A multicentre randomised assessment of the DAWN AC computer-assisted oral anticoagulant dosage program

Development and validation of a mobile application based on a machine learning model to aid in predicting dosage of vitamin K antagonists among Indian patients post mechanical heart valve replacement

Patients who undergo heart valve replacements with mechanical valves need to take Vitamin K Antagonists (VKA) drugs (Warfarin, Nicoumalone) which has got a very narrow therapeutic range and needs very close monitoring using PT-INR. Accessibility to physicians to titrate drugs doses is a major problem in low-middle income countries (LMIC) like India. Our work was aimed at predicting the maintenance dosage of these drugs, using the de-identified medical data collected from patients attending an INR Clinic in South India. We used artificial intelligence (AI) - machine learning to develop the algorithm. A Support Vector Machine (SVM) regression model was built to predict the maintenance dosage of warfarin, who have stable INR values between 2.0 and 4.0. We developed a simple user friendly android mobile application for patients to use the algorithm to predict the doses. The algorithm generated drug doses in 1100 patients were compared to cardiologist prescribed doses and found to have an excellent correlation.

Fixed dose rivaroxaban can be used in extremes of bodyweight: A population pharmacokinetic analysis

BACKGROUND

Emerging safety and efficacy data for rivaroxaban suggest traditional therapy and rivaroxaban are comparable in the morbidly obese. However, real-world data that indicate pharmacokinetic (PK) parameters are comparable at the extremes of body size are lacking. The International Society of Thrombosis and Haemostasis Scientific and Standardisation Committee (ISTH SSC) suggests avoiding the use of direct oral anticoagulants (DOACs) in patients weighing >120 kg or with a body mass index >40 kg/m2 and gives no recommendation on the use of DOACs in those <50 kg.

OBJECTIVES

To generate a population PK model to understand the influence of bodyweight on rivaroxaban exposure from clinical practice data.

METHOD

Rivaroxaban plasma concentrations and patient characteristics were collated between 2013 and 2018 at King's College Hospital anticoagulation clinic. A population PK model was developed using a nonlinear mixed effects approach and then used to simulate rivaroxaban concentrations at the extremes of bodyweight.

RESULTS

A robust population PK model derived from 913 patients weighing between 39 kg and 172 kg was developed. The model included data from n = 86 >120 kg, n = 74 BMI >40 kg/m2 , and n = 30 <50 kg. A one-compartment model with between-subject variability on clearance and a proportional error model best described the data. Creatinine clearance calculated by Cockcroft-Gault, with lean bodyweight as the weight descriptor in this equation, was the most significant covariate influencing rivaroxaban exposure.

CONCLUSIONS

Our work demonstrates rivaroxaban can be used at extremes of bodyweight provided renal function is satisfactory. We recommend that the ISTH SSC revises the current guidance with respect to rivaroxaban at extremes of body size.

Patient compliance with an anticoagulation management system based on a smartphone application

We developed a novel anticoagulation management system (Anticlot Assistant) based on a smartphone application (App). This study was performed to evaluate patient compliance with Anticlot Assistant. This prospective case series study involved patients receiving warfarin therapy. The eligible patients were managed via Anticlot Assistant, and outcome data were analyzed. Thirty patients were recruited. The mean time within the therapeutic range (TTR) was 56.5% ± 26.2% and the mean patient compliance with Anticlot Assistant was 52.7% ± 40.4%. The patients in good compliance group had higher TTR (65.6 ± 25.0% vs. 40.0 ± 21.0%, P = 0.009), lower time in the extremely low range (9.4 ± 10.6% vs. 27.4 ± 13.2%, P = 0.000) and in the extremely high range (1.3 ± 2.8% vs. 14.1 ± 22.3%, P = 0.004) than those in poor compliance group. Logistic regression analysis revealed that receiving an education of > 6 years was the only independent predictor of good compliance (odds ratio 8.400, 95% confidence interval 1.274-55.394, P = 0.027). Patient compliance is critical important for good outcomes and it might increase with improvements in education and more widespread use of information technology. Although further improvement is needed, Anticlot Assistant is promising and this study offered valuable experiences for further research.

[Assessing post-hospitalization therapeutic ranges in elderly patients treated for atrial fibrillation with vitamin k antagonists]

BACKGROUND

In France, anticoagulants are among the most recommended treatments for serious accidents, particularly among the elderly.

OBJECTIVES

The purpose of this study was to evaluate the impact of practical and validated tools designed to reduce the negative effects of vitamin K antagonist (VKA) treatments by assessing patients before and after the tools were implemented.

METHODS

An exhaustive before and after multi-centric cohort study was performed in the Agen territory. The follow-up period corresponded to the six-month period post-hospitalization. The principal criterion was the time in the therapeutic range (TTR) at values of 2 to 3 according to the Rosendaal method.

RESULTS

The overall time spent in the follow-up period before and after the implementation of the tools in 65- and 74-year-old patients was 58% and 64%, respectively (P=0.584). After the treatments, the TTR in the 85- to 90-year-old patients was 71.1%. An increase was observed in the number of subjects with a TTR≥70% after the implementation of the tools according to age, particularly in the 85- to 90-year-old patients (8 vs. 41; [P=0.01]). Prescription help software revealed a tendency of improvement in TTR values from 61% to 68% (P=0.472). In addition, longer therapeutic periods corresponded to longer patient lifespans (r=0.86).

CONCLUSION

This study demonstrates the feasibility and advantages of implementing tools to improve the efficacy of VKA treatment in primary care, particularly for patients from 85 to 90 years old. The results should promote the implementation of this type of treatment method at the national level.

Effect of increased time in the therapeutic range on atrial fibrillation outcomes within a centralized anticoagulation service

BACKGROUND

Clinical pharmacy anticoagulation services have improved the quality of anticoagulant therapy and are associated with lower rates of bleeding and thromboembolism compared to usual care. Several studies have found that higher time-in-therapeutic range (TTR) during warfarin therapy is associated with better warfarin outcomes. However, whether increasing TTR over time within an established anticoagulation service is associated with further reduction in bleeding and thromboembolic outcomes is unknown.

METHODS

This was a retrospective cohort study of patients with atrial fibrillation conducted at an integrated healthcare delivery system with a centralized, pharmacist-managed anticoagulation service. Clinical outcomes (clinically-relevant bleeding, ischemic stroke or systemic embolism, and all-cause mortality) and TTR were compared between two distinct time periods: 1/1/2006 through 12/31/2007 (control group) and 1/1/2012 through 12/31/2013 (observation group) with regression modeling to adjustment for potential confounders.

RESULTS

There were 3641 and 4764 patients in the control and observation groups, respectively. The mean age was 74.3 years and 54.4% of the cohort was female. Mean TTR was higher in the observation group (70.5% vs. 63.4%, p < 0.001). The composite outcome of clinically-relevant bleeding, thromboembolism and all-cause mortality occurred in 4.6% and 3.6% of the control and observation groups, respectively (adjusted odds ratio = 0.69; 95% confidence interval 0.54-0.87). Individual rates of stroke/systemic embolism and all-cause mortality were each lower in the observation group (both p < 0.05) while clinically-relevant bleeding was not significantly different (p = 0.256).

CONCLUSION

Increased TTR within a clinical pharmacy anticoagulation management service was associated with a lower risk of the composite outcomes of bleeding, thromboembolism and death in a large atrial fibrillation population receiving warfarin.

Randomised comparison of a simple warfarin dosing algorithm versus a computerised anticoagulation management system for control of warfarin maintenance therapy

Excellent control of the international normalised ratio (INR) is associated with improved clinical outcomes in patients receiving warfarin, and can be achieved by anticoagulation clinics but is difficult in general practice. Anticoagulation clinics have often used validated commercial computer systems to manage the INR, but these are not usually available to general practitioners. It was the objective of this study to perform a randomised trial of a simple one-step warfarin dosing algorithm against a widely used computerised dosing system. During the period of introduction of a commercial computerised warfarin dosing system (DAWN AC) to an anticoagulation clinic, patients were randomised to have warfarin dose adjustment done according to recommendations of the existing warfarin dosing algorithm or to those of the computerised system. The study tested if the computerised system was non-inferior to the existing algorithm for the primary outcome of time in therapeutic INR range of 2.0–3.0 (TTR), with a one-sided non-inferiority margin of 4.5%. There were 541 patients randomised to commercial computerised system and 527 to the algorithm. Median follow-up was 159 days. A dose recommendation was provided and followed in 91% of occasions for the computerised system and in 90% for the algorithm (p=0.03). The mean TTR was 71.0% (standard deviation [SD] 23.2) for the computerised system and 71.9% (SD 22.9) for the algorithm (difference 0.9% [95% confidence interval: –1.4% to 4.1%];p-value for noninferiority=0.002;p-value for superiority=0.34). In conclusion, similar maintenance control of the INR was achieved with a simple one-step dosing algorithm and a commercial computerised management system.

The Marginal Costs of Adverse Drug Events Associated With Exposures to Anticoagulants and Hypoglycemic Agents During Hospitalization

BACKGROUND

Anticoagulants and hypoglycemic agents are 2 of the most challenging drug classes for medical management in the hospital resulting in many adverse drug events (ADEs).

OBJECTIVE

Estimating the marginal cost (MC) of ADEs associated with anticoagulants and hypoglycemic agents for adults in 5 patient groups during their hospital stay and the total annual ADE costs for all patients exposed to these drugs during their stay.

RESEARCH DESIGN AND SUBJECT

Data are from 2010 to 2013 Healthcare Cost and Utilization Project (HCUP) State Inpatient Databases and Medicare Patient Safety Monitoring System (MPSMS). Deidentified patients were linked using probabilistic matching in the same hospital and year for 5 patient groups. ADE information was obtained from the MPSMS using retrospective structured record review. Costs were derived using HCUP cost-to-charge ratios. MC estimates were made using Extended Estimating Equations controlling for patient characteristics, comorbidities, hospital procedures, and hospital characteristics. MC estimates were applied to the 2013 HCUP National Inpatient Sample to estimate annual ADE costs.

RESULTS

Adjusted MC estimates were smaller than unadjusted measures with most groups showing estimates that were at least 50% less. Adjusted anticoagulant ADE costs added >45% and Hypoglycemic ADE costs added >20% to inpatient costs. The 2013 hospital cost estimates for ADEs associated with anticoagulants and hypoglycemic agents were >$2.5 billion for each drug class.

CONCLUSIONS

This study demonstrates the importance of accounting for confounders in the estimation of ADEs, and the importance of separate estimates of ADE costs by drug class.

Features of electronic health records necessary for the delivery of optimized anticoagulant therapy: consensus of the EHR Task Force of the New York State Anticoagulation Coalition

BACKGROUND

Oral anticoagulants are prescribed to millions of Americans, and consequently are among the medications most likely to contribute to emergency department visits and hospitalizations. Although guidelines and consensus statements promote systematic approaches to therapy, anticoagulation (AC) management is often suboptimal. Electronic health records (EHRs) have the potential to improve safety and quality but have not yet incorporated specialized features necessary to optimize therapy.

OBJECTIVE

To generate a comprehensive, consensus-based list of EHR features clinically necessary to deliver optimized AC management, provide a "language bridge" to accelerate incorporation of features into EHR systems, and suggest mechanisms for the objective evaluation of available EHRs.

METHODS

A multidisciplinary panel of AC specialists utilized the framework of a previously published consensus statement to map outpatient AC management and developed a comprehensive array of sequential computer logic steps using a restricted language scheme. Logic steps were then translated into narrative descriptions of potential EHR features, which were refined through multiple group evaluations. A finalized list of proposed features was ranked according to perceived clinical necessity by physician, pharmacist, and nurse panelists in a blinded manner using a 5-point Likert scale. Features receiving no more than 1 dissenting opinion were included in a finalized list of clinically necessary features.

RESULTS

The task force generated 78 recommended EHR features across 20 key discrete areas and 425 individual logic steps. All recommended features received Strongly Agree or Agree rankings regarding their perceived clinical necessity, and no feature received more than a single Disagree response.

CONCLUSION

The incorporation of key AC-related features into existing EHRs or specialized AC management systems has the potential to systematize the delivery of optimal AC care by health care professionals at the point of care. Optimized AC management has the potential to reduce adverse drug events associated with anticoagulant therapy in the outpatient setting.

[Computer aided dosage management of phenprocoumon anticoagulation therapy. Clinical validation]

A recently developed multiparameter computer-aided expert system (TheMa) for guiding anticoagulation with phenprocoumon (PPC) was validated by a prospective investigation in 22 patients. The PPC-INR-response curve resulting from physician guided dosage was compared to INR values calculated by "twin calculation" from TheMa recommended dosage. Additionally, TheMa was used to predict the optimal time to perform surgery or invasive procedures after interruption of anticogulation therapy.

RESULTS

Comparison of physician and TheMa guided anticoagulation showed almost identical accuracy by three quantitative measures: Polygon integration method (area around INR target) 616.17 vs. 607.86, INR hits in the target range 166 vs. 161, and TTR (time in therapeutic range) 63.91 vs. 62.40 %. After discontinuation of anticoagulation therapy, calculating the INR phase-out curve with TheMa INR prognosis of 1.8 was possible with a standard deviation of 0.50 ± 0.59 days.

CONCLUSION

Guiding anticoagulation with TheMa was as accurate as Physician guided therapy. After interruption of anticoagulant therapy, TheMa may be used for calculating the optimal time performing operations or initiating bridging therapy.

Risks to patient safety associated with implementation of electronic applications for medication management in ambulatory care--a systematic review

BACKGROUND

The objective was to find evidence to substantiate assertions that electronic applications for medication management in ambulatory care (electronic prescribing, clinical decision support (CDSS), electronic health record, and computer generated paper prescriptions), while intended to reduce prescribing errors, can themselves result in errors that might harm patients or increase risks to patient safety.

METHODS

Because a scoping search for adverse events in randomized controlled trials (RCTs) yielded few relevant results, we systematically searched nine databases, including MEDLINE, EMBASE, and The Cochrane Database of Systematic Reviews for systematic reviews and studies of a wide variety of designs that reported on implementation of the interventions. Studies that had safety and adverse events as outcomes, monitored for them, reported anecdotally adverse events or other events that might indicate a threat to patient safety were included.

RESULTS

We found no systematic reviews that examined adverse events or patient harm caused by organizational interventions. Of the 4056 titles and abstracts screened, 176 full-text articles were assessed for inclusion. Sixty-one studies with appropriate interventions, settings and participants but without patient safety, adverse event outcomes or monitoring for risks were excluded, along with 77 other non-eligible studies. Eighteen randomized controlled trials (RCTs), 5 non-randomized controlled trials (non-R,CTs) and 15 observational studies were included. The most common electronic intervention studied was CDSS and the most frequent clinical area was cardio-vascular, including anti-coagulants. No RCTS or non-R,CTS reported adverse event. Adverse events reported in observational studies occurred less frequently after implementation of CDSS. One RCT and one observational study reported an increase in problematic prescriptions with electronic prescribing

CONCLUSIONS

The safety implications of electronic medication management in ambulatory care have not been established with results from studies included in this systematic review. Only a minority of studies that investigated these interventions included threats to patients' safety as outcomes or monitored for adverse events. It is therefore not surprising that we found little evidence to substantiate fears of new risks to patient safety with their implementation. More research is needed to focus on the draw-backs and negative outcomes that implementation of these interventions might introduce.

Computerized advice on drug dosage to improve prescribing practice

BACKGROUND

Maintaining therapeutic concentrations of drugs with a narrow therapeutic window is a complex task. Several computer systems have been designed to help doctors determine optimum drug dosage. Significant improvements in health care could be achieved if computer advice improved health outcomes and could be implemented in routine practice in a cost-effective fashion. This is an updated version of an earlier Cochrane systematic review, first published in 2001 and updated in 2008.

OBJECTIVES

To assess whether computerized advice on drug dosage has beneficial effects on patient outcomes compared with routine care (empiric dosing without computer assistance).

SEARCH METHODS

The following databases were searched from 1996 to January 2012: EPOC Group Specialized Register, Reference Manager; Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Ovid; EMBASE, Ovid; and CINAHL, EbscoHost. A "top up" search was conducted for the period January 2012 to January 2013; these results were screened by the authors and potentially relevant studies are listed in Studies Awaiting Classification. The review authors also searched reference lists of relevant studies and related reviews.

SELECTION CRITERIA

We included randomized controlled trials, non-randomized controlled trials, controlled before-and-after studies and interrupted time series analyses of computerized advice on drug dosage. The participants were healthcare professionals responsible for patient care. The outcomes were any objectively measured change in the health of patients resulting from computerized advice (such as therapeutic drug control, clinical improvement, adverse reactions).

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed study quality. We grouped the results from the included studies by drug used and the effect aimed at for aminoglycoside antibiotics, amitriptyline, anaesthetics, insulin, anticoagulants, ovarian stimulation, anti-rejection drugs and theophylline. We combined the effect sizes to give an overall effect for each subgroup of studies, using a random-effects model. We further grouped studies by type of outcome when appropriate (i.e. no evidence of heterogeneity).

MAIN RESULTS

Forty-six comparisons (from 42 trials) were included (as compared with 26 comparisons in the last update) including a wide range of drugs in inpatient and outpatient settings. All were randomized controlled trials except two studies. Interventions usually targeted doctors, although some studies attempted to influence prescriptions by pharmacists and nurses. Drugs evaluated were anticoagulants, insulin, aminoglycoside antibiotics, theophylline, anti-rejection drugs, anaesthetic agents, antidepressants and gonadotropins. Although all studies used reliable outcome measures, their quality was generally low.This update found similar results to the previous update and managed to identify specific therapeutic areas where the computerized advice on drug dosage was beneficial compared with routine care:1. it increased target peak serum concentrations (standardized mean difference (SMD) 0.79, 95% CI 0.46 to 1.13) and the proportion of people with plasma drug concentrations within the therapeutic range after two days (pooled risk ratio (RR) 4.44, 95% CI 1.94 to 10.13) for aminoglycoside antibiotics;2. it led to a physiological parameter more often within the desired range for oral anticoagulants (SMD for percentage of time spent in target international normalized ratio +0.19, 95% CI 0.06 to 0.33) and insulin (SMD for percentage of time in target glucose range: +1.27, 95% CI 0.56 to 1.98);3. it decreased the time to achieve stabilization for oral anticoagulants (SMD -0.56, 95% CI -1.07 to -0.04);4. it decreased the thromboembolism events (rate ratio 0.68, 95% CI 0.49 to 0.94) and tended to decrease bleeding events for anticoagulants although the difference was not significant (rate ratio 0.81, 95% CI 0.60 to 1.08). It tended to decrease unwanted effects for aminoglycoside antibiotics (nephrotoxicity: RR 0.67, 95% CI 0.42 to 1.06) and anti-rejection drugs (cytomegalovirus infections: RR 0.90, 95% CI 0.58 to 1.40);5. it tended to reduce the length of time spent in the hospital although the difference was not significant (SMD -0.15, 95% CI -0.33 to 0.02) and to achieve comparable or better cost-effectiveness ratios than usual care;6. there was no evidence of differences in mortality or other clinical adverse events for insulin (hypoglycaemia), anaesthetic agents, anti-rejection drugs and antidepressants.For all outcomes, statistical heterogeneity quantified by I(2) statistics was moderate to high.

AUTHORS' CONCLUSIONS

This review update suggests that computerized advice for drug dosage has some benefits: it increases the serum concentrations for aminoglycoside antibiotics and improves the proportion of people for which the plasma drug is within the therapeutic range for aminoglycoside antibiotics.It leads to a physiological parameter more often within the desired range for oral anticoagulants and insulin. It decreases the time to achieve stabilization for oral anticoagulants. It tends to decrease unwanted effects for aminoglycoside antibiotics and anti-rejection drugs, and it significantly decreases thromboembolism events for anticoagulants. It tends to reduce the length of hospital stay compared with routine care while comparable or better cost-effectiveness ratios were achieved.However, there was no evidence that decision support had an effect on mortality or other clinical adverse events for insulin (hypoglycaemia), anaesthetic agents, anti-rejection drugs and antidepressants. In addition, there was no evidence to suggest that some decision support technical features (such as its integration into a computer physician order entry system) or aspects of organization of care (such as the setting) could optimize the effect of computerized advice.Taking into account the high risk of bias of, and high heterogeneity between, studies, these results must be interpreted with caution.

The clinical evaluation of International Normalized Ratio variability and control in conventional oral anticoagulant administration by use of the variance growth rate

INTRODUCTION

The time in target International Normalized Ratio (INR) range (TIR) is used to assess the control and intensity of oral anticoagulation, but it does not measure variation in the INR.

OBJECTIVES

The value of assessing INR variability by use of the variance growth rate (VGR) as a predictor of events was investigated in patients treated with warfarin.

METHODS

Three different methods of VGR determination (A, B1, and B2) together with the TIR were studied. Method A measures both INR variability and control, but methods B1 and B2 measure variability only. The VGR and TIR were determined over three time periods: overall follow-up to an event, and 6 months and 3 months before an event.

RESULTS

Six hundred and sixty-one control patients were matched to 158 cases (bleeding, thromboembolism, or death). With all VGR methods, the risk of an event was greater in unstable patients at 6 months before an event than in stable patients. Method A demonstrated the greatest risk 3 months before an event in the unstable VGR group as compared with the stable group (odds ratio 3.3, 95% confidence interval 1.9-5.7, P < 0.005). The risk of an event was 1.9 times greater in patients with a low TIR (< 39%) than in those with a high TIR (> 80%) in the 3-month period (P = 0.02). Risk of bleeding was significantly greater in the 3-month period in patients with unstable VGR, with the greatest risk found with method B2 (P < 0.01).

CONCLUSIONS

Patients with unstable anticoagulation have a significantly increased risk of 'clinical events' at 3 and 6 months before an event. The VGR can be incorporated into computer-dosage programs, and may offer additional safety when oral anticoagulation is monitored.

Safety and usability evaluation of a web-based insulin self-titration system for patients with type 2 diabetes mellitus

OBJECTIVE

The rising incidence of type 2 diabetes mellitus (T2DM) induces severe challenges for the health care system. Our research group developed a web-based system named PANDIT that provides T2DM patients with insulin dosing advice using state of the art clinical decision support technology. The PANDIT interface resembles a glucose diary and provides advice through pop-up messages. Diabetes nurses (DNs) also have access to the system, allowing them to intervene when needed. The objective of this study was to establish whether T2DM patients can safely use PANDIT at home. To this end, we assessed whether patients experience usability problems with a high risk of compromising patient safety when interacting with the system, and whether PANDIT's insulin dosing advice are clinically safe.

RESEARCH DESIGN AND METHODS

The study population consisted of patients with T2DM (aged 18-80) who used a once daily basal insulin as well as DNs from a university hospital. The usability evaluation consisted of think-aloud sessions with four patients and three DNs. Video data, audio data and verbal utterances were analyzed for usability problems encountered during PANDIT interactions. Usability problems were rated by a physician and a usability expert according to their potential impact on patient safety. The usability evaluation was followed by an implementation with a duration of four weeks. This implementation took place at the patients' homes with ten patients to evaluate clinical safety of PANDIT advice. PANDIT advice were systematically compared with DN advice. Deviating advice were evaluated with respect to patient safety by a panel of experienced physicians, which specialized in diabetes care.

RESULTS

We detected seventeen unique usability problems, none of which was judged to have a high risk of compromising patient safety. Most usability problems concerned the lay-out of the diary, which did not clearly indicate which data entry fields had to be entered in order to obtain an advice. 27 out of 74 (36.5%) PANDIT advice differed from those provided by DNs. However, only one of these (1.4%) was considered unsafe by the panel.

CONCLUSION

T2DM patients with no prior experience with the web-based self-management system were capable of consulting the system without encountering significant usability problems. Furthermore, the large majority of PANDIT advice were considered clinically safe according to the expert panel. One advice was considered unsafe. This could however easily be corrected by implementing a small modification to the system's knowledge base.

Antithrombotic therapy in patients with heart valve prostheses

Heart valve prostheses carry a risk for thrombosis and require an antithrombotic strategy to prevent stroke, systemic embolism, and prosthetic valve thrombosis. Contemporary randomized trials to guide the clinician on the optimal anticoagulant treatment are scarce, and the validity of the historical data for current recommendations can be questioned in view of the changes in valve prostheses, the patient population, and antithrombotic therapies. This limited evidence from clinical trials translates into divergent recommendations from the different scientific societies on the optimal intensity of oral anticoagulation and on the indication for antiplatelet therapy. The availability of new antithrombotic agents and the unclear thrombotic risk of the currently used prostheses underscore the need to redefine antithrombotic treatment in patients with heart valve prostheses.

Economic evaluation of the use of point-of-care devices in patients with long term oral anticoagulation

To examine the cost and cost-effectiveness of the use of point-of-care (POC) devices by the general practitioner (GP), in anticoagulation clinic or by the patient in self-testing (PST) and self-management (PSM), compared with standard laboratory testing to realize international normalized ratio tests for patients on long term anticoagulation therapy. An economic evaluation was performed from the Belgian health care payer's perspective using a Markov model. Outcomes data were derived from a meta-analysis and cost data were derived from claims databases. Several scenarios were tested based on number of tests and GP's contacts and probabilistic sensitivity analysis was used to handle uncertainty. Evidence on the impact of POC on mortality was only found for PSM. Therefore, a cost-effectiveness analysis was performed for PSM and for other strategies, only a cost comparison was done. With an unchanged number of tests, POC is cost-saving compared to laboratory testing (probability > 70%). In scenarios where POC induces more tests, results were different: with 52 tests/year, only PSM kept a probability of remaining cost-saving superior to 50%. Except in the case of 100% of GP consultations maintained and 52 tests/year performed, PSM resulted in significantly more "life years gained" (LYG) than usual care and was on average cost-saving. The organisation of long term oral anticoagulation monitoring should be directed towards PSM and, to a lesser extent, PST for selected and trained patients.

Clinical validation of a new algorithm for computerized dosing of vitamin K antagonist therapy: a retrospective simulation study

The number of patients on oral anticoagulant therapy has increased in recent years, and this trend is expected to continue. The increased workload for physicians has led to the development of computerized systems to make organizational workflow more efficient. These programs may include algorithms to propose a weekly dosage and timing for the following visit. Before introducing a new algorithm in clinical practice, its safety and efficacy must be validated. We undertook a retrospective simulation study to test a new algorithm for the TAOnet system. The main outcome was the percentage of concordant and discordant proposals between manual- and algorithm-based prescriptions. Pairs of computerized and physician prescriptions were assessed. They were categorized as 0.1-5, 5.1-10 and >10% if the dose was different, and assigned as "algorithm better" or "manual better" dependent upon the subsequent international normalized ratio value. In 61.0% of cases, the manual and computerized weekly dosage assignments were identical; in 15.3% of cases, the difference was between 0.1 and 5%; in 14.7 of cases, it was between 5.1 and 10%; and in 9.0% of cases, it was >10%. The algorithm did better in 43.9% of discordant pairs, generally due to less frequent under-dosing. In conclusion, the new algorithm proved to consistently overlap with the manual method. The algorithm is useful but must be tested in a multi-center, prospective, interventional study.

Coagulometer international sensitivity index (ISI) derivation, a rapid method using the prothrombin time/international normalized ratio (PT/INR) Line: a multicenter study

BACKGROUND

The original WHO procedure for prothrombin time (PT) standardization has been almost entirely abandoned because of the universal use of PT coagulometers. These often give different international normalized ratio (INR) results from the manual method, between individual makes of instruments and with instruments from the same manufacture.

METHOD

A simple procedure is required to derive local INR with coagulometers. The PT/INR Line method has recently been developed using five European Concerted Action on Anticoagulation (ECAA) certified plasmas to derive local INR. This procedure has been modified to derive a coagulometer PT/INR Line providing International Sensitivity Index (ISI) and mean normal PT (MNPT) for coagulometers and give local INR. Results have been compared with conventional ISI calibrations at the same laboratories.

RESULTS

With human thromboplastins, mean ISI by local calibration was 0.93 (range: 0.77-1.16). With the PT/INR Line, mean coagulometer ISI was higher, for example 0.99 (0.84-1.23) but using the PT/INR Line derived MNPT there was no difference in local INR. Between-centre INR variation of a certified validation plasma was reduced with human and bovine reagents after correction with local ISI calibrations and the PT/INR Line.

CONCLUSION

The PT/INR Line-ISI with its derived MNPT is shown to provide reliable local INR with the 13 different reagent/coagulometer combinations at the 28 centres in this international study.

Management of warfarin in children with heart disease

Warfarin is an important therapy for children with heart disease. We assessed the impact of a computerized warfarin-dosing software program on measured INR values using a historical case-control design. Children (infant to 20 years of age) with cardiac disease managed with warfarin between September 1, 2006, and August 31, 2009 were included in the analysis. Warfarin therapy was tailored to specific underlying conditions based on consensus guidelines. Before the use of dosing software, medication adjustments were made by physicians using published guidelines. After software implementation, dosing adjustments were based on the software algorithm. There were 86 subjects in this analysis, and the most common indication for warfarin was prosthetic valve. Overall, the incidence of adverse bleeding events was 1.3% per patient-year. An analysis of patient-related factors associated with a low percentage of time within goal range demonstrated that both female sex (P = 0.048) and nonwhite race (P = 0.037) were significantly associated with less time in the target range. Use of the software program was associated with an increase in the percentage of time during which the INR was within the target range from 41.4 to 53.1% (P < 0.001). Incorporation of a computerized software program to assist dosing can improve the percentage of time that children with cardiac disease requiring warfarin remain within the target therapeutic range. Strategies to improve management and decrease sex and racial disparities in this population are needed.

Computerized clinical decision support systems for therapeutic drug monitoring and dosing: a decision-maker-researcher partnership systematic review

Background

Some drugs have a narrow therapeutic range and require monitoring and dose adjustments to optimize their efficacy and safety. Computerized clinical decision support systems (CCDSSs) may improve the net benefit of these drugs. The objective of this review was to determine if CCDSSs improve processes of care or patient outcomes for therapeutic drug monitoring and dosing.

Methods

We conducted a decision-maker-researcher partnership systematic review. Studies from our previous review were included, and new studies were sought until January 2010 in MEDLINE, EMBASE, Evidence-Based Medicine Reviews, and Inspec databases. Randomized controlled trials assessing the effect of a CCDSS on process of care or patient outcomes were selected by pairs of independent reviewers. A study was considered to have a positive effect (i.e., CCDSS showed improvement) if at least 50% of the relevant study outcomes were statistically significantly positive.

Results

Thirty-three randomized controlled trials were identified, assessing the effect of a CCDSS on management of vitamin K antagonists (14), insulin (6), theophylline/aminophylline (4), aminoglycosides (3), digoxin (2), lidocaine (1), or as part of a multifaceted approach (3). Cluster randomization was rarely used (18%) and CCDSSs were usually stand-alone systems (76%) primarily used by physicians (85%). Overall, 18 of 30 studies (60%) showed an improvement in the process of care and 4 of 19 (21%) an improvement in patient outcomes. All evaluable studies assessing insulin dosing for glycaemic control showed an improvement. In meta-analysis, CCDSSs for vitamin K antagonist dosing significantly improved time in therapeutic range.

Conclusions

CCDSSs have potential for improving process of care for therapeutic drug monitoring and dosing, specifically insulin and vitamin K antagonist dosing. However, studies were small and generally of modest quality, and effects on patient outcomes were uncertain, with no convincing benefit in the largest studies. At present, no firm recommendation for specific systems can be given. More potent CCDSSs need to be developed and should be evaluated by independent researchers using cluster randomization and primarily assess patient outcomes related to drug efficacy and safety.

Transforming oral anticoagulation by combining international normalized ratio (INR) self testing and online automated management

Because of the number and complexity of issues addressed, this manuscript is divided into two major sections. The first section focuses on how new technology can transform vitamin K antagonist therapy. Specifically, evidence suggest that combining INR self testing with online automated management (STOAM) can greatly reduce the time, expense, and hassle of managing VKA therapy; improve the quality of INR control to a degree that, in large studies, has been associated with a 50% or more reduction in major events (such as stroke, myocardial infarction, major hemorrhage, and death); reduce health care costs by an estimated $4 million per 1,000 patients per year; and improve quality of life and patient satisfaction. Such improved VKA therapy should be safer, more effective, and more cost-effective than the new oral anticoagulants. The improved efficiency and outcomes also should prompt reconsideration of indications in which VKA therapy may not be the current standard of care. Although new reimbursement models are clearly needed for STOAM, the current Medicare reimbursement model for patient self testing can be utilized to make VKA management financially viable and sustainable. The second section of this article focuses on additional considerations that may be important in optimizing VKA therapy and/or selecting an online management system. A brief review is provided to examine why a recent meta analysis and a large randomized trial of self testing did not find the same degree of improvement as reported in the four STOAM trials described in the first section of this article.

Evaluation of European Concerted Action on Anticoagulation lyophilized plasmas for INR derivation using the PT/INR line

The prothrombin time/international normalized ratio (PT/INR) Line method based on 5 certified European Concerted Action on Anticoagulation (ECAA) plasmas provides reliable local INR values without conventional World Health Organization international sensitivity index calibrations. The present study investigated the use of different numbers and types of ECAA calibrant plasmas to derive accurate PT/INR Lines and reliable INR values. The numbers ranged from 3 to 10 plasmas in a set with normal or abnormal samples. Sets were selected, and sampling was repeated 1,000 times for each center to derive PT/INR Lines. The lines were selected randomly or from clusters. The INR values of 5 independent "validation" plasmas were compared before and after correction. In 56 calibrations, 5 ECAA plasmas gave better results than did fewer plasmas. Plasmas with wide-ranging INR values gave better results than randomly selected sets, and including a normal plasma was not essential. The INR deviations of validation plasmas from certified values were reduced with sets of human, bovine/combined, and rabbit reagents. Deviations of more than 10% from certified INR values were significantly reduced (P < .001).

Optimizing use of current anticoagulants

Although warfarin has been the mainstay of oral anticoagulation therapy for decades, evidence-based methods for improving the quality of warfarin therapy remain underused. The arrival of new anticoagulants that do not require routine laboratory monitoring and lack the significant dietary and drug interaction potential that are seen with warfarin is an important evolutionary step in the management of thromboembolic disease. However, it will be years before the efficacy and long-term safety of these new agents are defined. Newer oral anticoagulants will be more expensive than generic warfarin. This article examines various approaches to optimize the clinical use of warfarin. For patients able to achieve stable anticoagulation control, warfarin remains an important therapeutic option, delivering similar clinical outcomes at a fraction of the cost to the health care system.

[Stereophotography of the ocular fundus. 2. Observation method]

Traditional anticoagulant agents such as vitamin K antagonists (VKAs), unfractionated heparin (UFH), low molecular weight heparins (LMWHs) and fondaparinux have been widely used in the prevention and treatment of thromboembolic diseases. However, these agents are associated with limitations, such as the need for regular coagulation monitoring (VKAs and UFH) or a parenteral route of administration (UFH, LMWHs and fondaparinux).

Several non-VKA oral anticoagulants (NOACs) are now widely used in the prevention and treatment of thromboembolic diseases and in stroke prevention in non-valvular atrial fibrillation. Unlike VKAs, NOACs exhibit predictable pharmacokinetics and pharmacodynamics. They are therefore usually given at fixed doses without routine coagulation monitoring. However, in certain patient populations or special clinical circumstances, measurement of drug exposure may be useful, such as in suspected overdose, in patients experiencing a hemorrhagic or thromboembolic event during the treatment’s period, in those with acute renal failure, in patients who require urgent surgery or in case of an invasive procedure. This article aims at providing guidance on laboratory testing of classic anticoagulants and NOACs.