Management and prognosis of life-threatening bleeding during warfarin therapy. National Consortium of Anticoagulation Clinics

Prescribed Drug Use and Aneurysmal Subarachnoid Hemorrhage Incidence: A Drug-Wide Association Study

BACKGROUND AND OBJECTIVES

Current benefits of invasive intracranial aneurysm treatment to prevent aneurysmal subarachnoid hemorrhage (aSAH) rarely outweigh treatment risks. Most intracranial aneurysms thus remain untreated. Commonly prescribed drugs reducing aSAH incidence may provide leads for drug repurposing. We performed a drug-wide association study (DWAS) to systematically investigate the association between commonly prescribed drugs and aSAH incidence.

METHODS

We defined all aSAH cases between 2000 and 2020 using International Classification of Diseases codes from the Secure Anonymised Information Linkage databank. Each case was matched with 9 controls based on age, sex, and year of database entry. We investigated commonly prescribed drugs (>2% in study population) and defined 3 exposure windows relative to the most recent prescription before index date (i.e., occurrence of aSAH): current (within 3 months), recent (3-12 months), and past (>12 months). A logistic regression model was fitted to compare drug use across these exposure windows vs never use, controlling for age, sex, known aSAH risk factors, and health care utilization. The family-wise error rate was kept at p < 0.05 through Bonferroni correction.

RESULTS

We investigated exposure to 205 commonly prescribed drugs between 4,879 aSAH cases (mean age 61.4, 61.2% women) and 43,911 matched controls. We found similar trends for lisinopril and amlodipine, with a decreased aSAH risk for current use (lisinopril odds ratio [OR] 0.63, 95% CI 0.44-0.90, amlodipine OR 0.82, 95% CI 0.65-1.04) and an increased aSAH risk for recent use (lisinopril OR 1.30, 95% CI 0.61-2.78, amlodipine OR 1.61, 95% CI 1.04-2.48). A decreased aSAH risk in current use was also found for simvastatin (OR 0.78, 95% CI 0.64-0.96), metformin (OR 0.58, 95% CI 0.43-0.78), and tamsulosin (OR 0.55, 95% CI 0.32-0.93). By contrast, an increased aSAH risk was found for current use of warfarin (OR 1.35, 95% CI 1.02-1.79), venlafaxine (OR 1.67, 95% CI 1.01-2.75), prochlorperazine (OR 2.15, 95% CI 1.45-3.18), and co-codamol (OR 1.31, 95% CI 1.10-1.56).

DISCUSSION

We identified several drugs associated with aSAH, of which 5 drugs (lisinopril and possibly amlodipine, simvastatin, metformin, and tamsulosin) showed a decreased aSAH risk. Future research should build on these signals to further assess the effectiveness of these drugs in reducing aSAH incidence.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that some commonly prescribed drugs are associated with subsequent development of aSAH.

Simultaneous intrahepatic and subgaleal hemorrhage in antiphospholipid syndrome following anticoagulation therapy

Warfarin is a widely used anticoagulant. Interindividual differences in drug response, a narrow therapeutic range and the risk of bleeding render warfarin difficult to use clinically. An 18-year-old woman with antiphospholipid syndrome received long-term warfarin therapy for a recurrent deep vein thrombosis. Six years later, she developed right flank pain. We diagnosed intrahepatic and subgaleal hemorrhages secondary to anticoagulation therapy. After stopping oral anticoagulation, a follow-up computed tomography showed improvement in the hemorrhage. After restarting warfarin because of a recurrent thrombosis, the intrahepatic hemorrhage recurred. We decided to start clopidogrel and hydroxychloroquine instead of warfarin. The patient has not developed further recurrent thrombotic or bleeding episodes. Intrahepatic hemorrhage is a very rare complication of warfarin, and our patient experienced intrahepatic and subgaleal hemorrhage although she did not have any risk factors for bleeding or instability of the international normalized ratio control.

Minor bleeds alert for subsequent major bleeding in patients using vitamin K antagonists

Vitamin K antagonists (VKA) are effective in primary and secondary prevention of thromboembolism, but the associated risk of bleeding is an important limitation. The majority of bleeds are clinically mild. In this study, we assessed whether these minor bleeds are associated with major bleeding, when controlling for other important risk indicators, including the achieved quality of anticoagulation. For this, 5898 patients attending a specialized anticoagulation clinic were retrospectively studied for 1 year after initiation of VKA therapy. The risk of major bleeding was estimated using a multivariate piecewise exponential model with time-varying exposure for occurring minor bleeds. In patients with a minor bleed (N=1015) subsequent major bleeding occurred more frequently than in patients without a minor bleed (N=4883), with an incidence rate of 2·3 [95% confidence interval (CI) 1·4-3·7] vs. 1·2 per 100 person-years (95% CI 0·9-1·7). The adjusted relative risk of subsequent major bleeding after a minor bleed was 2·9 (95% CI 1·1-7·2, P =0·024). The percentage of time that a patient had an International Normalized Ratio (INR) above 5 was also independently associated with major bleeding, with a 2·2-fold increased risk in patients with at least 9% of time above INR 5 (95% CI 1·3-4·0, P=0·006). Minor bleeds alert for subsequent major bleeding, independent of the quality of anticoagulation.

Factors affecting adherence to guidelines for antithrombotic therapy in elderly patients with atrial fibrillation admitted to internal medicine wards

INTRODUCTION

Current guidelines for ischemic stroke prevention in atrial fibrillation or flutter (AFF) recommend Vitamin K antagonists (VKAs) for patients at high-intermediate risk and aspirin for those at intermediate-low risk. The cost-effectiveness of these treatments was demonstrated also in elderly patients. However, there are several reports that emphasize the underuse of pharmacological prophylaxis of cardio-embolism in patients with AFF in different health care settings.

AIMS

To evaluate the adherence to current guidelines on cardio-embolic prophylaxis in elderly (> 65 years old) patients admitted with an established diagnosis of AFF to the Italian internal medicine wards participating in REPOSI registry, a project on polypathologies/polytherapies stemming from the collaboration between the Italian Society of Internal Medicine and the Mario Negri Institute of Pharmacological Research; to investigate whether or not hospitalization had an impact on guidelines adherence; to test the role of possible modifiers of VKAs prescription.

METHODS

We retrospectively analyzed registry data collected from January to December 2008 and assessed the prevalence of patients with AFF at admission and the prevalence of risk factors for cardio-embolism. After stratifying the patients according to their CHADS(2) score the percentage of appropriateness of antithrombotic therapy prescription was evaluated both at admission and at discharge. Univariable and multivariable logistic regression models were employed to verify whether or not socio-demographic (age >80years, living alone) and clinical features (previous or recent bleeding, cranio-facial trauma, cancer, dementia) modified the frequency and modalities of antithrombotic drugs prescription at admission and discharge.

RESULTS

Among the 1332 REPOSI patients, 247 were admitted with AFF. At admission, CHADS(2) score was ≥ 2 in 68.4% of patients, at discharge in 75.9%. Among patients with AFF 26.5% at admission and 32.8% at discharge were not on any antithrombotic therapy, and 43.7% at admission and 40.9% at discharge were not taking an appropriate therapy according to the CHADS(2) score. The higher the level of cardio-embolic risk the higher was the percentage of antiplatelet- but not of VKAs-treated patients. At admission or at discharge, both at univariable and at multivariable logistic regression, only an age >80 years and a diagnosis of cancer, previous or active, had a statistically significant negative effect on VKAs prescription. Moreover, only a positive history of bleeding events (past or present) was independently associated to no VKA prescription at discharge in patients who were on VKA therapy at admission. If heparin was considered as an appropriate therapy for patients with indication for VKAs, the percentage of patients admitted or discharged on appropriate therapy became respectively 43.7% and 53.4%.

CONCLUSION

Among elderly patients admitted with a diagnosis of AFF to internal medicine wards, an appropriate antithrombotic prophylaxis was taken by less than 50%, with an underuse of VKAs prescription independently of the level of cardio-embolic risk. Hospitalization did not improve the adherence to guidelines.

Use of vitamin K antagonists and risk of subarachnoid haemorrhage: a population-based case-control study

BACKGROUND

Oral anticoagulant therapy with vitamin K antagonists is associated with an increased risk of bleeding, particularly gastrointestinal bleeding. It remains unclear, however, whether use of these medications is a risk factor for subarachnoid haemorrhage (SAH). We therefore examined the association between oral vitamin K antagonist use and risk of SAH.

METHODS

We conducted this population-based case-control study using medical databases in Northern Denmark (population 1,150,000). We identified 1188 patients admitted to neurologic or neurosurgical departments with a first-time diagnosis of SAH between 1996 and 2008 and 11,880 population controls. We obtained information on use of vitamin K antagonists, other medication use, and comorbidity. We used logistic regression analysis to compute odds ratios (ORs) comparing oral anticoagulant users and non-users, controlling for potential confounding factors.

RESULTS

9 cases (0.8%) and 157 controls (1.3%) were current users of vitamin K antagonists (at least one prescription filled within 90 days of the diagnosis/index date). Current use of vitamin K antagonists was not associated with increased SAH risk compared with non-use [adjusted OR=0.80 (95% CI: 0.37-1.74)]. Changing the exposure window from 90 days to 120 days or to 60 days before the diagnosis/index date did not change the estimate substantially.

CONCLUSION

We found no evidence to support an association between use of vitamin K antagonists and increased SAH risk.

Treatment of coumarin-associated coagulopathy: a systematic review and proposed treatment algorithms

BACKGROUND

An excessive anticoagulant effect because of coumarins is frequently encountered.

OBJECTIVE

To review available literature on the management of warfarin-associated coagulopathy and to propose evidence-based treatment algorithms.

METHODS

Data sources were Medline and Embase. Papers published between 1966 and December 2005 describing randomized trials or prospective cohort studies evaluating treatments for coumarin-associated coagulopathy were abstracted.

RESULTS

Low dose oral vitamin K rapidly and reliably returns the international normalized ratio (INR) to the usual therapeutic range in non-bleeding patients. Simple withholding of acenocumarol results in rapid correction of its anticoagulant effect. The impact of oral vitamin K on phenprocumon-associated coagulopathy cannot be determined from available literature. Intravenous vitamin K and coagulation factors should be given to patients with major or life-threatening hemorrhage. The optimal dose and type of coagulation factor is not known.

CONCLUSIONS

Vitamin K therapy is an effective treatment for INR prolongation in patients with coumarin-associated coagulopathy; coagulation factor replacement is required, in addition, in patients with major bleeding or with indication for immediate correction of their INR. Clinical trials powered to detect differences in rates of bleeding and thrombosis are now required to determine if vitamin K reduces the risk of bleeding without causing thrombosis in non-bleeding patients with prolonged INR.

Individualized dosing regimen for prothrombin complex concentrate more effective than standard treatment in the reversal of oral anticoagulant therapy: An open, prospective randomized controlled trial

Prothrombin Complex Concentrate (PCC) is indicated for the acute reversal of oral anticoagulation therapy. To compare the efficacy of a "standard" dosage of 20 ml PCC equivalent to about 500 IU factor IX (group A), and an "individualized" dosage based on a target-INR of 2.1 or 1.5, the initial-INR and the patient's body weight (group B), we performed an open, prospective, randomized, controlled trial. The in vivo response and in vivo recovery of factor II, VII, IX and X in these patients on oral anticoagulation was determined. Ninety three patients (group A: 47; group B: 46) with major bleedings or admitted for urgent (surgical) interventions were enrolled. PCC and Vitamin K (10 mg) were administered intravenously. We evaluated the effect of treatment by the decrease of INR and the clinical outcome. The number of patients reaching the target-INR 15 min after the dosage of PCC was significantly higher in the group treated with an "individualized" dosage, compared to the group treated with a standard dose, (89% versus 43%; p<0.001). So, we conclude that for the acute reversal of oral anticoagulant therapy, an "individualized" dosage regimen of PCC based on the target-INR, the initial-INR, and body weight of the patient, is significantly more effective in reaching the target-INR than a "standard" dosage. The in vivo response and in vivo recovery found in this study was higher then in patients with isolated factor deficiencies. This suggests that the pharmacokinetics in patients on oral anticoagulants may be different.

DVT prophylaxis and anticoagulation in the surgical patient

One of the most common postoperative complications is venous thromboembolism, a term encompassing deep vein thrombosis and pulmonary embolism. This article reviews the epidemiology, natural history, difficulties in diagnosis, and strategies for the prevention of postoperative venous thromboembolism. We thoroughly review the currently available methods for thromboprophylaxis including: early ambulation, elastic compression stockings, pneumatic compression devices, inferior vena cava filters, and a variety of pharmacologic agents such as unfractionated heparin, warfarin, aspirin, low molecular weight heparin, and pentasaccharides. Finally, we review the perioperative management of patients on long-term oral anticoagulation.

Recombinant factor VIIa (Novoseven) restores deficient coagulation: experience from an ex vivo model

The action of recombinant factor VIIa (rFVIIa) in coagulation deficiencies with increased risk of bleeding was investigated using in vitro perfusion. Blood samples were drawn from healthy donors, a patient with hemophilia A and inhibitors, and six patients undergoing oral anticoagulant treatment. Fragmin 10 U/mL was used as anticoagulant. rFVIIa (10 microg/mL in plasma) was added to blood samples, incubated for 1 minute at 37 degrees C, and perfusion studies performed for 10 minutes at 600 x s(-1) through annular chambers containing damaged vascular segments. Subendothelial fibrin and platelets were expressed as a percentage of subendothelial surface screened. Under different conditions, rFVIIa consistently restored or improved fibrin formation on the damaged vascular subendothelium exposed to circulating blood. It restored fibrin deposition in blood from the hemophilia A patient; in patients undergoing acenocoumarol treatment, it reduced the international normalized ratio (INR) from 2.47 to 1.25 with a significant increase in fibrin deposition. Platelet deposition varied slightly between clinical conditions but was less evident in the hemophilia A patient. These data support the concept that rFVIIa facilitates fibrin formation in these clinical situations, promoting procoagulant activity at sites of vascular damage where tissue factor is exposed. This could improve hemostasis in patients with hemophilia A and inhibitors, and in patients treated with oral anticoagulants.

Vitamin K to reverse excessive anticoagulation: a review of the literature

We conducted an extensive literature review to evaluate the appropriate use, route, and dose of vitamin K to reverse excessive anticoagulation. Issues such as sample size, study design, different patient populations, and various study end points confounded results. Of 18 studies published, 8 enrolled 229 patients to evaluate parenteral vitamin K administration. Nine studies with 288 patients evaluated oral administration, and only 2 retrospective studies (280 patients) compared routes of administration. Reductions in international normalized ratios at 24 hours ranged from 21-42%, 47-86%, 25-67%, and 40-75% for temporary warfarin discontinuation alone, and intravenous, subcutaneous, and oral routes of vitamin K administration, respectively. Methodologically weak studies and indeterminate results plague interpretation of the literature on vitamin K. In general, results of this review support current guidelines for reversing excessive warfarin anticoagulation. However, it is important to realize that the quality of literature on which these recommendations are based is poor and that optimal dose and route of vitamin K administration remain unclear. Large, well-designed, randomized, controlled trials are necessary to define optimum management strategies for excessively anticoagulated patients.

The use of prothrombin complex concentrates in the treatment of hemorrhages induced by oral anticoagulation

Bleeding events are a common adverse effect in oral anticoagulation that frequently depend on the duration and intensity of treatment. Major bleeding events, particularly intracerebral hemorrhages, are a serious complication in cases that require the rapid reversal of anticoagulation. Urgent correction of the coagulation defect is also indicated when major emergency surgery is necessary. In addition to vitamin K supplementation, the administration of prothrombin complex concentrates is the most effective measure for the rapid reversal of anticoagulation. Due to the time-consuming administration and increased risk of volume overload, the administration of fresh frozen plasma is less advisable in such instances. The application of prothrombin complex concentrates requires a precautious risk-benefit evaluation, including an estimation of contraindications and repeated laboratory monitoring for dose adjustment.

Management of oral anticoagulant-induced intracranial haemorrhage

Intracranial haemorrhage is an infrequent but often fatal complication of oral anticoagulant therapy which will become more common as anticoagulant use increases. The risk of anticoagulant-induced intracranial haemorrhage may be reduced by judicious prescribing, identification of patients at high risk of bleeding, and close monitoring by experienced staff. The presenting features of intracranial haemorrhage are often vague and physicians should be aware of the need for urgent investigation of all anticoagulated patients with neurological symptoms. Current guidelines for immediate reversal of anticoagulation recommend administration of vitamin K1 and factor replacement with either factor concentrates or fresh frozen plasma. In this review we discuss recent evidence suggesting prothrombin complex concentrates lead to faster, and more complete, correction of coagulation and, in the context of intracranial bleeding, may be associated with improved neurological status. Evidence for the risks of short-term cessation of anticoagulants, in the immediate period following an intracranial haemorrhage, and their subsequent reintroduction is also discussed.