Haemorrhagic Complications of Vitamin K Antagonists in the Elderly

The impact of advanced age on anticoagulant therapy for acute venous thromboembolism

INTRODUCTION

Management of venous thromboembolic events (VTE) has been completely changed after the introduction of direct oral anticoagulants (DOAC). VTE is common in the geriatric population, but the management of DOACs remains complex because of the lack of specific data in this polymedicated fragile population.An exhaustive search of anticoagulants in the indication of VTE was performed on PubMed, including data from clinical trials, observational studies, real-world data, drug-drug interaction studies, as well as various guidelines from scientific societies.

AREAS COVERED

The present review aims to summarize our current knowledge on the era of DOACs in the management of VTE in the elderly. This involves learning the pharmacokinetics/pharmacodynamics of drugs specific to geriatrics, the problem of drug-drug interactions, and the main randomized clinical trials validating the use of DOACs.

EXPERT OPINION

DOACs have become an essential part of the management of VTE in the elderly, both for their efficacy and safety. However, we are faced with a list of unmet needs, such as the relevance of DOACs in the very elderly, cancer patients, and those with renal impairment. Clinicians and pharmacists must remain cautious about comedications, as well as about the patient's comorbidities.

Efficacy and Safety of Warfarin Experience in a Stroke Polyclinic in Stroke Patients

Introduction

Cardioembolic stroke is associated with high morbidity and mortality, with an increased risk of recurrent stroke. Oral anticoagulation is highly effective in reducing the risk of stroke and mortality compared with placebo. Our study aimed to highlight the safety and efficacy of warfarin by analyzing the 20-year follow-up of patients on warfarin therapy.

Methods

A retrospective observational study was performed with ischemic stroke patients receiving warfarin at our stroke polyclinic between 1992 and 2012. The CHADS2 scoring system was used to assess the annual risk of stroke, and a bleeding risk score termed the HAS-BLED scoring system was calculated to estimate the risk of bleeding.

Results

In our study, 394 patients who were receiving warfarin therapy were included. The patients' median age was 66.35±13.602 years. The median follow-up period of the patients was 4.85±3.572 years. During follow-up, 79.9% of the patients revealed no complication on warfarin therapy. Thirty-seven patients had hemorrhagic complications; among these, 33 had systemic complications (including nose bleeding, hematuria, hematochezia) and 4 patients had intracerebral bleeding. The INR value related to hemorrhagic complications was >2.5 in 75.8% of 33 patients having systemic bleeding and in 75% of 4 patients having intracerebral bleeding. The HAS-BLED risk score was >3 in 72.7% of the patients experiencing systemic bleeding complications. Forty-one patients had a recurrent ischemic stroke/TIA during the follow-up. Of this patient group, the INR value at the time of recurrent ischemic stroke was <2 in 41 patients (92.7%), while the CHADS2 risk score was low in this group. Sixty-eight patients were receiving antiplatelet therapy with warfarin. In these groups, 16 patients experienced a complication during the follow-up (bleeding/ischemic), while 10 patients had bleeding complications (systemic and intracerebral).

Conclusion

The results suggest that the effectiveness and safety of warfarin depend on maintaining its dose at sufficient levels to keep the patient's INR within the therapeutic range.

Warfarin Dose Model for the Prediction of Stable Maintenance Dose in Indian Patients

The main aim of this study was to screen various genetic and nongenetic factors that are known to alter warfarin response and to generate a model to predict stable warfarin maintenance dose for Indian patients. The study comprised of 300 warfarin-treated patients. Followed by extensive literature review, 10 single-nucleotide polymorphisms, that is, VKORC1-1639 G>A (rs9923231), CYP2C9*2 (rs1799853), CYP2C9*3 (rs1057910), FVII R353Q (rs6046), GGCX 12970 C>G (rs11676382), CALU c.*4A>G (rs1043550), EPHX1 c.337T>C (rs1051740), GGCX: c.214+597G>A (rs12714145), GGCX: 8016G>A (rs699664), and CYP4F2 V433M (rs2108622), and 5 nongenetic factors, that is, age, gender, smoking, alcoholism, and diet, were selected to find their association with warfarin response. The univariate analysis was carried out for 15 variables (10 genetic and 5 nongenetic). Five variables, that is, VKORC1-1639 G>A, CYP2C9*2, CYP2C9*3, age, and diet, were found to be significantly associated with warfarin response in univariate analysis. These 5 variables were entered in stepwise and multiple regression analysis to generate a prediction model for stable warfarin maintenance dose. The generated model scored R² of .67, which indicates that this model can explain 67% of warfarin dose variability. The generated model will help in prescribing more accurate warfarin maintenance dosing in Indian patients and will also help in minimizing warfarin-induced adverse drug reactions and a better quality of life in these patients.

Acquired Inhibitors: A Special Case of Bleeding in Older Adults

This literature review is intended to familiarize physicians and healthcare providers of older adults with the potential causes of acute bleeding in older adults and to review diagnostic approaches that can produce prompt identification of acute bleeding and facilitate timely treatment. Adverse events from anticoagulant treatment and nonsteroidal anti-inflammatory drug (NSAID) and aspirin use and abuse are among the most common causes of bleeding in older adults. Diagnoses infrequently considered—mild congenital hemophilia, acquired hemophilia, von Willebrand disease, and platelet dysfunction—can contribute to acute bleeding in older adults. The approach to management of bleeding varies. Management of acute bleeding in older adults can be challenging because these patients often have chronic comorbidity and have been prescribed long-term concomitant medications that can complicate diagnosis and treatment. Prompt recognition of acquired hemophilia, referral to an expert hematologist, and timely initiation of treatment could improve outcome in older patients who experience bleeding episodes resulting from this condition.

Pharmacological adherence to oral anticoagulant and factors that influence the international normalized ratio stability

Cross-sectional study developed to relate the international normalized ratio (INR), used as a parameter to monitor the levels of blood clotting, stability to adherence, age, level of education, socioeconomic level, interaction with other drugs, comorbidities, vitamin K intake, anticoagulation time and drug cost. 156 patients were included, mean age 57 ± 13 years, (53.8%) male, 61 (39.1%) had high adherence, 91 (58.3%) medium and 4 (2.6%) low adherence to treatment, 117 (75%) had INR stability up to 50% and 39 (25%) > 75%, patients with shorter time of anticoagulation presented higher stability, those who spent less on the drug remained more stable and had better adherence. It was concluded that more than 90% of patients had high and medium adherence and that the anticoagulation time and drug cost were the factors related to the anticoagulation stability.

Reversal of overanticoagulation in very elderly hospitalized patients with an INR above 5.0: 24-hour INR response after vitamin K administration

BACKGROUND

Reversal of overanticoagulation to minimize the bleeding risk is important in elderly inpatients receiving vitamin K antagonist therapy. However, no study has specifically focused on this population. The objective of this study is to evaluate whether guidelines based on American College of Chest Physicians recommendations for the management of overanticoagulation (international normalized ratio [INR] ≥5.0) can apply to elderly inpatients, and notably allow 24-hour INRs to return to the 1.8-3.2 range in this population. The influence of different factors on the vitamin K response also was evaluated.

METHODS

Inpatients aged ≥75 years with INR ≥5.0 were included in this observational study. INRs were assessed on the day of the overdosage (Day 0) and on the following day (Day 1).

RESULTS

Of 385 Day 0 INRs ≥5.0 (239 patients; 86±6 years), 217 were managed according to recommendations, with a mean INR decreasing from 6.8±2.4 (range: 5.0-20.0) on Day 0 to 2.7±1.3 (range: 1.1-10.1) on Day 1 (P<.0001); 55% of INRs were within the 1.8-3.2 range, 20% <1.8, and 25% >3.2. In the subset of Day 0 INRs between 5.0 and 6.0, mean INR decreased from 5.5±0.3 to 2.7±1.0 (P<.0001) on Day 1 after oral administration of 1 mg vitamin K1 (n=121) and from 5.3±0.3 to 5.0±1.6 (P=.149) without vitamin K1 administration (n=48). Among covariates entered in the multivariate analysis, including co-medications, only the vitamin K1 dose influenced Day 1 INRs, with higher doses of vitamin K1 associated with Day 1 INRs <1.8 (P<.0001).

CONCLUSION

In elderly inpatients with INR ≥5.0, both vitamin K antagonist dose omission and vitamin K1 administration according to recommendations were effective in reversing overanticoagulation, allowing most INRs to return to the 1.8-3.2 range without excessive overcorrection. Therefore, American College of Chest Physicians recommendations may be applied to elderly inpatients.

Bleeding rates in patients older than 90 years of age on vitamin K antagonist therapy for nonvalvular atrial fibrillation

Extremely elderly patients are being treated with anticoagulant therapy with increasing frequency. We sought to assess the rates of bleeding in such patients and to carefully examine risk factors that might predict this bleeding. This was a prospective cohort study conducted from 1 January 2007 to 29 February 2008 at an anticoagulation clinic in Modena, Italy. Ninety patients, 90 years or older, among 1635 patients with nonvalvular atrial fibrillation were studied; 69 (77%) were women with a median age of 91.71 years (range 90-98). During the enrolment period, all the patients were interviewed during an ambulatory visit and were followed in the outpatient setting. Hemorrhagic, thromboembolic and fatal events over 1 year of follow-up were monitored. Six (7%) patients discontinued vitamin K antagonists (three due to bleeding, two due to noncompliance, two due to physician recommendation). Twenty-one (23%) patients died, and 35 (39%) were admitted to hospital. One patient had an intracranial hemorrhage [1%, 95% confidence interval (CI) 0.27-6.0], two patients had a major extracranial hemorrhage (2%, 95% CI 0.7-8.0). One patient had an ischemic stroke (1%, 95% CI 0.27-6.0), two patients had embolic arterial ischemia (2%, 95% CI 0.7-8.0). All the events occurred when the international normalized ratio was outside the target range, or after oral anticoagulation had been stopped. In our study of extremely elderly anticoagulated patients, we found low rates of bleeding and thromboembolism. These findings support the use of oral anticoagulants in such patients.

Warfarin potentiation: a review of the "FAB-4" significant drug interactions

Warfarin is an anticoagulant with numerous drug-drug interactions. Four significant drug interactions with warfarin are: fluconazole, amiodarone, sulfamethoxazole/trimethoprim, and metronidazole. Potentially life-threatening interactions with these medications are a common occurrence because they have a broad spectrum of indications in elderly individuals. With the increasing number of elderly individuals, who consume a disproportionate number of medications, cautious monitoring for these drug interactions is essential. Drug interactions often are overlooked despite computer alert systems. Careful analysis of each patient's situation will help in evaluating whether the use of a medication is appropriate. Through knowledge of potential mechanisms of interaction, management options such as dose reductions and/or the use of alternative agents should be used in determining the appropriate drug therapy.

Management and outcome of patients with acute traumatic subdural hematomas and pre-injury oral anticoagulation therapy

BACKGROUND

Acute subdural hematomas (aSDHs) are found in up to one-third of patients with severe traumatic brain injury and are associated with an unfavorable outcome in the majority of cases. Mortality ranges between 40 and 60%, but was reported to be even higher in patients undergoing oral anticoagulation therapy (OAT) at the time of injury. The objective of this study is to specifically report on the peri-operative management and outcome of patients with aSDH and pre-injury OAT.

MATERIAL AND METHODS

From June 2002 to June 2006, all patients with OAT who underwent surgical treatment of aSDH were retrospectively analysed. Results of pre-operative blood tests, the peri-operative and surgical management and the clinical courses were assessed. Patient outcome is reported according to the Glasgow Outcome Scale (GOS) at 6 months.

RESULTS

Eleven (10.3%) out of 107 patients with aSDH were on OAT. Patients with OAT were significantly older than patients without OAT (72.4 +/- 9.3 versus 59.9 +/- 17.5 years; p<0.05, Mann-Whitney U-test). Intensity of head trauma was moderate in four and severe in seven patients with a median pre-operative Glasgow Coma Scale (GCS) of 8. Median pre-treatment prothrombin time and international normalized ratio were 23% (range: 10-65%) and 3.3 (range: 1.5-10.6), respectively. Replacement therapy consisted of administration of prothrombin complex concentrates, vitamin K and FFP (fresh frozen plasma). In four patients, antithrombin was additionally given to prevent disseminated intravascular coagulation. Surgical treatment consisted of craniotomy (n=10) or craniectomy (n=1) and hematoma evacuation with intracranial pressure probe placement. Low molecular weight heparin was administered as pharmacological prophylaxis of thrombembolic events in an increasing dose post-operatively. At 6 months, six out of 11 patients survived with a median GOS of 4. All-cause mortality was 45.5%. A pre-operative GCS of < or = 8 was not associated with an increased risk of mortality (p>0.5, Fisher's exact test). No relevant rebleedings or thrombembolic complications were observed. The mortality rate of patients who did not undergo OAT was 50%.

CONCLUSION

A large number of patients with aSDH are on pre-injury OAT. Specific replacement therapy facilitates successful clot evacuation without bleeding complications. The overall outcome of these patients does not seem to differ from historical cohorts with aSDH without OAT, but a large prospective multicenter study is warranted to answer that question.

Emergency correction of coagulation before major surgery in two elderly patients on oral anticoagulation

Recommendations for urgent reversal of oral anticoagulation with vitamin K1 antagonists are largely derived from case series employing empirical dosing regimens with vitamin K1 and prothrombin complex concentrates. Data on the use of prothrombin complex concentrates in this indication are scarce in the elderly who are at high risk of both hemorrhagic and thrombotic complications. The two cases presented here describe patients older than 75 years who underwent rapid International Normalized Ratio (INR) reversal with prothrombin complex concentrates for surgical treatment of a bleeding ruptured spleen and for emergency surgery of a dissecting aorta. Both patients had their INRs rapidly corrected to <or= 1.6 and underwent operation without complications. Evidence on treatment of patients who present with elevated INR and who have major bleeding or need to undergo emergency surgery is based mainly on observational studies. The two elderly patients presented here underwent successful emergency surgery after their INRs had been corrected with the intravenous use of vitamin K1 in combination with prothrombin complex concentrate that was administered according to current guideline recommendations.