Clinical Experience With Pharmacological Venous Thromboembolism Prophylaxis in the Underweight and Critically Ill

Venous Thromboembolism Prophylaxis in Low Body Weight Critically Ill Patients

OBJECTIVE

To compare bleeding and thromboembolic events in low body weight patients receiving reduced-dose venous thromboembolism (VTE) prophylaxis versus standard-dose VTE prophylaxis.

DESIGN

Multicenter, retrospective, cohort study.

SETTING

Five Ascension Health Hospitals.

PATIENTS

Adult, critically ill, low body weight (≤50 kg) patients who received either reduced-dose VTE prophylaxis (n = 140) or standard-dose VTE prophylaxis (n = 279) for at least 48 h.

INTERVENTION

Reduced-dose prophylaxis (enoxaparin 30 mg daily or heparin 5000 units every 12 h subcutaneously) or standard-dose prophylaxis (enoxaparin 40 mg daily, enoxaparin 30 mg every 12 h, or heparin 5000 units every 8 h subcutaneously).

MEASUREMENTS AND MAIN RESULTS

A total of 419 patients were included with a mean weight of 45.1 ± 4.2 kg in the standard-dose group and 44.0 ± 5.1 kg in the reduced-dose prophylaxis group (P = .02). The primary endpoint, composite bleeding, was significantly lower in patients receiving reduced-dose prophylaxis (5% vs 12.5%, P = .02). After adjusting for confounding factors, results remained consistent demonstrating reduced composite bleeding with reduced-dose prophylaxis (odds ratio: 0.36, 95% confidence interval: 0.14-0.96). Major bleeding events occurred in 3.6% of reduced-dose patients compared with 8.6% in standard-dose patients (P = .056). Clinically relevant nonmajor bleeding (5.4% vs 2.9%, P = .24) and VTE (2.2% vs 0%, P = .08) events were similar between groups.

CONCLUSIONS

A reduced-dose VTE prophylaxis strategy in low body weight, critically ill patients was associated with a lower risk of composite bleeding and similar rate of thromboembolism.

Evaluation of an Association Between Enoxaparin Dose per Estimated Blood Volume and Clinically Relevant Bleeding in Low-Weight Trauma Patients

BACKGROUND

The optimal dosing for enoxaparin venous thromboembolism (VTE) prophylaxis in low-weight trauma patients is unknown. Estimated blood volume (EBV) has shown promise as a dose modifier.

OBJECTIVE

To characterize the association of enoxaparin dose per EBV with the prevalence of VTE and bleeding in low-weight trauma patients.

METHODS

This was a retrospective study of trauma patients admitted over a 4-year period. Included patients were adults weighing <60 kg who received a minimum of 3 consecutive doses of enoxaparin. The primary endpoint was a comparison of enoxaparin dose per EBV in patients experiencing bleeding and VTE. Secondary endpoints included comparisons of dose per body mass index (BMI) and total body weight (TBW) and the ability of dose per EBV to predict clinical endpoints. Subgroup analyses for patients weighing <50 kg were performed for all endpoints.

RESULTS

A total of 189 patients were included. Statistical comparisons for VTE were not performed because of low prevalence. The dose of enoxaparin per EBV was not statistically different between patients who did and did not bleed in all analyses. Doses per BMI and TBW were also not statistically different between the groups. In patients weighing <50 kg, numerically higher doses per EBV, BMI, and TBW were noted in patients that bled versus those that did not. Enoxaparin dose per EBV was not a statistically significant predictor of bleeding in logistic regression models.

CONCLUSION AND RELEVANCE

No significant associations between enoxaparin dose per EBV, BMI, or TBW and bleeding were noted in the study. Future analyses of EBV and other dose modifiers should consider inclusion of patients weighing <50 kg.

Assessment of bleeding risk in low-weight patients receiving prophylactic subcutaneous unfractionated heparin

BACKGROUND

Underweight patients may be at an increased risk of bleeding while receiving venous thromboembolism (VTE) prophylaxis. Additional evidence is needed to identify patient-specific factors associated with bleeding. The objective of the study was to describe the incidence and identify risk factors associated with bleeding in low-weight (⩽ 60 kg) adult patients receiving subcutaneous unfractionated heparin (SQH) for VTE prophylaxis.

METHODS

This was a single-center, retrospective, nested case-control study of low-weight patients receiving SQH for VTE prophylaxis for ⩾ 48 hours. Cases, patients with clinically relevant bleeding while receiving SQH, and controls, patients without a bleeding event, were matched in a 1:3 ratio for age, sex, primary service (surgical or medical), and time at risk of bleeding on SQH to determine factors associated with bleeding.

RESULTS

A total of 3761 patients met the inclusion criteria, of which 38 cases of clinically relevant bleeding were identified. The bleeding incidence was 1% at hospital day 6 and 2.8% at hospital day 14. Most patients in this study (69%) received SQH 5000 units three times daily. ICU admission at SQH start was associated with bleeding, OR 2.97 (95% CI 1.21-7.29).

CONCLUSION

Bleeding in low-weight patients on prophylactic SQH was uncommon. Patients admitted to the ICU at time of SQH start may be at a higher risk of bleeding. Further studies are needed to detect additional risk factors associated with bleeding and investigate the effects of reduced dosing in this population.

The Pattern of Heparin Dosing as Venous Thromboembolism Prophylaxis in Adult Underweight Patients Admitted to Critical Care Units at a Tertiary Hospital

BACKGROUND

 Venous thromboembolism (VTE) is one of the causes of hospital-related deaths in critically ill patients. Guidelines recommended VTE prophylaxis with standardized, fixed doses for most patients. The underweight population has limited data to guide the appropriate drug and dosing regimen.

OBJECTIVE

 The aim of this study was to describe the pattern of VTE prophylaxis dose regimens for underweighted critically ill adult patients and the prevalence of associated VTE and bleeding.

METHODS

 This study is a retrospective cohort study, conducted at the King Abdulaziz Medical City, Riyadh, Saudi Arabia. It included all critical patients admitted to the intensive care units (ICUs) and were above 14 years old with weight less than 50 kg or body mass index (BMI) of 18.5 kg/m² or less, and were on heparin as VTE prophylaxis for more than 72 h from January 2016 until January 2020.

RESULTS

 After screening 270 patients, only 40 patients were included in this study according to our inclusion and exclusion criteria. Only six patients (15%) received VTE prophylaxis as an adjusted dose of heparin 2500 U Q12, while the rest of the patients were taking standard dosing of heparin; 5000 U Q12 was given to 21 (52.50%) patients, and 5000 U Q8 was given to 13 (32.50%) patients. None of the adjusted doses developed any complications such as VTE or bleeding. There was no significant difference compared with the standard dose group.

CONCLUSIONS

 In this study, we described the pattern of heparin doses as VTE prophylaxis in underweight patients. We also compared the standard dosing and adjusted dosage of VTE prophylaxis on underweight patients and any complications. There was no significant difference in the complications outcome or benefits between the two groups.

Venous Thromboembolism Prophylaxis in Underweight Hospitalized Patients

There is limited evidence about optimal anticoagulant dosing for venous thromboembolism (VTE) prophylaxis in underweight patients. The purpose of this study was to characterize dosing strategies used in underweight patients and compare the incidence of bleeding and VTE to patients receiving a standard dose. This multi-center retrospective study evaluated medicine patients who weighed 45 kilograms or less and received VTE prophylaxis with unfractionated heparin or enoxaparin. We categorized subjects into groups as either standard or reduced dose and compared the incidence of bleeding and VTE between groups. Of the 300 patients included in the outcome analysis, 40.7% received a reduced dose regimen, most often enoxaparin 30 mg daily. Standard dose was associated with major bleeding compared with reduced dose, when adjusted for age, gender and admission hemoglobin (odds ratio 4.73, 95% confidence interval 1.05 to 21.34). Incidence of clinically relevant non-major bleeding (2.4% vs. 1.1%) and VTE (0.6% vs. 0%) were similar between groups. Anticoagulant dose reduction for VTE prophylaxis in underweight hospitalized medicine patients is common practice and associated with less major bleeding.

Prophylactic unfractionated heparin and hemorrhage in neurocritically ill underweight patients: A case series and review of the literature

PURPOSE

Three cases of major bleeding associated with thromboprophylactic unfractionated heparin (UFH) therapy in underweight neurocritically ill patients are reported.

SUMMARY

Three underweight patients (body mass index of <18.5 kg/m2) were treated in the intensive care unit with major bleeds associated with UFH thromboprophylaxis. Two of the patients, a 76-year-old female and a 56-year-old female, had hemorrhages on presentation; the third patient, a 29-year-old male, developed bleeding during his admission. All 3 patients had past medical histories consisting of acute neurologic conditions within 6 weeks of presentation, including subdural hematoma, subarachnoid hemorrhage, and obstructive hydrocephalus secondary to a brain mass. All hemorrhages developed following the receipt of prophylactic UFH at doses of 5,000 units every 8 to 12 hours, which translated to high weight-based dosages (>300 units/kg/d). Additionally, hemorrhages were associated with prolonged activated partial thromboplastin time, which declined following heparin discontinuation. The major bleeds following UFH administration included an acute on chronic subdural hematoma, acute rectus sheath hematoma, and cerebellar hematoma. Stabilization of the subdural hematoma was achieved without the use of protamine and the patient was discharged in stable condition. The other 2 patients expired secondary to their hemorrhagic events. Naranjo nomogram scores for the patients indicated that heparin was the probable cause of bleed in 2 cases and a possible cause in 1 case.

CONCLUSION

Three major hemorrhages developed following the administration of UFH. Underweight patients with neurologic injury may require increased clinical vigilance, reduced doses, and pharmacodynamic monitoring to improve safety outcomes associated with thromboprophylaxis.

Enoxaparin Dosing for Venous Thromboembolism Prophylaxis in Low Body Weight Patients

Background:

The appropriate dose of enoxaparin for venous thromboembolism (VTE) prophylaxis in low body weight patients is unknown.

Objective:

The aim of this study is to evaluate the impact of enoxaparin dosing on major and minor bleeding events in low body weight patients.

Methods:

This was a retrospective cohort study of patients weighing less than 45 kg receiving subcutaneous (SC) enoxaparin for VTE prevention. The primary objective was to determine whether enoxaparin dose was associated with major and minor bleeding. The secondary objective was to determine the incidence of VTE by enoxaparin dose.

Results:

There were 173 patients included in the study, of which 37 patients received 2 different courses of enoxaparin during hospitalization, resulting in 210 enoxaparin courses. Among all enoxaparin courses, 16.2% were associated with major bleeding and 5.2% with minor bleeding. There was no difference in the incidence of major bleeding by dose (enoxaparin 30 mg SC daily, 30 mg SC twice daily, or 40 mg SC daily; P = .409). Patients who experienced major bleeding were older (54.9 ± 16.1 years) than patients who did not (48.4 ± 18.4 years) (P = .043). There was no difference in the incidence of minor bleeding by dosing schedule (P = .14). No patients experienced a VTE.

Conclusion and Relevance:

The risk of bleeding was similar by enoxaparin dose but increased with age in low body weight patients. Given the low incidence of VTE in this study, it is reasonable to consider decreasing the prophylactic enoxaparin dose in low body weight patients, especially in the elderly population.

Practice Patterns of Venous Thromboembolism Prophylaxis in Underweight, Critically Ill Patients with Neurologic Injury

PURPOSE

Venous thromboembolism (VTE) prophylaxis in underweight patients with neurologic injury remains unaddressed by guidelines and primary literature. This study aimed to describe VTE prophylaxis strategies employed in this population and compare the impact of underweight and non-obese patients on thrombotic and bleeding events.

METHODS

A retrospective review of adults admitted with a diagnosis of neurologic injury to a neurology/neurosurgery intensive care unit (ICU) over 6 years. Patients admitted ≥72 h with an order for VTE prophylaxis during admission, and a body mass index (BMI) <30 kg/m² were included. Patients were stratified to underweight (BMI ≤18.5 kg/m² or weight ≤50.0 kg) or non-obese (BMI 18.6-29.9 kg/m²) groups and matched, 2:1, on age, diagnosis, and disease severity.

RESULTS

The most common regimen in the underweight (n = 107) and non-obese (n = 214) group was unfractionated heparin (UFH) 5000 units subcutaneously Q12 h (69.1 vs. 83.6%; p = 0.003). Only underweight patients received UFH 2500 units subcutaneously Q12 h (17.8 vs. 0.0%; p < 0.0001). The proportion of overall bleeding and thrombotic events while receiving VTE prophylaxis was not significantly different. The proportion of underweight patients developing intracranial hematoma expansion while receiving prophylaxis versus non-obese patients (45.5 vs. 8.3%; p = 0.017) was significant. Patients receiving >150 units/kg/day of UFH displayed a trend toward increased risk of bleeding (9.7 vs. 4.2%; p = 0.064).

CONCLUSIONS

Current practice does not reflect dose reductions for neurologically injured, underweight patients. Caution should be considered when using increased doses of UFH in neurologically injured patients that are underweight and/or may be exposed to >150 units/kg/day of UFH. Continued assessment of VTE prophylaxis is needed to confirm these findings.