Point-of-care INR measurement in children requiring warfarin: what has been evaluated and future directions

Self-testing and self-management of oral anticoagulation therapy in children

Children and adolescents on oral anticoagulation therapy (OAT) present special challenges in terms of rapid fluctuations in International Normalised Ratio (INR) values, interruption in daily life due to frequent hospital/doctor visits, and difficulties and pain in the performance of venepuncture. Optimised management of OAT improves the quality of treatment, potentially accomplished by new methods such as patient self-testing (PST) and patient self-management (PSM). A review was performed, identifying 11 trials with children and adolescents. All studies had different methodological problems, predominantly by being non-randomised trials. A total of 284 patients were included with a mean follow-up of 22 months, finding a time within therapeutic INR target range between 63% and 84%. The coagulometers used for estimating the INR values were found to have sufficient precision and accuracy for clinical use, but external quality control is probably advisable. It can be concluded that PST and PSM are at least as good treatment options as conventional management in highly selected children. Larger studies, preferably randomised, controlled trials using clinical endpoints, are obviously needed in order to elucidate whether these new regimens of treatment are superior to conventional management of oral anticoagulation therapy.

The clinical effectiveness and cost-effectiveness of point-of-care tests (CoaguChek system, INRatio2 PT/INR monitor and ProTime Microcoagulation system) for the self-monitoring of the coagulation status of people receiving long-term vitamin K antagonist therapy, compared with standard UK practice: systematic review and economic evaluation

BACKGROUND

Self-monitoring (self-testing and self-management) could be a valid option for oral anticoagulation therapy monitoring in the NHS, but current evidence on its clinical effectiveness or cost-effectiveness is limited.

OBJECTIVES

We investigated the clinical effectiveness and cost-effectiveness of point-of-care coagulometers for the self-monitoring of coagulation status in people receiving long-term vitamin K antagonist therapy, compared with standard clinic monitoring.

DATA SOURCES

We searched major electronic databases (e.g. MEDLINE, MEDLINE In Process & Other Non-Indexed Citations, EMBASE, Bioscience Information Service, Science Citation Index and Cochrane Central Register of Controlled Trials) from 2007 to May 2013. Reports published before 2007 were identified from the existing Cochrane review (major databases searched from inception to 2007). The economic model parameters were derived from the clinical effectiveness review, other relevant reviews, routine sources of cost data and clinical experts' advice.

REVIEW METHODS

We assessed randomised controlled trials (RCTs) evaluating self-monitoring in people with atrial fibrillation or heart valve disease requiring long-term anticoagulation therapy. CoaguChek(®) XS and S models (Roche Diagnostics, Basel, Switzerland), INRatio2(®) PT/INR monitor (Alere Inc., San Diego, CA USA), and ProTime Microcoagulation system(®) (International Technidyne Corporation, Nexus Dx, Edison, NJ, USA) coagulometers were compared with standard monitoring. Where possible, we combined data from included trials using standard inverse variance methods. Risk of bias assessment was performed using the Cochrane risk of bias tool. A de novo economic model was developed to assess the cost-effectiveness over a 10-year period.

RESULTS

We identified 26 RCTs (published in 45 papers) with a total of 8763 participants. CoaguChek was used in 85% of the trials. Primary analyses were based on data from 21 out of 26 trials. Only four trials were at low risk of bias. Major clinical events: self-monitoring was significantly better than standard monitoring in preventing thromboembolic events [relative risk (RR) 0.58, 95% confidence interval (CI) 0.40 to 0.84; p = 0.004]. In people with artificial heart valves (AHVs), self-monitoring almost halved the risk of thromboembolic events (RR 0.56, 95% CI 0.38 to 0.82; p = 0.003) and all-cause mortality (RR 0.54, 95% CI 0.32 to 0.92; p = 0.02). There was greater reduction in thromboembolic events and all-cause mortality through self-management but not through self-testing. Intermediate outcomes: self-testing, but not self-management, showed a modest but significantly higher percentage of time in therapeutic range, compared with standard care (weighted mean difference 4.44, 95% CI 1.71 to 7.18; p = 0.02). Patient-reported outcomes: improvements in patients' quality of life related to self-monitoring were observed in six out of nine trials. High preference rates were reported for self-monitoring (77% to 98% in four trials). Net health and social care costs over 10 years were £7295 (self-monitoring with INRatio2); £7324 (standard care monitoring); £7333 (self-monitoring with CoaguChek XS) and £8609 (self-monitoring with ProTime). The estimated quality-adjusted life-year (QALY) gain associated with self-monitoring was 0.03. Self-monitoring with INRatio2 or CoaguChek XS was found to have ≈ 80% chance of being cost-effective, compared with standard monitoring at a willingness-to-pay threshold of £20,000 per QALY gained.

CONCLUSIONS

Compared with standard monitoring, self-monitoring appears to be safe and effective, especially for people with AHVs. Self-monitoring, and in particular self-management, of anticoagulation status appeared cost-effective when pooled estimates of clinical effectiveness were applied. However, if self-monitoring does not result in significant reductions in thromboembolic events, it is unlikely to be cost-effective, based on a comparison of annual monitoring costs alone. Trials investigating the longer-term outcomes of self-management are needed, as well as direct comparisons of the various point-of-care coagulometers.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013004944.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

EMPoWARed: Edmonton pediatric warfarin self-management study

BACKGROUND

Patient self-management (PSM) in adults is safer and more cost effective than conventional management. Warfarin is a narrow therapeutic index drug with individual patient response to changes and frequently a long-term therapy. Children and their families are proposed to be able to effectively manage their child's warfarin therapy. Increased health related quality of life is highly associated with effective therapy in patients with chronic conditions.

OBJECTIVES

The aim of this study is to evaluate the safety and efficacy of PSM over time including HRQOL and variables that may influence PFU success at PSM.

PATIENTS/METHODS

Children and their family units (PFUs) current performing patient self-testing/monitoring for ≥ 3 months were enrolled in this cohort study. PFUs participated in comprehensive education on warfarin testing and management followed by an apprenticeship. Socio-demographic, clinical, and laboratory data were collected to evaluate safety and efficacy and health related quality of life. Outcomes were compared between the first 6 months on PSM (phase 1) and the last 6 months data collected on PSM (phase 2).

RESULTS

Forty-two patients performed PSM for a median of 2.7 years (range: 1.1-6.2 years). Time in therapeutic range was 90% and 92.9% (p=0.30) in phases 1 and 2 respectively. All measures were strongly associated with improved heath related quality of life. PFUs socio-demographic status did not influence success at PSM. All PFUs maintained warfarin knowledge and INR testing competency. Warfarin dosing decision errors median 0 (range: 0-5, p=0.73) and a median 0 (range 0-4, p=0.55) per patient in phases 1 and 2 respectively. There were no adverse hemorrhagic or thrombotic events.

CONCLUSIONS

Empowering PFUs to self-manage warfarin results in increased knowledge and understanding of their health condition, improved commitment to their health care and adherence to medication regimens and is demonstrated to be sustainable over time.

The economic costs of routine INR monitoring in infants and children--examining point-of-care devices used within the home setting compared to traditional anticoagulation clinic monitoring

INTRODUCTION

The use of point-of-care (POC) devices within the home for routine INR monitoring has demonstrated reliability, safety and effectiveness in the management of infants and children requiring long-term warfarin therapy. However, a comprehensive cost-analysis of using this method of management, compared to attending anticoagulation clinics has not been reported. The aim of this study was to compare the estimated societal costs of attending anticoagulation clinics for routine INR monitoring to using a POC test in the home.

MATERIALS AND METHODS

This study used a comparative before-and-after design that included 60 infants and children managed via the Haematology department at a tertiary paediatric centre. Each participant was exposed to both modes of management at various times for a period of ≥3 months. A questionnaire, consisting of 25 questions was sent to families to complete and return. Data collected included: the frequency of monitoring, mode of travel to and from clinics, total time consumed, and primary carer's income level.

RESULTS

The home monitoring cohort saved a total of 1 hour 19 minutes per INR test compared to attending anticoagulation clinics and had a cost saving to society of $66.83 (AUD) per INR test compared to traditional care; incorporating health sector costs, travel expenses and lost time.

CONCLUSIONS

The traditional model of care requires a considerable investment of time per test from both child and carer. Home INR monitoring in infants and children provides greater societal economic benefits compared to traditional models.