Dabigatran: how the drug company withheld important analyses

Apixaban plasma concentrations in patients with obesity

PURPOSE

Routine therapeutic drug monitoring of apixaban is currently not recommended but may however be warranted in some situations and for some patient groups to provide better and safer treatment. Due to limited data on apixaban concentrations in different subpopulations, it is still unclear which group of patients could possibly gain from monitoring. The purpose of this study was to examine apixaban exposure in patients with obesity compared with normal-weight patients.

METHODS

Forty patients with obesity (mean BMI 39.4 kg/m2) and 40 controls with normal weight (mean BMI 23.4 kg/m2), treated with apixaban 5 mg twice daily were included. The patients were matched for age, sex, and renal function. Trough and peak apixaban concentrations were measured with LC‒MS/MS methodology.

RESULTS

The median trough concentrations in patients with obesity (58.7, range 10.7-200.7 ng/ml) were slightly higher than those in patients with normal weight (52.0, range 31.0-150.9 ng/ml) (p < 0.05). Notably, the variability in trough concentration was considerably higher in patients with obesity. Peak concentrations were similar in both groups, with a median of 124.5 ng/ml (range 82.0-277.5) and 113.5 ng/ml (range 75.5-334.6) in patients with obesity and normal weight, respectively.

CONCLUSION

Apixaban exposure did not vary substantially between obese and normal weight matched controls, implying that general dose adjustments are not required. However, vast interindividual variability was observed in patients with obesity, suggesting that measuring the concentrations could be valuable for specific patients. Further research is needed to identify which specific patients may benefit from this approach.

Adherence to WHO Criteria on Drug Promotion Literature: An Exploratory Study From a Tertiary Healthcare Facility in South-West Nigeria

Introduction: In many low and middle-income countries (LMIC), drug promotional literature (DPL) remains one of the main sources of drug information for physicians. Studies conducted in many LMICs showed poor compliance to the WHO guidelines for ethical drug promotion especially in the area of information about excipients, adverse drug reactions, drug-drug interactions and contra-indications. These inadequacies in the information provided may mislead the prescriber with potential adverse consequences among patients using the medicines. Nigeria has a big pharmaceutical sector which is poorly regulated and we hypothesize that such unethical drug promotional practices may exist. This study therefore set out to assess compliance to the WHO ethical drug promotion (using DPL) at the Ekiti State University Teaching Hospital (EKSUTH), Ado-Ekiti, South-West Nigeria. Methodology: This was a descriptive cross-sectional study conducted in several specialist clinics of EKSUTH, Ado-Ekiti. Printed DPLs (brochures and leaflets) were collected from these clinics, collated using a pre-designed data collection form and analyzed using the WHO ethical criteria for medicinal drug promotion. Results:Two hundred seventy-five DPLs were screened A total of out of which 234 DPLs were selected after screening to after removal of duplications. Only 5 (2.1%) DPLs met all the WHO criteria. DPLs promoting antibiotics, cardiovascular drugs, and vitamins/nutritional supplements were in the majority (22.2%, 17.1%, and 11.5% respectively. Most of the DPLs had the generic (223; 95.3%) and brand (234; 100%) names, active ingredients (209; 89.3%), excipients (149; 63.7%), and indications (232; 99.1%). Information about adverse drug reactions (76; 32.5%), contra-indications (73; 31.2%), and drug interactions (46; 19.7%) was less represented. Only 59 (25.2%) DPLs had references. Fixed-dose combination drugs made up 34.6% of drugs being promoted. Conclusion:The DPLs assessed in this study had low adherence to WHO ethical drug promotion criteria especially those related to adverse drug reaction, drug interactions, and contra-indications.

Assessment of exposure to direct oral anticoagulants in elderly hospitalised patients

It is unclear whether elderly patients established on direct oral anticoagulants (DOACs) have greater exposure to these drugs, which could subsequently increase their risk of bleeding. We assessed DOAC exposure and factors affecting it in a real-world elderly cohort of patients. For this, 151 medically stable hospital inpatients (76 established on apixaban, 61 on rivaroxaban, 14 on dabigatran) with a median [interquartile range (IQR)] age of 84 (78-89) years were recruited. Patients provided blood samples for measurement of peak and trough plasma DOAC concentrations. There was up to 48-fold and 13-fold variation in trough and peak plasma drug concentrations respectively. A significantly greater proportion of patients on apixaban had peak plasma drug concentrations within the reported ranges compared to those on either rivaroxaban or dabigatran (82·9% vs. 44·3% vs. 64·3% respectively; P < 0·001). A third of the variability in DOAC plasma concentrations was attributed to the influences of DOAC dosage, renal function and gender. To what extent the observed increases in DOAC exposure in the older patients is the cause of their increased risk of bleeding, which could potentially be ameliorated by dosing titration, requires further investigation.

Evidence-based public policy making for medicines across countries: findings and implications for the future

Aim: Global expenditure on medicines is rising up to 6% per year driven by increasing prevalence of non-communicable diseases (NCDs) and new premium priced medicines for cancer, orphan diseases and other complex areas. This is difficult to sustain without reforms. Methods: Extensive narrative review of published papers and contextualizing the findings to provide future guidance. Results: New models are being introduced to improve the managed entry of new medicines including managed entry agreements, fair pricing approaches and monitoring prescribing against agreed guidance. Multiple measures have also successfully been introduced to improve the prescribing of established medicines. This includes encouraging greater prescribing of generics and biosimilars versus originators and patented medicines in a class to conserve resources without compromising care. In addition, reducing inappropriate antibiotic utilization. Typically, multiple measures are the most effective. Conclusion: Multiple measures will be needed to attain and retain universal healthcare.

Real-World Prevalence of Direct Oral Anticoagulant Off-Label Doses in Atrial Fibrillation: An Epidemiological Meta-Analysis

Background: The use of direct oral anticoagulant (DOAC) off-label doses in atrial fibrillation (AF) patients may result in poor clinical outcomes. However, the true prevalence remains scarce. This study aims at estimating the prevalence of DOAC off-label doses in AF patients.

Methods: Databases of MEDLINE, EMBASE, and COCHRANE were searched from inception through February 2020 for real-world studies that reported the off-label definition and prevalence data of AF patients using DOACs. The primacy outcomes were the overall prevalence of DOAC off-label doses and the corresponding underdose and overdose. The random-effects model was used for data synthesis. Variations on individual DOAC and different regions were examined by subgroup analyses.

Results: A total of 23 studies involving 162,474 AF patients were finally included. The overall prevalence of DOAC off-label doses was 24% (95% CI, 19–28%), with 18% for dabigatran, 27% for rivaroxaban, 24% for apixaban, and 26% for edoxaban. The prevalence of underdosed DOACs was 20% (95% CI, 16–24%) with significant difference among individual anticoagulants (13% for dabigatran, 22% for rivaroxaban, 22% for apixaban, and 18% for edoxaban; P_interaction=0.02). The prevalence of overdosed DOACs was 5% (95% CI, 3–7%), with the lowest prevalence observed in apixaban (2%). Subgroup analyses by regions demonstrated that the prevalence of DOAC off-label doses was higher in Asia (32%) than in North America (14%) and in Europe (22%), with underdose being predominant. Regardless of different regions, the prevalence of overdose was relatively low (4–6%).

Conclusion: This study provides an estimation of DOAC off-label doses in the real-world setting. The prevalence rate of DOAC off-label doses in AF patients was relatively high, with underdose being predominant. Clinicians in Asia preferred to prescribe underdose of DOACs to AF patients. More evidence about the appropriateness of DOAC off-label doses in AF patients is urgently needed. Education programs concerning the appropriate prescription of DOACs within the drug labels and accepted guidelines are necessary to DOAC prescribers to ensure the safety and effectiveness of anticoagulation therapy for patients with AF.

Ignoring instead of chasing after coagulation factor VII during warfarin management: an interrupted time series study

During warfarin management, variability in prothrombin time-based international normalized ratio (PT-INR) is caused, in part, by clinically inconsequential fluctuations in factor VII (FVII). The new factor II and X (Fiix)-prothrombin time (Fiix-PT) and Fiix-normalized ratio (Fiix-NR), unlike PT-INR, are only affected by reduced FII and FX. We assessed the incidence of thromboembolism (TE) and major bleeding (MB) in all 2667 patients on maintenance-phase warfarin managed at our anticoagulation management service during 30 months; 12 months prior to and 18 months after replacing PT-INR monitoring with Fiix-NR monitoring. Months 13 to 18 were predefined as transitional months. Using 2-segmented regression, a breakpoint in the monthly incidence of TE became evident 6 months after test replacement, that was followed by a 56% reduction in incidence (from 2.82% to 1.23% per patient-year; P = .019). Three-segmented regression did not find any significant trend in TE incidence (slope, +0.03) prior to test replacement; however, during months 13 to 18 and 19 to 30, the incidence of TE decreased gradually (slope, -0.12; R2 = 0.20; P = .007). The incidence of MB (2.79% per patient-year) did not differ. Incidence comparison during the 12-month Fiix and PT periods confirmed a statistically significant reduction (55-62%) in TE. Fiix monitoring reduced testing, dose adjustments, and normalized ratio variability and prolonged testing intervals and time in range. We conclude that ignoring FVII during Fiix-NR monitoring in real-world practice stabilizes the anticoagulant effect of warfarin and associates with a major reduction in TEs without increasing bleeding.

Improving anticoagulation in sub-Saharan Africa: What are the challenges and how can we overcome them?

Patients in sub-Saharan Africa generally have poor anticoagulation control. We review the potential reasons for this poor control, as well as the potential solutions. Challenges include the affordability and centralisation of anticoagulation care, problems with access to medicines and international normalised ratio monitoring, the lack of locally validated standardized dosing protocols, and low levels of anticoagulation knowledge among healthcare workers and patients. Increasing numbers of patients will need anticoagulation in the future because of the increasing burden of noncommunicable disease in the region. We propose that locally developed "warfarin care bundles" which address multiple anticoagulation challenges in combination may be the most appropriate solution in this setting currently.

The prescription of direct oral anticoagulants in the elderly: An observational study of 19 798 Ambulatory subjects

OBJECTIVE

Direct oral anticoagulants (DOACs) are increasingly prescribed to elderly people, but the epidemiologic data for this population remains scarce. We compared the elderly population taking DOACs and those not taking DOACs (noDOAC).

METHOD

We included individuals over 75 years old, affiliated to Mutualité Sociale Agricole of Burgundy (a French regional health insurance agency), who had been refunded for a prescribed DOAC between 1st and 30th September 2017. The DAOC group (DAOCG) and noDOAC group (noDOACG) were compared in terms of demographic conditions, registered chronic diseases (RCD), and number and types of prescribed drugs. In the DOACG, we compared the type of prescribing physician and laboratory monitoring for novel prescriptions (initial) and prescription refills (≥ 3 months).

RESULTS

Of the 19 798 included patients, 1518 (7.7%) were prescribed DAOCs and 18 280 (92.3%) were not. Mean and median age was 85 years in the 2 groups (DOACG and noDOACG). In the DOACG, there were more men (50% vs 40.2%), more RCD (88.9% vs 68.7%) and more drugs per prescription (6 ± 2.8 vs 5 ± 2.9) (All P < .01). The DOACG also took more antihypertensive drugs. The most commonly prescribed DOACs were apixaban (42.9%) followed by rivaroxaban (38.4%) and dabigatran (18.6%). Complete blood count, serum creatinine and coagulation function tests were requested for 69.4%, 75% and 22.2%, respectively, of patients prescribed DAOCs.

CONCLUSIONS

The DOACG had more RCD and drugs per prescription than the noDOACG; routine laboratory monitoring was insufficient. What's known Platelet aggregation inhibitors (low-dose) are recommended for secondary prevention of cardiovascular events in patients suffering from symptomatic atherosclerosis. The main risk of this treatment is bleeding. What's new A prescription for platelet aggregation inhibitors was found in 34% of geriatric inpatients in this prospective study. Compliance to guidelines was better for symptomatic peripheral artery disease than for primary prevention in accordance with recent publications. Geriatric comorbidities had no impact on the prescription of platelet aggregation inhibitors. Underuse of platelet aggregation inhibitors was observed in 11.3% of cases and overuse in 13.7% of cases.

Acute ICH in patients identified as being treated with either warfarin or direct-acting oral anticoagulant agents (DOACs) from a radiology perspective; a cross-sectional observational of 2359 emergency CT head studies

AIM

To determine and compare the rates of acute intracranial haemorrhage (ICH) in emergency computed tomography (CT) head studies performed on patients treated with either warfarin or a direct-acting oral anticoagulant agent (DOAC) in a real-world acute setting from a radiology service perspective.

METHOD

A retrospective automated search was undertaken via the hospital's radiology information system (RIS) for emergency CT head studies performed over a 2-year period where the clinical details indicated treatment with warfarin or a DOAC. The report of each scan was reviewed for the presence of unequivocal ICH. Duplicate and follow-up scans were excluded. Other parameters (trauma history and time of scan) were also reviewed.

RESULTS

Following exclusions, 2,359 cases were eligible for analysis; 1,822 patients were treated with warfarin and 537 treated with DOACs. One hundred and nineteen CT heads, of which 104 were treated with warfarin and 15 treated with DOACs, were positive for various types of ICH. The positive rate for ICH was lower in the DOACs group than the warfarin group; 2.7% (number needed to scan: 37) versus 5.7% (number needed to scan: 17.5; p=0.0067). This is also true in a cohort of patients who had traumatic head injury; 2.14% (number needed to scan: 46.7) versus 5.80% (number needed to scan: 17.2; p=0.02).

CONCLUSION

The present study has shown a lower rate of ICH in patients treated with DOACs compared to those treated with warfarin in an acute setting. A similar trend is demonstrated in a cohort of patients with a history of traumatic head injury.

Periprocedural management of patients receiving novel oral anticoagulants

Background

Non-vitamin K oral antagonists are being increasingly used. However, broad clinical experience with them is lacking.

Objectives

To review guidelines and evidence for the use of non-vitamin K oral antagonists in the periprocedural environment.

Results

Despite the clear advantages of vitamin K oral antagonists, their use can entail risks owing to the scarcity of reversal agents. Consensus has been reached about postoperative resumption, which is recommended at 24 hours and 48-72 hours, respectively, after low-risk and high-risk bleeding surgery. Bridging with heparin is recommended in patients with a high risk of thrombosis. Urgent interventions should ideally take place 24 hours after the last dose intake. Major discrepancies exist between the American and the European recommendations for neuraxial procedures. The American proposals recommend suspending the drug for five half-lives, whereas the European approaches suggest suspension of just two half-lives. Suggestions for perioperative discontinuation vary widely. Some authors recommend a longer time of resumption for patients with renal impairment. All agree that there should be an increase in the number of days of interruption in high-risk bleeding procedures versus low-risk bleeding procedures.

Conclusions

A diverse number of approaches have been suggested for perioperative management of novel oral antagonists. American recommendations tend to be more rigorous than those of Europe. A need for more studies that measure health outcomes after the use of these drugs would be indispensable.

Effectiveness and Safety of Direct Oral Anticoagulants versus Vitamin K Antagonists for People Aged 75 Years and over with Atrial Fibrillation: A Systematic Review and Meta-Analyses of Observational Studies

Older people, are underrepresented in randomised controlled trials of direct oral anticoagulants (DOACs) for stroke prevention in atrial fibrillation (AF). The aim of this study was to combine data from observational studies to provide evidence for the treatment of people aged ≥75 years. Medline, Embase, Scopus and Web of Science were searched. The primary effectiveness outcome was ischaemic stroke. Safety outcomes were major bleeding, intracranial haemorrhage, gastrointestinal bleeding, myocardial infarction, and mortality. Twenty-two studies were eligible for inclusion. Two studies related specifically to people ≥75 years but were excluded from meta-analysis due to low quality; all data in the meta-analyses were from subgroups. The pooled risk estimate of ischaemic stroke was slightly lower for DOACs. There was no significant difference in major bleeding, mortality, or myocardial infarction. Risk of intracranial haemorrhage was 44% lower with DOACs, but risk of GI bleeding was 46% higher. Our results suggest that DOACs may be preferable for the majority of older patients with AF, provided they are not at significant risk of a GI bleed. However, these results are based entirely on data from subgroup analyses so should be interpreted cautiously. There is a need for adequately powered research in this patient group.

Serum Concentrations and Elimination Rates of Direct-Acting Oral Anticoagulants (DOACs) in Older Hip Fracture Patients Hospitalized for Surgery: A Pilot Study

BACKGROUND

Use of direct-acting oral anticoagulants (DOACs) is increasing, but knowledge about pharmacokinetics and safety in frail patients is lacking.

OBJECTIVE

The aim was to determine serum concentrations and elimination rates of DOACs in older hip fracture patients hospitalized for surgery.

METHODS

The study included patients ≥ 65 years of age hospitalized for acute hip fracture surgery over a period of 6 months. Use of antithrombotic drugs was registered and serum samples collected for analysis of DOACs (apixaban, dabigatran and rivaroxaban) at admission and surgery. Measured concentrations were assessed in relation to reference (therapeutic) ranges of the respective drugs and applied for half-life calculations. Furthermore, waiting time for surgery was compared between DOAC and warfarin users.

RESULTS

Of 167 patients included (median age 84 years), 11 and 14 used DOACs and warfarin, respectively. Seven of the DOAC-treated patients had concentrations above the upper reference range (> 300 nM) at admission, and concentrations were still in the reference range for five of these at surgery. Elimination half-lives could be estimated in eight patients and ranged between 14.6 and 59.7 h (median 21.6). The observed waiting time for surgery was longer for patients using DOACs than warfarin (median 44 vs. 25 h).

CONCLUSION

This pilot study indicates that older patients prone to hip fracture are at risk of being exposed to therapeutic serum concentrations of DOACs during surgery due to reduced drug elimination rates. The observation that almost 50% of the patients had therapeutic concentrations at surgery should be investigated further regarding safety of DOAC use in this frail elderly population.

[Treatment with oral anticoagulants in older patients: Should warfarin still be prescribed?]

Vitamin-K antagonists (VKA) have been the standard for oral anticoagulation. However, they carry several problems in older patients: frequent bleeding complications, complex management, risk of interactions with multiple drugs. Two classes of direct oral anticoagulants (DOA) are currently available in France: (a) direct thrombin inhibitors: dabigatran; and (b) direct factor Xa inhibitors: rivaroxaban, apixaban and others. Their management is easier: quickly effective after administration, they are given at fixed doses and do not need regular laboratory monitoring. Several randomized trials have shown that DOA are non-inferior to VKA for treating venous thromboembolic disease (prophylactic or curative treatment) and atrial fibrillation (prevention of associated embolisms). DOA might be also effective for long-term treatment of coronary disease, in some cases. No trial has specifically studied older patients. In the context of atrial fibrillation, subgroup analysis show similar results between patients above and below 75-years-old. Lower doses of dabigatran and apixaban should be used in many older people. All DOA are eliminated at least partly by kidneys. Their dose must be reduced in moderate renal failure (filtration glomerular rate (FGR) 30 to 50mL/min) and they are contraindicated in older patients with severe renal failure (FGR<30mL/min). DOA also have other problems: (a) important drug interactions are still possible, (b) the clinical application of specific coagulation tests need to be defined, (c) their safety in some subgroups of elderly patients, very different from patients included in clinical trials, is not known.

Barriers for Access to New Medicines: Searching for the Balance Between Rising Costs and Limited Budgets

Introduction: There is continued unmet medical need for new medicines across countries especially for cancer, immunological diseases, and orphan diseases. However, there are growing challenges with funding new medicines at ever increasing prices along with funding increased medicine volumes with the growth in both infectious diseases and non-communicable diseases across countries. This has resulted in the development of new models to better manage the entry of new medicines, new financial models being postulated to finance new medicines as well as strategies to improve prescribing efficiency. However, more needs to be done. Consequently, the primary aim of this paper is to consider potential ways to optimize the use of new medicines balancing rising costs with increasing budgetary pressures to stimulate debate especially from a payer perspective. Methods: A narrative review of pharmaceutical policies and implications, as well as possible developments, based on key publications and initiatives known to the co-authors principally from a health authority perspective. Results: A number of initiatives and approaches have been identified including new models to better manage the entry of new medicines based on three pillars (pre-, peri-, and post-launch activities). Within this, we see the growing role of horizon scanning activities starting up to 36 months before launch, managed entry agreements and post launch follow-up. It is also likely there will be greater scrutiny over the effectiveness and value of new cancer medicines given ever increasing prices. This could include establishing minimum effectiveness targets for premium pricing along with re-evaluating prices as more medicines for cancer lose their patent. There will also be a greater involvement of patients especially with orphan diseases. New initiatives could include a greater role of multicriteria decision analysis, as well as looking at the potential for de-linking research and development from commercial activities to enhance affordability. Conclusion: There are a number of ongoing activities across countries to try and fund new valued medicines whilst attaining or maintaining universal healthcare. Such activities will grow with increasing resource pressures and continued unmet need.

Comparative Effectiveness and Safety of Monoclonal Antibodies (Bevacizumab, Cetuximab, and Panitumumab) in Combination with Chemotherapy for Metastatic Colorectal Cancer: A Systematic Review and Meta-Analysis

BACKGROUND

The last decade has seen the increasing use of biological medicines in combination with chemotherapy containing 5-fluorouracil/oxaliplatin or irinotecan for the treatment of metastatic colorectal cancer (mCRC). These combinations have resulted in increased progression-free survival (PFS) in patients with mCRC; however, there are remaining concerns over the extent of their effect on overall survival (OS). Published studies to date suggest no major differences between the three currently available monoclonal antibodies (MoAbs); however, there are differences in costs. In addition, there is rising litigation in Brazil in order to access these medicines as they are currently not reimbursed.

OBJECTIVE

The aim was to investigate the comparative effectiveness and safety of three MoAbs (bevacizumab, cetuximab and panitumumab) associated with fluoropyrimidine-based chemotherapy regimens and compared to fluoropyrimidine-based chemotherapy alone in patients with mCRC, through an updated systematic review and meta-analysis of concurrent or non-concurrent observational cohort studies, to guide authorities and the judiciary.

METHOD

A systematic review and meta-analysis was performed based on cohort studies published in databases up to November 2017. Effectiveness measures included OS, PFS, post-progression survival (PPS), Response Evaluation Criteria In Solid Tumors (RECIST), response rate, metastasectomy and safety. The methodological quality of the studies was also evaluated.

RESULTS

A total of 21 observational cohort studies were included. There were statistically significant and clinically relevant benefits in patients treated with bevacizumab versus no bevacizumab mainly around OS, PFS, PPS and the metastasectomy rate, but not for the disease control rates. However, there was an increase in treatment-related toxicities and concerns with the heterogeneity of the studies.

CONCLUSION

The results pointed to an advantage in favor of bevacizumab for OS, PFS, PPS, and metastasectomy. Although this advantage may be considered clinically modest, bevacizumab represents a hope for increased survival and a chance of metastasectomy for patients with mCRC. However, there are serious adverse events associated with its use, especially severe hypertension and gastrointestinal perforation, that need to be considered.

Trends and Variation in Oral Anticoagulant Choice in Patients with Atrial Fibrillation, 2010-2017

OBJECTIVE

Since 2010, several non-vitamin K antagonist oral anticoagulants (NOACs) have been brought to the U.S. market, yet little is known regarding their evolving adoption for prophylaxis of atrial fibrillation (AF)-related stroke. We examined temporal trends in choice of oral anticoagulants (OACs) among incident OAC users with AF and its association with patient demographic and clinical characteristics.

METHODS

We conducted a serial cross-sectional analysis of medical and pharmacy claims for commercial and Medicare Advantage enrollees in a large, private, U.S. health plan. We identified 112,187 adults with nonvalvular AF starting OACs between October 2010 and March 2017. Multivariable logistic regression was used to examine the associations of patient characteristics with prescription of NOACs versus warfarin. Multinomial logistic regression was used to test the associations of patient characteristics with choice among NOACs.

RESULTS

The prescription of NOACs has increased dramatically since their introduction in October 2010. In the first quarter of 2017 (2017Q1), 7502 patients started OACs, of whom 78.9% used NOACs and 21.1% warfarin. For NOACs, 3.8% used dabigatran, 25.0% rivaroxaban, and 50.1% apixaban. In multivariable analyses, factors associated with choice of NOACs versus warfarin included younger age, lower stroke or bleeding risk, fewer comorbidities, higher education level or household net worth, and prescription by cardiologists (all p<0.001). There was no sex difference in likelihood of filling NOACs versus warfarin in 2010Q4-2012, but women had higher odds of starting NOACs (odds ratio = 1.19; 95% confidence interval = 1.14-1.25) in 2015-2017Q1. Among NOAC users, the odds of apixaban prescription increased with age, female sex, stroke or bleeding risk, and comorbidities (all p<0.05).

CONCLUSION

NOAC prescriptions have increased substantially among incident OAC users with nonvalvular AF, predominantly driven by increased prescription of apixaban. Warfarin and apixaban were generally preferred for elderly patients, patients with higher stroke or bleeding risk, and patients with more comorbidities.

Drug promotional activities in Nigeria: impact on the prescribing patterns and practices of medical practitioners and the implications

OBJECTIVE

Pharmaceutical companies spend significant amount of resources on promotion influencing the prescribing behavior of physicians. Drug promotion can negatively impact on rational prescribing, which may adversely affect the quality of patient care. However, little is known about these activities in Nigeria as the most populous country in Africa. We therefore aimed to explore the nature of encounters between Nigerian physicians and pharmaceutical sales representatives (PSRs), and how these encounters influence prescribing habits.

METHODS

Cross-sectional questionnaire-based study conducted among practicing physicians working in tertiary hospitals in four regions of Nigeria.

RESULTS

176 questionnaires were completed. 154 respondents (87.5%) had medicines promoted to them in the previous three months, with most encounters taking place in outpatients' clinics (60.2%), clinical meetings (46%) and new medicine launches (17.6%). Information about potential adverse effects and drug interactions was provided in 41.5%, and 27.3% of cases, respectively. Food, in the form of lunch or dinner, was the most common form of incentive (70.5%) given to physicians during promotional activities. 61% of physicians felt motivated to prescribe the drug promoted to them, with the quality of information provided being the driving factor. Most physicians (64.8%) would agree to some form of regulation of the relationship between medical doctors and the pharmaceutical industry.

CONCLUSION

Interaction between PSRs and physicians is a regular occurrence in Nigeria, influencing prescribing practices. Meals and cheap gifts were the most common items offered to physicians during their encounters with PSRs. The need for some form of regulation by professional organizations and the government was expressed by most respondents to address current concerns.

Measurement of dabigatran: previously demonstrated Hemoclot® Thrombin Inhibitor assay reagent instability on Sysmex CS-2100i is no longer an issue

The Hemoclot^® Thrombin Inhibitor (HTI) assay has been recommended for measurement of dabigatran concentrations in specific clinical situations. Traditionally, reagents for biochemical assays are prepared from instructions found in the package insert. For the HTI reagents the manufacturer recommends incubating the reagents much longer than indicated in the package insert. These recommendations are added to the application sheets designed for different analyzers. Many clinicians and laboratory personnel may be unaware of the discrepancy between the two instructions, resulting in incorrect handling of the reagents. The aim of this study was to investigate the effect of the two different preparation methods on reagent stability and test results. For the standard concentration range, reagent stability on Sysmex CS-2100i was only two hours instead of the eight hours indicated by the producer when following package insert instructions (incubation time: 15 min). Stability was increased to five hours when following the application sheet (incubation time: 60 min). Two years later, the study was repeated using samples of patients treated with dabigatran etexilate. This time, reagent stability was at least six hours. Since the reagent composition was unchanged, the increased stability could be due to changed logistics by the supplier, with stock and transfer closer by. Previously demonstrated HTI reagent instability is no longer an issue at our laboratory. The reliability of results of clinical studies in which the assay has been used is potentially compromised.

Initial anticoagulation in patients with pulmonary embolism: thrombolysis, unfractionated heparin, LMWH, fondaparinux, or DOACs?

The initial treatment of haemodynamically stable patients with pulmonary embolism (PE) has dramatically changed since the introduction of low molecular weight heparins (LMWHs). With the recent discovery of the direct oral anticoagulant drugs (DOACs), initial treatment of PE will be simplified even further. In several large clinical trials it has been demonstrated that DOACs are not inferior to standard therapy for the initial treatment of PE, and because of their practicability they are becoming the agents of first choice. However, many relative contraindications to DOACs were exclusion criteria in the clinical trials. Therefore, LMWHs will continue to play an important role in initial PE treatment and in some cases there still is a role for unfractionated heparin (UFH). In this review we will give an overview of the biophysical, pharmacokinetic and pharmacodynamic properties of anticoagulants currently available for the initial management of PE. In addition, we will provide a comprehensive overview of the indications for the use of UFH, LMWHs and DOACs in the initial management of PE from a pharmacokinetic/-dynamic point of view.

Drug therapy in anticoagulation: which drug for which patient?

Four non-vitamin K oral anticoagulants (NOACs) are now licensed and available in the UK, offering unprecedented choices in anticoagulant therapy for clinicians and patients. NOACs have many clear benefits over warfarin, the most striking being the reduction in intracranial haemorrhage. However, a number of uncertainties remain: their efficacy in certain situations, utility of drug assays, significance of drug interactions and management of bleeding. In the absence of any direct comparative trials, it is not clear that any of the NOACs is significantly better than the others in any of the licensed indications. The differential activities, pharmacokinetics, metabolism, excretion and side effects of the agents should be considered when selecting the most appropriate anticoagulant. In this article, we discuss how, with careful selection for the relevant indication, NOACs can simplify therapy while improving outcomes. We aim to provide clinicians with the information needed to select the most suitable anticoagulant drug for an individual patient in a given situation.

Systematic review finds that study data not published in full text articles have unclear impact on meta-analyses results in medical research

BACKGROUND

A meta-analysis as part of a systematic review aims to provide a thorough, comprehensive and unbiased statistical summary of data from the literature. However, relevant study results could be missing from a meta-analysis because of selective publication and inadequate dissemination. If missing outcome data differ systematically from published ones, a meta-analysis will be biased with an inaccurate assessment of the intervention effect. As part of the EU-funded OPEN project (www.open-project.eu) we conducted a systematic review that assessed whether the inclusion of data that were not published at all and/or published only in the grey literature influences pooled effect estimates in meta-analyses and leads to different interpretation.

METHODS AND FINDINGS

Systematic review of published literature (methodological research projects). Four bibliographic databases were searched up to February 2016 without restriction of publication year or language. Methodological research projects were considered eligible for inclusion if they reviewed a cohort of meta-analyses which (i) compared pooled effect estimates of meta-analyses of health care interventions according to publication status of data or (ii) examined whether the inclusion of unpublished or grey literature data impacts the result of a meta-analysis. Seven methodological research projects including 187 meta-analyses comparing pooled treatment effect estimates according to different publication status were identified. Two research projects showed that published data showed larger pooled treatment effects in favour of the intervention than unpublished or grey literature data (Ratio of ORs 1.15, 95% CI 1.04-1.28 and 1.34, 95% CI 1.09-1.66). In the remaining research projects pooled effect estimates and/or overall findings were not significantly changed by the inclusion of unpublished and/or grey literature data. The precision of the pooled estimate was increased with narrower 95% confidence interval.

CONCLUSIONS

Although we may anticipate that systematic reviews and meta-analyses not including unpublished or grey literature study results are likely to overestimate the treatment effects, current empirical research shows that this is only the case in a minority of reviews. Therefore, currently, a meta-analyst should particularly consider time, effort and costs when adding such data to their analysis. Future research is needed to identify which reviews may benefit most from including unpublished or grey data.

A left atrial appendage thrombus that developed during prophylactic low-dose dabigatran treatment resolved after switching to apixaban

We describe a case of atrial fibrillation in which an intracardiac thrombus that could not be prevented with “low‐dose” dabigatran treatment was resolved by switching to apixaban treatment. Thrombolysis using direct oral anticoagulants (DOACs) could be a therapeutic option for patients with intracardiac thrombi, although the efficacies of different DOACs seem to differ and need further examination.

Contribution of industry funded post-marketing studies to drug safety: survey of notifications submitted to regulatory agencies

OBJECTIVES

 To investigate the practice of post-marketing studies in Germany during a three year period and to evaluate whether these trials meet the aims specified in the German Medicinal Products Act.

DESIGN

 Survey of notifications submitted to German regulatory agencies before post-marketing studies were carried out, 2008-10.

SETTING

 Notifications obtained through freedom of information requests to the three authorities responsible for registering post-marketing studies in Germany.

MAIN OUTCOME MEASURES

 Descriptive statistics of post-marketing studies, including the products under study, intended number of patients, intended number of participating physicians, proposed remunerations, study plan and protocol, and availability of associated scientific publications and reports on adverse drug reactions.

RESULTS

 Information was obtained from 558 studies, with a median of 600 (mean 2331, range 2-75 000) patients and 63 (270, 0-7000) participating physicians per study. The median remuneration to physicians per patient was €200 (€441, €0-€7280) (£170, £0-£6200; $215, $0-$7820), with a total remuneration cost of more than €217m for 558 studies registered over the three year period. The median remuneration per participating physician per study was €2000 (mean €19 424), ranging from €0 to €2 080 000. There was a broad range of drugs and non-drug products, of which only a third represented recently approved drugs. In many notifications, data, information, and results were, by contract, strictly confidential and the sole property of the respective sponsor. No single adverse drug reaction report could be identified from any of the 558 post-marketing studies. Less than 1% of studies could be verified as published in scientific journals.

CONCLUSIONS

 Post-marketing studies are not improving drug safety surveillance. Sample sizes are generally too small to allow the detection of rare adverse drug reactions, and many participating physicians are strictly obliged to maintain confidentiality towards the sponsor. High remuneration and strict confidentiality clauses in these studies could influence the physicians' reporting behaviours of adverse drug reactions.

Real life dabigatran and metabolite concentrations, focused on inter-patient variability and assay differences in patients with atrial fibrillation

Background:

Dabigatran is prescribed to increasing numbers of patients with atrial fibrillation (AF). Although routine monitoring is not considered to be useful, measuring drug concentrations can be clinically relevant in specific situations. The aim of this study was the comparison of different functional and non-functional assays for determination of dabigatran concentrations at different timepoints in a real-life patient population with AF. We focused on the differences between assays in identifying patients with low drug concentrations. Furthermore, we studied the effect of glucuronidation on the established concentration as determined with different assays.

Methods:

This study established dabigatran concentration ranges in 40 real-life AF patients by an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) reference method and compared these with results from coagulation assays (Hemoclot dTT, LD-dTT and ECA). Samples were taken just before and 2 and 4 h after taking the drug.

Results:

A wide range of concentrations at different time points was found in this patient group. Coagulation assays correlate best with UPLC-MS/MS results that include the glucuronidated metabolites, showing that the pharmacologically active glucuronides are also measured in coagulation testing. The LD-dTT has the best agreement with UPLC-MS/MS and combines good sensitivity with high specificity. Several patients show consistently low or high drug concentrations, implying that drug exposure differs between patients.

Conclusions:

Based on the association of dabigatran concentrations with bleeding and thromboembolic risk, we believe that dabigatran monitoring could be beneficial for further optimizing anticoagulation therapy in AF.

Non-vitamin K Oral Anticoagulants Versus Warfarin for Patients with Atrial Fibrillation: Absolute Benefit and Harm Assessments Yield Novel Insights

BACKGROUND AND OBJECTIVES

Benefits and/or harms (including costs) of non-vitamin K oral anticoagulants (NOACs) versus warfarin therapy need appreciation in relative and absolute terms.

METHODS

Accordingly, we derived clinically relevant relative and absolute benefit/harm parameters for NOACs (apixaban, dabigatran, rivaroxaban, edoxaban) compared to warfarin from four clinical trials involving atrial fibrillation (AF) patients. For each trial, we tabulated patient numbers enduring four important outcomes and calculated unadjusted relative risk reduction (RRR) and number needed to treat (NNT)/year values (and 95% confidence intervals) for the NAOC compared to warfarin. These outcomes were as follows: stroke/systemic embolism (primary endpoint), hemorrhagic stroke, major bleeds, and death. We also addressed drug acquisition costs.

RESULTS

Each NOAC was noninferior to warfarin for primary-outcome prevention; RRRs were 12-33% and NNT/year values were 182-481, and all but one indicated statistically significant superiority. All the NOACs yielded statistically significant reductions in hemorrhagic stroke risk; RRRs were 42-74% and NNT/year values were 364-528. Major bleeding risk was comparable in both groups. Apixaban yielded a lower NNT/year for preventing death than for primary-outcome prevention. Compared to warfarin, NOAC acquisition costs were 70- to 140-fold greater.

CONCLUSIONS

For the primary outcome, the absolute benefits of NOACs were modest (NNT/year values being large). Reduced hemorrhagic stroke rates with NOACs could be due to superior embolic infarct prevention and fewer consequential hemorrhagic transformations. Among apixaban recipients, the absolute mortality benefit exceeded that for the primary outcome, indicating prevention of additional unrelated deaths. The substantially greater NOAC acquisition costs need viewing against probable greater safety and the avoidance of monitoring bleeding risks.

Reversal Strategies for NOACs: State of Development, Possible Clinical Applications and Future Perspectives

The non-vitamin K antagonist oral anticoagulants (NOACs) are used for thromboembolic prophylaxis of patients with atrial fibrillation and in the treatment as well as secondary prophylaxis of patients with venous thromboembolism. Even though NOACs have a better safety profile than vitamin K antagonists (VKAs), there will still be bleeding complications on NOAC treatment. In some cases, stopping the NOAC and non-drug-related management such as manual compression and interventional endoscopy will be sufficient to stop the bleeding. In more serious bleeding events and before acute surgery, coagulation factor concentrates or NOAC-specific antidotes could be used. Coagulation factor concentrates can be used in patients with haemophilia and to reverse the effect of VKAs but, in NOAC-treated patients, results are inconsistent and these agents could potentially have pro-thrombotic effects. Specific antidotes for NOACs are expected to be on the market soon. Phase III clinical trials with a humanized antibody fragment directed against dabigatran (idarucizumab) and recombinant, modified factor Xa (andexanet alfa) are ongoing. A molecule (aripazine) with broad activity against various anticoagulants including NOACs is currently undergoing phase II trials. For use of these specific antidotes, it is desirable that measurements for coagulation activity with a short response delay are widely available for the different NOACs and further research in this field is needed. Furthermore, guidelines for antidote use, including general measures for the treatment of NOAC-related bleeding, should be available.

Fostering Competence in Medicines Development: The IFAPP Perspective

IFAPP (International Federation of Associations of Pharmaceutical Physicians and Pharmaceutical Medicine) is a nonprofit organization with the mission to promote Pharmaceutical Medicine & Medicines Development (PM&MD) by enhancing the competencies and maintaining high research ethical standards of Pharmaceutical Physicians and other professionals involved in medicines development worldwide, leading to the availability and appropriate use of medicines for the benefit of patients and society¹. About 30 national professional associations related to PM&MD, involving 7000 professionals, are affiliated to IFAPP. Medicines development has traditionally been a challenging enterprise, with high risk, high investment, and potentially high returns in the lengthy and complex process of identifying a new chemical entity as a candidate for development and possibly succeeding in bringing it as a pharmaceutical product to the market. However, the emergence of genomics, translational research, biomarkers, and precision medicine pose challenges going forward involving allocation of resources, price, market access, and cost-effectiveness as opposed to the traditional concepts of “efficacy” and “safety.” Education and Continuing Professional Development (CPD) are a major focus of IFAPP. The International Conference on Pharmaceutical Medicine (ICPM) is the largest event for our organization; ICPM is held every 2 or 3 years and is aimed to provide the state of the art in key areas for our discipline and profession. The paper is a reflection on the role of competency-based education and training for Pharmaceutical Physicians and medicines development scientists, as was discussed during the recent ICPM 2016 held in Sao Paulo, Brazil on April 18–19, with the support of the Brazilian Association of Pharmaceutical Medicine, and gathered around 200 representatives from the pharmaceutical, clinical research and regulatory arenas from all over the world^2,3.

An update on the pharmaceutical management of thrombosis

INTRODUCTION

Anticoagulants such as heparins and vitamin K antagonists (VKA) are effective for thrombosis prevention and treatment, but are associated with the risk of bleeding and other limitations, spurring the search for improved drugs. Areas covered: to evaluate the newer anticoagulants, focusing on those tested in phase III clinical trials such as direct oral anticoagulants (DOACs), antisense oligonucleotides (ASO) and warfarin analogues. DOACs such as dabigatran, rivaroxaban, apixaban and edoxaban are licensed for stroke prevention in atrial fibrillation and treatment of venous thromboembolism, dabigatran, rivaroxaban and apixaban for postoperative thromboprophylaxis in patients undergoing elective hip or knee arthroplasty and rivaroxaban for secondary prevention of acute coronary syndromes. ASO interfering with Factor XI hepatic synthesis were effective and safe for thromboprophylaxis in elective knee arthroplasty. Expert opinion: DOACs have overcome some limitations of anticoagulants such as VKA, but are still associated with a risk of bleeding and they lack both standardized and widely available tests measuring their anticoagulant effect and a reversal agent, except for idarucizumab, specific for dabigatran, in case of major or life threatening bleeding or emergency surgery. Agents targeting Factor XI and possibly Factor XII may be ideal anticoagulants, as they can prevent thrombosis with low bleeding risk.

New Oral Anticoagulants and Their Reversal Agents

OPINION STATEMENT

Direct oral anticoagulants (DOAC) are an attractive therapeutic option for anticoagulant treatment in the setting of venous thromboembolism or non-valvular atrial fibrillation. These drugs overall appear to have a lower risk of life-threatening hemorrhage than the vitamin K antagonists. In addition, they demonstrate more predictable and stable pharmacokinetics. Measurement of the degree of anticoagulation is desirable in patients with DOAC-associated hemorrhage, but commonly available coagulation assays show poor sensitivity for degree of DOAC effect. DOAC-specific tests are time consuming and not widely available. All coagulation tests should be interpreted considering the timing of last intake and renal function. When life-threatening bleeding occurs, hemostasis should be restored as rapidly as possible. Non-specific prohemostatic drugs may have a role in DOAC reversal, and specific antidotes are at different stages of development. In this review, we provide a summary of DOAC characteristics and an overview of the different therapeutic options available for DOAC reversal.

Payers' Views of the Changes Arising through the Possible Adoption of Adaptive Pathways

Payers are a major stakeholder in any considerations and initiatives concerning adaptive licensing of new medicinal products, also referred to as Medicines Adaptive Pathways to patients (MAPPs). Firstly, the scope and necessity of MAPPs need further scrutiny, especially with regard to the definition of unmet need. Conditional approval pathways already exist for new medicines for seriously debilitating or life-threatening diseases and only a limited number of new medicines are innovative. Secondly, MAPPs will result in new medicines on the market with limited evidence about their effectiveness and safety. Additional data are to be collected after approval. Consequently, adaptive pathways may increase the risk of exposing patients to ineffective or unsafe medicines. We have already seen medicines approved conventionally that subsequently proved ineffective or unsafe amongst a wider, more co-morbid population as well as medicines that could have been considered for approval under MAPPs but subsequently proved ineffective or unsafe in Phase III trials and were never licensed. Thirdly, MAPPs also put high demands on payers. Routine collection of patient level data is difficult with high transaction costs. It is not clear who will fund these. Other challenges for payers include shifts in the risk governance framework, implications for evaluation and HTA, increased complexity of setting prices, difficulty with ensuring equity in the allocation of resources, definition of responsibility and liability and implementation of stratified use. Exit strategies also need to be agreed in advance, including price reductions, rebates, or reimbursement withdrawals when price premiums are not justified. These issues and concerns will be discussed in detail including potential ways forward.

The other side of the coin: Harm due to the non-use of health-related data

INTRODUCTION

It is widely acknowledged that breaches and misuses of health-related data can have serious implications and consequently they often carry penalties. However, harm due to the omission of health data usage, or data non-use, is a subject that lacks attention. A better understanding of this 'other side of the coin' is required before it can be addressed effectively.

APPROACH

This article uses an international case study approach to explore why data non-use is difficult to ascertain, the sources and types of health-related data non-use, its implications for citizens and society and some of the reasons it occurs. It does this by focussing on issues with clinical care records, research data and governance frameworks and associated examples of non-use.

RESULTS AND DISCUSSION

The non-use of health-related data is a complex issue with multiple explanations. Individual instances of data non-use can be associated with harm, but taken together, they can describe a trail of data non-use that may complicate and compound its impacts. There is ample indirect evidence that health data non-use is implicated in the deaths of many thousands of people and potentially £billions in financial burdens to societies.

CONCLUSIONS

Harm due to the non-use of health data is difficult to attribute unequivocally and actual proven evidence is sparse. Although it can be elusive, it is nevertheless a real problem with widespread and serious, if largely unquantifiable, consequences. The most effective initiatives to address specific contexts of data non-use will be those that: firstly, understand the pertinent sources, types and reasons for data non-use in a given domain in order to meet the challenges and create appropriate incentives and repercussions; and secondly, are cognisant of the multiple aspects to this complex issue in other domains to keep benefits and limitations in perspective, to move steadily towards socially responsible reuse of data becoming the norm to save lives and resources.

Reporting of Adverse Events in Published and Unpublished Studies of Health Care Interventions: A Systematic Review

BACKGROUND

We performed a systematic review to assess whether we can quantify the underreporting of adverse events (AEs) in the published medical literature documenting the results of clinical trials as compared with other nonpublished sources, and whether we can measure the impact this underreporting has on systematic reviews of adverse events.

METHODS AND FINDINGS

Studies were identified from 15 databases (including MEDLINE and Embase) and by handsearching, reference checking, internet searches, and contacting experts. The last database searches were conducted in July 2016. There were 28 methodological evaluations that met the inclusion criteria. Of these, 9 studies compared the proportion of trials reporting adverse events by publication status. The median percentage of published documents with adverse events information was 46% compared to 95% in the corresponding unpublished documents. There was a similar pattern with unmatched studies, for which 43% of published studies contained adverse events information compared to 83% of unpublished studies. A total of 11 studies compared the numbers of adverse events in matched published and unpublished documents. The percentage of adverse events that would have been missed had each analysis relied only on the published versions varied between 43% and 100%, with a median of 64%. Within these 11 studies, 24 comparisons of named adverse events such as death, suicide, or respiratory adverse events were undertaken. In 18 of the 24 comparisons, the number of named adverse events was higher in unpublished than published documents. Additionally, 2 other studies demonstrated that there are substantially more types of adverse events reported in matched unpublished than published documents. There were 20 meta-analyses that reported the odds ratios (ORs) and/or risk ratios (RRs) for adverse events with and without unpublished data. Inclusion of unpublished data increased the precision of the pooled estimates (narrower 95% confidence intervals) in 15 of the 20 pooled analyses, but did not markedly change the direction or statistical significance of the risk in most cases. The main limitations of this review are that the included case examples represent only a small number amongst thousands of meta-analyses of harms and that the included studies may suffer from publication bias, whereby substantial differences between published and unpublished data are more likely to be published.

CONCLUSIONS

There is strong evidence that much of the information on adverse events remains unpublished and that the number and range of adverse events is higher in unpublished than in published versions of the same study. The inclusion of unpublished data can also reduce the imprecision of pooled effect estimates during meta-analysis of adverse events.

Bleeding in patients with atrial fibrillation treated with dabigatran, rivaroxaban or warfarin: A retrospective population-based cohort study

BACKGOUND

Randomized controlled trials (RCTs) have shown that dabigatran, rivaroxaban and warfarin cause similar bleeding rates.

METHODS

We performed a retrospective population-based cohort study to determine the incidence of bleeding in patients with atrial fibrillation (AF) beginning dabigatran, rivaroxaban or warfarin. Consecutive patients initiating anticoagulation for AF during a 3year period were identified using a computerized database. Patients who bled and required hospitalization underwent chart review. Bleeding incidences were calculated per 100 patient-years of treatment.

RESULTS

18,249 patients were included: 9564 (52.4%) received warfarin, 5976 (32.7%) dabigatran, and 2709 (14.8%) rivaroxaban. Bleeding incidences were 3.9 (95% CI, 3.6-4.4) in warfarin-treated patients, 4.2 (95% CI, 3.7-4.7) in dabigatran patients, and 4.1 (95% CI, 3.0-5.3) in rivaroxaban patients. Intracranial hemorrhage (ICH) rates were 0.71 (95% CI, 0.56-0.90) for warfarin, 0.4 (95% CI, 0.18-0.87) for dabigatran, and 0.27 (95%CI, 0.10-0.80) for rivaroxaban. GI hemorrhage rates were 1.88 (95%CI, 1.62-2.20) for warfarin, 2.98 (95% CI, 2.4-3.5) for dabigatran and 2.39 (95%CI, 1.6-3.5) for rivaroxaban.

CONCLUSIONS

We demonstrate similar bleeding rates with both dabigatran 150mg and 110mg and rivaroxaban compared to warfarin.

Measuring non-vitamin K antagonist oral anticoagulant levels: When is it appropriate and which methods should be used?

Background

Although the need for an emergency intervention may merit laboratory measurement of non-vitamin K antagonist oral anticoagulant (NOAC) concentration or anticoagulant activity, NOACs are not supposed to require routine monitoring due to their stable pharmacological profiles compared with warfarin.

Aims

To examine situations where NOAC measurement may be useful and to provide information about methodologies available to measure NOAC-related anticoagulation activity.

Summary of review

The routine coagulation tests, including prothrombin time, thrombin time, activated partial thromboplastin time, and international normalized ratio, have variable sensitivities to NOACs. Tests have been developed for use with specific NOACs, e.g. diluted thrombin time or chromogenic factor Xa assays. In emergency situations, such as severe bleeding, stroke, or a requirement for urgent surgery or procedures, there may be a need to assess anticoagulant activity to guide clinical decision making. In cases where neutralization of the anticoagulant effect is warranted, specific reversal agents are likely to become invaluable medical tools. Evidence to date suggests that dosing decisions for NOACs based on clinical features (e.g. age or renal function) can help optimize the benefit–risk balance without assessment of anticoagulant activity in non-emergency routine situations.

Conclusions

Regular monitoring of NOAC levels does not provide benefits and cannot be recommended at present. In some specific circumstances, e.g. severe bleeding, before urgent surgery, or before thrombolysis, measurement may be beneficial to assess whether a patient is actively anticoagulated. The availability of NOAC-specific reversal agents may change management practices in emergencies.

Faster drug approval: challenges for safety

INTRODUCTION

More rapid drug premarketing procedures pose a challenge for regulatory agencies in terms of innovation and improving real-world safety and effectiveness Areas covered: This review considers the blockbuster drugs used over the previous fifteen years with adverse reactions after marketing, the elements and time span of risk identification and the measures implemented or considered, based on the existing literature and reports from the agencies Expert opinion: Risk prediction is founded on several factors: randomization, sample size, a well-established endpoint for safety, use of a comparator rather than placebo and a longer Phase-III period, in which a serious illness may be identified by early signs of alteration in the primary parenchyma with the latest biochemical, instrumental and imaging techniques. In comparative non-inferiority evaluations, increased safety should be preferred, with the exception of drugs that may be useful in serious or life-threatening diseases for which there are few or no effective existing therapies. A period of restricted use may be required to test and dispense new drugs, as well as to implement specific methods for the early detection of adverse events. It is important not to regard a new medicine axiomatically as the best treatment before it comes into wide use.

Evaluation of the chromogenic anti-factor IIa assay to assess dabigatran exposure in geriatric patients with atrial fibrillation in an outpatient setting

Background

Dabigatran etexilate may be underutilized in geriatric patients because of inadequate clinical experience in individuals with severe renal impairment and post-marketing reports of bleeding events. Assessing the degree of anticoagulation may improve the risk:benefit ratio for dabigatran. The aim of this prospective study was to identify whether therapeutic drug monitoring of dabigatran anticoagulant activity using a chromogenic anti-factor IIa assay is a viable option for therapy individualization.

Methods

Plasma dabigatran concentration was assessed in nine patients with nonvalvular atrial fibrillation aged 75 years or older currently receiving dabigatran etexilate for prevention of stroke, using an anti-factor IIa chromogenic assay and HPLC-MS/MS. Trough concentrations were evaluated on two separate occasions to determine intrapatient variation.

Results

Blood was collected at 13.1 ± 2.3 h (mean ± SD) post dose from patients prescribed dabigatran etexilate 150 mg twice daily (5/9 patients) or dabigatran etexilate 75 mg twice daily (4/9 patients). Results from the anti-factor IIa chromogenic assay correlated with dabigatran concentrations as assessed by HPLC-MS/MS (r² = 0.81, n = 16). There was no correlation between dabigatran trough values taken at separate visits (r² = 0.002, n = 7). Furthermore, there was no correlation found between the drug concentrations and patients’ renal function determined by both creatinine and cystatin-C based equations. None of the patients enrolled in the study were in the proposed on-therapy trough range during at least one visit.

Conclusion

The chromogenic anti-factor IIa assay demonstrated similar performance in quantifying dabigatran plasma trough concentrations to HPLC-MS/MS. Single measurement of dabigatran concentration by either of two methods during routine visits may not be reliable in identifying patients at consistently low or high dabigatran concentrations.

Electronic supplementary material

The online version of this article (doi:10.1186/s12959-016-0084-2) contains supplementary material, which is available to authorized users.

A single test to assay warfarin, dabigatran, rivaroxaban, apixaban, unfractionated heparin, and enoxaparin in plasma

Essentials Simple and fast assaying of different anticoagulants (ACs) is useful in emergent situations. We used highly diluted prothrombin time (dPT) or highly diluted Fiix-PT (dFiix-PT) to assay ACs. Both tests could quantify target specific anticoagulants and warfarin anticoagulation. Improved results were consistently observed with the dFiix-PT compared with the dPT.

SUMMARY

Background Assaying anticoagulants is useful in emergency situations or before surgery. Different specific assays are currently needed depending on the anticoagulant. Objectives We hypothesized that levels of warfarin, dabigatran, rivaroxaban, apixaban, and heparins could be measured with use of the diluted prothrombin time (dPT) and diluted Fiix-PT (dFiix-PT), using highly diluted thromboplastin (TP). The latter test is affected only by reduced levels of active factors II and X but corrects test plasma for other deficiencies Methods Increasing TP dilutions were used to identify suitable dilutions to measure dabigatran, rivaroxaban, apixaban, unfractionated heparin (UFH), and enoxaparin. Calibrators containing known amounts of direct oral anticoagulants (DOACs) were used to make standard curves. Citrated plasma samples were obtained from patients taking warfarin or DOACs with known drug concentrations as determined by specific assays. Results The dFiix-PT at a TP dilution of 1:1156 could be used to measure all of the drugs tested at therapeutic concentrations except for fondaparinux. The dPT achieved the same but required two TP dilutions (1:750 and 1:300). The warfarin effect could be assessed by using dFiix-PT at 1:1156 with a PT ratio identical to the international normalized ratio. Six different TPs yielded similar results, but two were less sensitive. Dabigatran, rivaroxaban, and apixaban could be accurately measured in patient samples using both dilute PT assays, but a better correlation was consistently observed between the dFiix-PT and specific assays than with the dPT. Conclusion The dFiix-PT using a single dilution of TP may be suitable to assess the anticoagulant effects of warfarin, dabigatran, rivaroxaban, apixaban, heparin, and enoxaparin.

Novel Oral Anticoagulants and the Risk of Major Hemorrhage in Elderly Patients With Chronic Kidney Disease: A Nested Case-Control Study

BACKGROUND

The novel oral anticoagulants, including dabigatran and rivaroxaban, differ in their degree of renal excretion.

METHODS

We conducted a population-based nested case-control study in patients 66 years and older with chronic kidney disease (CKD) (excluding patients undergoing chronic dialysis) who received an oral anticoagulant between April 2006 and March 2013. We calculated odds ratios for hospitalization with a major hemorrhagic event and receipt of dabigatran, rivaroxaban, or warfarin in the preceding 60 days. We also performed a sensitivity analysis to investigate whether a relationship exists between major hemorrhage and advanced age (age < 80 years or ≥ 80 years).

RESULTS

We identified 237,409 patients with CKD, 4470 (1.9%) of whom experienced a major hemorrhage. We matched these patients to 14,460 controls. The use of dabigatran or rivaroxaban was not associated with a statistically significant elevated risk of hemorrhage compared with warfarin (adjusted odds ratio [aOR], 1.15; 95% confidence interval [CI], 0.91-1.45 for dabigatran; aOR, 1.22; 95% CI, 0.83-1.79 for rivaroxaban). Our sensitivity analysis found that older age was associated with an increased risk of hemorrhage for patients receiving dabigatran (aOR, 1.41; 95% CI, 1.06-1.88); results were similar but did not reach statistical significance for rivaroxaban (aOR, 1.57; 95% CI, 0.91-2.69).

CONCLUSIONS

Among elderly patients with CKD, exposure to dabigatran or rivaroxaban was not associated with a statistically significant increased risk of major hemorrhagic events compared with exposure to warfarin.

Enhanced elimination of dabigatran through extracorporeal methods

Several pharmacokinetic studies have suggested that dabigatran possesses a number of ideal properties for expedited removal via extracorporeal methods. However, this practice has not been prospectively evaluated in patients with life-threatening bleeding or requiring emergency surgery secondary to dabigatran-associated coagulopathy. The purpose of this literature review is to evaluate the published evidence surrounding extracorporeal removal of dabigatran in the setting of emergency surgery or life-threatening bleeding. A query of MEDLINE, Web of Science, International Pharmaceutical Abstracts, and Google Scholar using the terms dabigatran, dabigatran etexilate, hemodialysis, renal replacement therapy, hemorrhage, and atrial fibrillation was used to retrieve relevant literature. Furthermore, a manual search of the references of the identified literature was performed to capture additional data. Current evidence suggests that extracorporeal removal of dabigatran may play a role in the setting of life-threatening bleeding and emergent surgery. Conflicting evidence exists with regard to the potential for redistribution based on serum dabigatran concentrations. In addition, a number of practicalities must be considered before incorporating this technique in the clinical setting. Extracorporeal removal of dabigatran may be a treatment modality in selected patients who require emergency reversal.

A 'reluctant' critical review: 'Manual for evidence-based clinical practice (2015)'

BACKGROUND

The Users' Guides to the Medical Literature Manual has been a major influence on the teaching and practice of health care globally.

METHODS

The 3rd edition of the multi-authored Manual was reviewed using the principles outlined in Evidence-based Medicine (EBM) texts. One 'clinical scenario' was selected for critical appraisal, as were several chapters; objectivity was enhanced by citing references to support opinions. RESULTS (SUMMARY OF THE APPRAISAL): (1) Strengths: Clinical pearls, too numerous to list.

EXAMPLES

(i) evidence is never enough to drive clinical decision making; (ii) do not rush to adopt new interventions; and (iii) question efficacy data based only on surrogate markers. (2) Weaknesses: The Manual shares shortcomings of textbooks discussed by Straus et al.: (i) references may not be current, important ones may be excluded and citations may be selective; (ii) often, opinion-based; and (iii) delays between revisions. (3) Notable omissions: Little or no discussion of: (i) important segments of the population: those <18 years of age, >65 years of age and those with multimorbidity; (ii) surgical disciplines; (iii) Greenhalgh et al.'s essay on EBM; (iv) alternate views on the hierarchy of evidence; and (vi) critical thinking. (4) Additional issues: (i) Omission of important references on dabigatran (clinical scenario: chapter 13.1); (ii) authors' advice (Chapter 13.3) to 'bypass the discussion section of published research'; and (iii) the advocacy of pre-appraised sources of evidence and network meta-analysis without warnings about limitations, are critiqued.

CONCLUSION

The Manual has several clinical pearls but readers should also be aware of shortcomings.

Clinical utility of dabigatran in United Arab Emirates. A pharmacovigilance study

Objectives:

To provide early data regarding clinical utility of dabigatran in Al-Ain, United Arab Emirates (UAE).

Methods:

This was an ethics approved retrospective cross sectional study. We retrieved a total of 76 patients who were using dabigatran from September to December 2014 in the Cardiology Clinic at Al-Ain Hospital, Al-Ain, UAE. The primary analysis was designed to test the frequency of bleeding events (rate) with dabigatran 75, 110, and 150 mg.

Results:

The mean age ± standard deviation of cohort was 67.9 ± 1.5 years (range; 29-98 years), composed of males (52.6%) with mean age of 66.3 ± 1.7 years, and females (47.4%) with mean age of 69.6 ± 1.1 years. The highest age group was those between 61-80 years (60.5%). Most comprised the age strata of ≤75 years (73.7%). The main indication for dabigatran use was atrial fibrillation. The rate of bleeding with dabigatran was 18/76 (23.7%), and melena was the leading cause of bleeding 8/76 (10.7%). The hospitalization rate was 67.1%, dabigatran withdrawal rate was 0.01%, and mortality rate was 6.5%. The cohort had exhibited incidences of minor bleeding with one fatal major bleeding, high co-morbidities, admission, and readmission, which was not directly linked to dabigatran. We did not identify any relation of death due to dabigatran.

Conclusion:

Dabigatran is a suitable alternative to warfarin obviating the need for repetitive international normalized ratio monitoring, however, it may need plasma drug monitoring.

The shortcomings of clinical practice guidelines

Accumulation of medical knowledge related to diagnosis and management over the last 5-6 decades has altered the course of diseases, improved clinical outcomes and increased survival. Thus, it has become difficult for the practicing physician to evaluate the long-term effects of a particular therapy on survival of an individual patient. Further, the approach by each physician to an individual patient with the same disease is not always uniform. In an attempt to assist physicians in applying newly acquired knowledge to patients, clinical practice guidelines were introduced by various scientific societies. Guidelines assist in facilitating the translation of new research discoveries into clinical practice; however, despite the improvements over the years, there are still several issues related to guidelines that often appear ‘lost in translation'. Guidelines are based on the results of randomized clinical trials, other nonrandomized studies, and expert opinion (i.e. the opinion of most members of the guideline committees). The merits and limitations of randomized clinical trials, guideline committees, and presentation of guidelines will be discussed. In addition, proposals to improve guidelines will be presented.