Impact of age on the efficacy and safety of extended-duration thromboprophylaxis in medical patients

Rivaroxaban for extended thromboprophylaxis in acutely ill medical patients 75 years of age or older

BACKGROUND

Although older patients are at increased risk for venous thromboembolism (VTE), thromboprophylaxis is underused because of bleeding concerns. The MARINER trial evaluated whether rivaroxaban reduced symptomatic postdischarge VTE in acutely ill medical patients.

OBJECTIVES

We hypothesized that rivaroxaban would have a favorable benefit/risk profile in patients ≥75 years of age.

METHODS

Patients were randomized in a double-blind manner at hospital discharge to rivaroxaban (10 mg/day for creatinine clearance ≥50 ml/min; 7.5 mg/day for ≥30-<50 ml/min) or placebo for 45 days. Using a Cox proportional hazard model including treatment as a covariate, we compared the risk of the primary efficacy outcome (symptomatic VTE plus VTE-related death in the intention-to-treat population) and safety outcome (International Society on Thrombosis and Haemostasis major bleeding in the safety population) in the prespecified subgroups of patients ≥ and <75 years of age.

RESULTS

The primary event rate in patients ≥75 years of age was 2-fold higher than that in those <75 years. The incidence of the primary efficacy outcomes in both age groups was numerically lower with rivaroxaban than with placebo (≥75: 1.2% and 1.6%, HR 0.73, 95% CI 0.43-1.22; <75 0.6% and 0.8%, HR 0.78, 95% CI 0.46-1.32; interaction p-value for age group = .85). The incidence of major bleeding was low and similar in the two age and treatment groups (interaction p value for age group = .35).

CONCLUSION

Symptomatic VTE and VTE-related death occur frequently in older patients with acute medical illness. The benefit/risk profile of rivaroxaban in patients ≥75 years of age appears consistent with that observed in the general population.

Relevance of immobility as a risk factor for symptomatic proximal and isolated distal deep vein thrombosis in acutely ill medical inpatients

Immobility is a well-recognized risk factor for deep vein thrombosis (DVT) in surgical patients, whereas the level of DVT risk conferred by immobility is less defined in patients on medical wards. The aim of this study was to establish whether immobility and its duration are associated with the risk of DVT in acutely ill medical inpatients. We conducted a cohort study in acutely ill medical inpatients. Patients underwent whole leg ultrasound for suspected lower extremity DVT and were divided into two groups according to presence or absence of immobility, defined as total bed rest or sedentary without bathroom privileges. The endpoint was the detection of proximal DVT or isolated distal DVT (IDDVT). Among the 252 acutely ill medical inpatients with immobility (age 82.6 ± 10.3 years, female 63.9%), ultrasound showed 36 (14.3%) proximal DVTs and 39 (15.5%) IDDVTs, while there were 11 (4.4%) proximal DVTs and 26 (10.5%) IDDVTs among the 248 inpatients without immobility (age 73.6 ± 14.2 years, female 54.8%). The risk of proximal DVT was higher in immobile than in mobile patients (OR 3.59, 95% CI: 1.78-7.23, p = 0.0001), whereas the risk of IDDVT was similar between the two groups (OR 1.56, 95% CI: 0.92-2.66, p = 0.111). During the first 3 days of hospitalization, the frequency of all DVTs was similar in patients with and without immobility, but it was 0.26 ± 0.03 vs 0.18 ± 0.03, respectively, after 4 days. In conclusion, immobility for more than 3 days is a risk factor for proximal DVT in acutely ill medical inpatients.

Evaluation of unmet clinical needs in prophylaxis and treatment of venous thromboembolism in at-risk patient groups: pregnancy, elderly and obese patients

BACKGROUND

Venous thromboembolism (VTE) accounts for an estimated 900,000 cases per year in the US alone and constitutes a considerable burden on healthcare systems across the globe.

OBJECTIVE

To understand why the burden is so high, qualitative and quantitative research was carried out to gain insights from experts, guidelines and published studies on the unmet clinical needs and therapeutic strategies in VTE prevention and treatment in three populations identified as being at increased risk of VTE and in whom VTE prevention and treatment were regarded as suboptimal: pregnant women, the elderly and obese patients.

METHODOLOGY

A gap analysis methodology was created to highlight unmet needs in VTE management and to discover the patient populations considered most at risk. A questionnaire was devised to guide qualitative interviews with 44 thrombosis and haemostasis experts, and a review of the literature on VTE in the specific patient groups from 2015 to 2017 was completed. This was followed by a Think Tank meeting where the results from the research were discussed.

RESULTS

This review highlights the insights gained and examines in detail the unmet needs with regard to VTE risk-assessment tools, biomarkers, patient stratification methods, and anticoagulant and dosing regimens in pregnant women, the elderly and obese patients.

CONCLUSIONS

Specifically, in pregnant women at high risk of VTE, low-molecular-weight heparin (LMWH) is the therapy of choice, but it remains unclear how to use anticoagulants when VTE risk is intermediate. In elderly patients, evaluation of the benefit of VTE prophylaxis against the bleeding risk is particularly important, and a head-to-head comparison of efficacy and safety of LMWH versus direct oral anticoagulants is needed. Finally, in obese patients, lack of guidance on anticoagulant dose adjustment to body weight has emerged as a major obstacle in effective prophylaxis and treatment of VTE.

Net-clinical benefit of extended prophylaxis of venous thromboembolism with betrixaban in medically ill patients aged 80 or more

BACKGROUND

Extended-duration thromboprophylaxis with betrixaban reduces the risk of venous thromboembolism (VTE) without increasing major bleeding rates in acutely ill medical patients as compared to standard duration enoxaparin. We aimed to assess the risk-benefit of betrixaban in patients aged ≥ 80 years enrolled in the APEX trial.

METHODS

APEX was a randomized, double-blind trial in which patients hospitalized for acute medical illnesses received enoxaparin 40 mg qd for 10 ± 4 days or oral betrixaban 80 mg qd for 35 to 42 days. The primary efficacy outcome was VTE, the principal safety outcome was major bleeding. Net clinical benefit (NCB) was defined by the occurrence of VTE or major bleeding.

RESULTS

Of 7513 patients enrolled in the APEX trial, 2781 (37%) were aged ≥ 80 years. In this subgroup, VTE or major bleeding occurred in 7.0% of betrixaban patients and in 8.4% of enoxaparin patients, for a relative risk in the NCB of 0.82 (95% confidence interval 0.62-1.10). The relative risk reduction obtained with betrixaban was similar between those aged ≥ 80 years and patients younger than 80 years (5.0% and 6.7%, respectively, NCB 0.75, 0.58-0.96, P = .024), with no significant interaction across age groups (P = .33).

CONCLUSIONS

Event rates were higher in medically ill patients aged ≥ 80 years enrolled in the APEX study than in patients younger than 80 years. The predefined NCB was reduced with extended betrixaban therapy in both groups with no signs of age-related interactions. However, the primary efficacy endpoint was not achieved with betrixaban for patients 80 years of age or older.

Has time come for the use of direct oral anticoagulants in the extended prophylaxis of venous thromboembolism in acutely ill medical patients? Yes

Betrixaban is a direct factor Xa inhibitor with a renal excretion of only approximately 5-7%. On June 23rd 2017, it became the first direct oral anticoagulant to receive Food and Drug Administration approval for the prevention of venous thromboembolism in acutely ill medical patients, and the first anticoagulant agent to be approved for extended-duration thromboprophylaxis after hospital discharge in this setting. Approval followed the results of the APEX trial, a phase III clinical trial comparing betrixaban (80 mg) administered for 35-42 days with enoxaparin (40 mg) administered for 10 ± 4 days. This study for the first time applied a risk assessment model, integrating clinical factors and a laboratory marker to identify high risk patients. To improve safety, a dose reduction was used for patients with creatinine clearance between 15 and 30 mL/min (betrixaban 40 mg and enoxaparin 20 mg) and for patients receiving concomitant treatment with potent P-glycoprotein inhibitors (betrixaban 40 mg). The primary prespecified analysis tested the hypothesis that the benefit of extended thromboprophylaxis with betrixaban was greatest in patients with elevated D-dimer, but the 21% relative risk reduction failed to meet the prespecified threshold for statistical significance. However, the analysis of the overall study population showed a favorable net clinical benefit with betrixaban, with a statistically significant reduction in all efficacy outcomes and no increase in major bleeding rates. An ongoing trial, MARINER, is also assessing a combined approach for risk stratification comparing extended-duration rivaroxaban with standard duration low molecular weight heparin.

Association between hospitalization for acute medical illness and VTE risk: A lower efficacy of thromboprophylaxis in elderly patients? Results from the EDITH case-control study

INTRODUCTION

Whether the association between hospitalization and venous thromboembolism (VTE) is modified by the use of thromboprophylaxis in older patients remains insufficiently evaluated. Our objective was to estimate VTE risk associated with hospitalization for acute medical illness depending on prescription of pharmacological thromboprophylaxis, in two different age categories using a 75years cutoff.

METHODS

Using a case-control design, we estimated the risk for symptomatic VTE associated with hospitalization for acute medical illness depending on prescription of pharmacological thromboprophylaxis in two different age categories using a 75 years cut-off.

RESULTS

750 symptomatic VTE cases and their 750 age and sex-matched controls were analyzed. A total of 145 cases (19.3%) and 91 controls (12.1%) were hospitalized for acute medical illness in the preceding 3months prior to inclusion in the study (p<0.001). Hospitalization for acute medical illness was associated with a 75% increase in VTE risk: OR 1.75 (95% CI: 1.32-2.33). In patients <75years, there was a 2-fold increase in VTE risk associated with hospitalization when thromboprophylaxis was not prescribed: OR 2.01 (95% CI: 1.11-3.62), whereas no association was found when thromboprophylaxis was prescribed: OR 0.93 (95% CI: 0.44-1.95). In patients ≥75years, VTE risk associated with hospitalization remained significant whether or not thromboprophylaxis was prescribed: OR 2.69 (95% CI 1.28-5.66) and OR 2.02 (95% CI: 1.01-4.03) respectively.

CONCLUSION

Our results suggest that VTE prevention in acutely ill medical patients may be less effective in patients ≥75years. This finding needs to be addressed in further studies.

Inappropriate prescription of low molecular weight heparins for thromboprophylaxis among older hospitalized patients

AIM

To investigate the prevalence and clinical correlates of overprescribing and underprescribing of low molecular weight heparins (LMWHs) for thromboprophylaxis among older medical inpatients.

METHODS

Eight hundred seventy six patients (mean age 81.5 ± 7.6 years, female gender 57.2 %) enrolled in a multicenter observational study of seven acute care wards of geriatric medicine in Italy. The risk of venous thromboembolism was ascertained by calculating the Padua score for each patient. Patients receiving appropriate prescription of LMHW during stay were compared to those receiving LMHW with a Padua score <4 (overprescribing group). Similarly, patients with a high thromboembolic risk (Padua score ≥4) but not receiving LMHW (underprescribing group) were compared to patients appropriately not receiving LMHW during stay. Independent correlates of overprescribing and underprescribing were investigated by logistic regression analysis.

RESULTS

Overall, 42.8 % of patients had a Padua score ≥4. LMWHs were overprescribed in 7.3 % and underprescribed in 25.2 % of patients. The number of lost basic activities of daily living (BADL) (OR = 0.25; 95 % CI 0.15-0.41) and the number of diagnoses (OR = 0.76; 95 % CI 0.61-0.95) were inversely associated with LMWH overprescription. Conversely, older age (75-84 years: OR = 2.39; 95 % CI 1.10-5.19-85 years or more: OR = 3.25, 95 % CI 1.40-7.61), anemia (OR = 1.80, 95 % CI 1.05-3.16), pressure sores (OR = 4.15, 95 % CI 1.20-14.3), number of lost BADL at the admission (OR = 3.92, 95 % CI 2.86-5.37) and number of diagnoses (OR = 1.29, 95 % CI 1.15-1.44) qualified as significant correlates of LMWH underprescription.

DISCUSSION

Underprescription and, to a lesser extent, overprescription still represent an issue among older medical inpatients.

CONCLUSION

Implementing risk-stratifying scores into clinical practice may improve appropriateness of LMWHs prescribing during hospitalization.

Variation in Definitions of Immobility in Pharmacological Thromboprophylaxis Clinical Trials in Medical Inpatients: A Systematic Review

BACKGROUND

Although immobility is a common risk factor for venous thromboembolism (VTE) in medical inpatients, lack of a consistent definition of this term may limit accurate assessment of VTE risk for thromboprophylaxis.

OBJECTIVE

To examine various definitions of immobility used in recent pharmacological thromboprophylaxis clinical trials.

DATA SOURCES

PubMed and relevant references from articles/reviews from 2008 to 2016 were searched. Randomized controlled trials (RCTs) and other clinical studies involving adult hospitalized medical patients in acute care hospital settings that used the term immobility were selected. Two investigators independently abstracted data in duplicate, and accuracy was checked by a third investigator.

RESULTS

Twenty-one clinical studies were included. There was heterogeneity among individual VTE risk factors, with respect to the definition of immobility in medical inpatients in these trials. Thirteen studies utilized objective criteria to define "immobility" including duration (12 studies) and distance or time walked (6 studies). In contrast, 7 studies focused principally on subjective definitions (ie, describing the nature of immobility rather than specifying its quantitative measurement). Three RCTs vaguely defined the level of patient's immobility after hospitalization.

CONCLUSION

Despite the well-known effectiveness of pharmacological thromboprophylaxis for the prevention of VTE in acutely ill medical patients, there is no current consensus on how to define immobility. The heterogeneous nature of definitions of immobility has led to uncertainty about the importance of immobility in VTE risk assessment models. Although clinical studies have incorporated varying definitions of immobility into their inclusion criteria, immobility as a specific VTE risk factor has not been clearly defined.

Continuation of venous thromboembolism prophylaxis after hospital discharge into the outpatient setting: the ACCEPT study

Transition from the hospital into the outpatient setting is a critical event for the appropriate provision of VTE prophylaxis. Data for this transition for the situation in Germany is scant. This was a retrospective, observational study in patients receiving in-hospital thromboprophylaxis and discharged with or without a recommendation to continue. Patient with previous thromboembolism were excluded. A total of 3,211 patients were identified by 518 physicians of which 2,853 had all data available for the present analysis; mean patient's age was 57.4 ± 17.5 (SD) years, 48.2% were male and bodyweight was 79.8 ± 16.1 kg. During hospitalization 95.5% of surgical and 84.0% of medical patients received any thromboprophylaxis, the mean hospital duration being 12.7 ± 20.3 days. Surgical patients had high, medium and low risk in 53.8, 37.1 and 9.1%, respectively. Medical patients had high, medium and low risk in 78.8, 19.8 and 1.4%. A hospital recommendation to continue thromboprophylaxis was given to 84.6% (95% CI 83.1-85.9%) of surgical and 64.9% (95% CI 59.1-70.6%) of medical patients and implemented in 96.6 and 94.3%, respectively. On the other hand, in patients without a respective hospital recommendation (15.4% of surgical and 35.1% of medical patients), thromboprophylaxis was continued in 65.3% of surgical and 73.1% of medical patients because of high risk. Our data illustrate acceptable rates of prophylaxis in surgical and medical patients in Germany. As the results show, it is essential that not only hospital physicians are aware of the actual risk at discharge, but office based physicians assess thromboembolic risk.