in medical patients receiving low-molecular-weight heparin (LMWH) is less well defined. In a prospective cohort study, the platelet count was monitored in 1754 consecutive patients referred to 17 medical centers and treated with LMWH for prophylaxis or treatment of thromboembolic disorders. The diagnosis of HIT was accepted in case of a platelet drop of at least 50%, the absence of obvious explanations for thrombocytopenia, and the demonstration of heparin-dependent IgG antibodies. HIT developed in 14 patients (0.80%; 95% CI, 0.43%-1.34%), in all of them within the first 2 weeks, and was more frequent in patients who had (1.7%) than in those who had not (0.3%) been exposed to UFH or LMWH (OR = 4.9; 95% CI, 1.5-15.7). The prevalence of thromboembolic complications in HIT patients (4 of 14; 28.6%) was remarkably higher than that (41 of 1740; 2.4%) observed in the remaining patients (OR = 16.6; 95% CI, 5.0-55.0). Immune thrombocytopenia and related thromboembolism may complicate the clinical course of medical patients treated with LMWH with a frequency that is not different from that observed with the use of UFH. The previous administration of heparin increases the rate of HIT.

The use of low molecular weight heparin in pediatric patients: A prospective cohort study

2000 ◽  
Vol 136 (4) ◽  
pp. 439-445 ◽  
Author(s):  
David Dix ◽  
Maureen Andrew ◽  
Velma Marzinotto ◽  
Karen Charpentier ◽  
Suzanne Bridge ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Cohort Study ◽  
Prospective Cohort Study ◽  
Prospective Cohort ◽  
Low Molecular Weight Heparin ◽  
Pediatric Patients ◽  
Low Molecular Weight

A Meta-Analysis to Determine the Risk of Heparin Induced Thrombocytopenia (HIT) and Isolated Thrombocytopenia in Prophylaxis Studies Comparing Unfractioneted Heparin (UFH) and Low Molecular Weight Heparin (LMWH).

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2587-2587 ◽  
Author(s):  
Nadine Martel ◽  
Philip S. Wells
Keyword(s):  
Molecular Weight ◽  
Odds Ratio ◽  
Low Molecular Weight Heparin ◽  
Absolute Risk ◽  
Meta Analysis ◽  
Patient Characteristics ◽  
Low Molecular Weight ◽  
Medical Patients ◽  
Heparin Induced Thrombocytopenia ◽  
Significant Difference

Abstract HIT is an uncommon but potentially devastating complication of anticoagulation with UFH or LMWH. The absolute risk of HIT and thrombocytopenia are not clearly defined and no summary data to provide odds ratio is available. We conducted a meta-analysis to determine and compare the incidences of HIT in surgical or medical patients receiving thromboprophylaxis with either UFH or LMWH. We searched MEDLINE-OVID and MEDLINE-PubMed using and combining the following terms: heparin induced thrombocytopenia, low molecular weight heparin, prophylaxis, randomized controlled trials, prospective studies. The function Explode was used. Search was limited to humans from 1984 to 2004. Over 400 abstracts were reviewed and then 91 articles were independently reviewed by two authors, without any restriction of article language. Included studies were those comparing prophylactic UFH and LMWH and measuring HIT (defined as platelets drop > 50% or < 100 X 109/L AND positive laboratory HIT assay) or thrombocytopenia (defined as platelets drop > 50% or < 100 X 109/L) as outcomes. Studies defining thrombocytopenia with lower thresholds were excluded because cases could have been missed. Extracted data included patient characteristics, drug regimens, HIT, thrombocytopenia and venous thromboembolism rates. Disagreements were resolved by consensus. Eligible studies were included into the meta-analysis using a random-effects model to determine the odds ratio for the incidences of HIT and thrombocytopenia between UFH and LMWH. Funnel plots were made to assess possible publication bias. 17 articles were eligible with a total of 8500 patients: 2 RCTs measuring HIT; 10 RCTs measuring thrombocytopenia, and 5 prospective non-randomized studies with comparison groups measuring HIT. Three analysis were performed and all favoured the use of LMWH: 1) 2 RCTs measuring HIT showed an OR of 0.10 (95% confidence interval [CI] 0.01–0.77; p=0.03); 2) all 7 studies measuring HIT showed an OR of 0.11 (95%CI= 0.05–0.26; p< 0.00001); 3) 12 RCTs measuring thrombocytopenia showed an OR of 0.45 (95% CI= 0.26–0.80; p=0.006). Comparing the rates in the 7 studies measuring HIT UFH resulted in HIT in 3.4% (95%CI=2.6% to 4.3%) of cases and LMWH resulted in HIT in 0.2% (95% CI=0.1% to 0.6%), a statistically significant difference (p<0.0001). This meta-analysis confirms the lower incidences of HIT and thrombocytopenia with LMWH prophylaxis compared to UFH. Absolute rates of HIT with LMWH are very low. The HIT rates should be considered when determining the drug of choice for thromboprophylaxis in surgical and medical patients.

Risk for heparin-induced thrombocytopenia with unfractionated and low-molecular-weight heparin thromboprophylaxis: a meta-analysis

Blood ◽  
2005 ◽  
Vol 106 (8) ◽  
pp. 2710-2715 ◽  
Author(s):  
Nadine Martel ◽  
James Lee ◽  
Philip S. Wells
Keyword(s):  
Molecular Weight ◽  
Prospective Studies ◽  
Low Molecular Weight Heparin ◽  
Absolute Risk ◽  
Weighted Average ◽  
Controlled Trials ◽  
Low Molecular Weight ◽  
Medical Patients ◽  
Dose Frequency ◽  
Heparin Induced Thrombocytopenia

AbstractHeparin-induced thrombocytopenia (HIT) is an uncommon but potentially devastating complication of anticoagulation with unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH). Our objective was to determine and compare the incidences of HIT in surgical and medical patients receiving thromboprophylaxis with either UFH or LMWH. All relevant studies identified in the MEDLINE database (1984-2004), not limited by language, and from reference lists of key articles were evaluated. Randomized and nonrandomized controlled trials comparing prophylaxis with UFH and LMWH and measuring HIT or thrombocytopenia as outcomes were included. Two reviewers independently extracted data on thromboprophylaxis (type, dose, frequency, and duration), definition of thrombocytopenia, HIT assay, and rates of the following outcomes: HIT, thrombocytopenia, and thromboembolic events. HIT was defined as a decrease in platelets to less than 50% or to less than 100 × 109/L and positive laboratory HIT assay. Fifteen studies (7287 patients) were eligible: 2 randomized controlled trials (RCTs) measuring HIT (1014 patients), 3 prospective studies (1464 patients) with nonrandomized comparison groups in which HIT was appropriately measured in both groups, and 10 RCTs (4809 patients) measuring thrombocytopenia but not HIT. Three analyses were performed using a random effects model and favored the use of LMWH: (1) RCTs measuring HIT showed an odds ratio (OR) of 0.10 (95% confidence interval [CI], 0.01-0.2; P = .03); (2) prospective studies measuring HIT showed an OR of 0.10 (95% CI, 0.03-0.33; P < .001); (3) all 15 studies measured thrombocytopenia. The OR was 0.47 (95% CI, 0.22-1.02; P = .06). The inverse variance–weighted average that determined the absolute risk for HIT with LMWH was 0.2%, and with UFH the risk was 2.6%. Most studies were of patients after orthopedic surgery.

Inter-observer reliability of a risk assessment model for venous thromboembolism in acutely-ill medical hospitalized patients: Results from a prospective cohort study

2021 ◽  
pp. 026835552110212
Author(s):  
Cassia RL Ferreira ◽  
Marcos de Bastos ◽  
Mirella L Diniz ◽  
Renan A Mancini ◽  
Yan S Raposo ◽  
...  
Keyword(s):  
Risk Factors ◽  
Cohort Study ◽  
Venous Thromboembolism ◽  
Prospective Cohort Study ◽  
Prospective Cohort ◽  
Risk Classification ◽  
Assessment Model ◽  
Kappa Statistics ◽  
Medical Patients ◽  
Observer Reliability

Objectives To analyze the inter-observer reliability of risk for venous thromboembolism (VTE) in a population of adult acutely-ill medical patients. Methods In this prospective cohort study, we collected risk factors and risk classification for VTE using RAM IMPROVE7. Kappa statistics was used to evaluate inter-observer reliability between lead clinicians and trained researchers. We evaluated occurrence of VTE in patients with mismatched classification. Results We included 2,380 patients, median age 70 years (interquartile range [IQR], 58-79), 56.2% female. Adjusted Kappa for VTE risk factors ranged from substantial (0.64, 95% confidence interval [CI], 0.61-0.67) for “immobilization”, to almost perfect (0.98; 95% CI 0.97-0.99) for “thrombophilia”; risk classification was 0.64 (95% CI 0.60-0.67). Divergent risk classification occurred in 434 patients (18.2%) of whom seven (1.6%) developed VTE. Conclusion Despite substantial to almost perfect reliability between observers for risk factors and risk classification, lead clinicians tended to underestimate the risk for VTE.

Sign in / Sign up

Export Citation Format

Share Document