Development of a home international normalized ratio monitoring program: Strategic approach and evaluation


  • Sophie Jones,

    1. Clinical Haematology Department, Royal Children's Hospital, Melbourne, Victoria, Australia
    2. Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
    3. Department of Nursing, The University of Melbourne, Melbourne, Victoria, Australia
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  • Fiona Newall

    Corresponding author
    1. Nursing Research Department, Royal Children's Hospital, Melbourne, Victoria, Australia
    2. Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
    3. Department of Nursing, The University of Melbourne, Melbourne, Victoria, Australia
    4. Haematology Research Group, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia
    • Clinical Haematology Department, Royal Children's Hospital, Melbourne, Victoria, Australia
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  • Conflict of interest: The authors have no conflict of interest to declare.

Correspondence: Professor Fiona Newall, Clinical Haematology Department, Royal Children's Hospital, Flemington Rd, Parkville, Vic. 3052, Australia. Fax: +61 3 9349 1819; email:


The increased prevalence of thromboembolic diseases in childhood has contributed to significant expansion in services aimed at managing anticoagulant therapies in paediatrics.[1-6] Oral vitamin K antagonists (VKA) remain the anticoagulants of choice for long-term anticoagulant therapy in children despite the challenges they present regarding variable dose-response, impact of confounding factors and need for regular blood monitoring.[7-13] Strategies to minimise and manage the impact of these confounders upon stability of anticoagulant therapy in children have been explored. Anticoagulant clinics, point-of-care international normalized ratio (INR) monitoring and home INR testing programs have all been reported in the literature to afford paediatric patients and their families safe and effective management of VKA therapy.[4, 6, 9-11, 13-20]

In reviewing studies investigating the clinical outcomes of point-of-care INR monitoring and home INR testing programs, it is important to recognise that all paediatric home INR monitoring programs reported have been conducted within dedicated paediatric anticoagulant clinics.[14, 19, 21] This may limit the generalisability of the reported outcomes. This paper presents a program development pathway for establishment of a home INR monitoring service. The process used in developing this program demonstrates rigour and an emphasis on evaluation across the continuum of program development and patient outcome evaluation.[22]

Highlighted within this paper are the sequential and evidence-based processes employed to develop a dedicated paediatric home INR monitoring program that is now in its ninth year of existence. These processes include

  • Development and validation of infrastructure
  • Establishing the scope of the program
  • Education and training
  • Assessment of competency
  • Outcome evaluation
  • Funding considerations

Development and Validation of Infrastructure

Validation of the point-of-care system chosen to facilitate home INR monitoring is the essential first step to developing a service. The process of developmental haemostasis, whereby the components of the haemostatic system change quantitatively and qualitatively with age throughout childhood, means extrapolation of adult validation studies to paediatric practice is likely suboptimal.[23-26] This validation process may need to be repeated whenever point-of-care monitors distributed by commercial companies are upgraded or replaced. As such, in the time-course of the Royal Children's Hospital home INR monitoring program, two point-of-care INR monitors have been validated. The first study determined that the CoaguChek S monitor (Roche Diagnostics, Castle Hill, NSW, Australia) had an acceptable level of agreement (r = 0.885) compared with the laboratory-based venous INR.[17] Prior to upgrading to the CoaguChek XS system (released in 2006) (Roche Diagnostics) a similar validation study was undertaken. This follow-up study compared INR results generated by the CoaguChek XS with a venous INR (r = 0.81), and in addition compared both of these INR results to an INR generated using the World Health Organization reference thromboplastin (r = 0.95 and 0.9, respectively).[16]

Within the literature, numerous models of anticoagulant therapy management exist, including management by medical staff, pharmacists or nursing. Within the Royal Children's Hospital, a nurse-led Anticoagulant Clinic was developed in 1999 and has formed the foundation for all future patient care interventions.[12] Regardless of which model of care is employed within a centre planning to develop a home INR monitoring program, it is helpful that baseline safety and efficacy outcomes of anticoagulant management have been determined prior to introducing a new model of care.[12] This enables future evaluation of the clinical outcomes of the home INR monitoring program against baseline outcomes achieved by the service. Similarly, consideration needs to be given to the process of data management and any information technology infrastructure required to ensure accurate recording of patient management. The Royal Children's Hospital developed a Microsoft Access database that facilitates reporting of all management decisions associated with a child's warfarin therapy.

Finally, successful implementation of a home INR monitoring program can be achieved through the development of a clearly articulated strategic plan incorporating all elements of the training, maintenance and evaluation processes involved.[21] A strategic approach to program development aims to ensure that all requisite elements for a program's success have been considered and accommodated.

Establishing the Scope of the Program

Determining clear eligibility criteria for participation in the home INR monitoring program facilitates clear communication to multidisciplinary colleagues and families regarding entry into the program. The availability of infrastructure, staffing and training times to support families undertaking home INR monitoring will impact upon the size and scope of the program. Within the Royal Children's Hospital, the following eligibility criteria have been created:

  • Residing within the state of Victoria
  • Patient will require warfarin for at least 12 months
  • Patient and/or family have a sufficient level of English language competency to enable reading and understanding of educational material and telephone communication
  • Patient has been taking warfarin for a minimum of 3 months

These criteria have been stipulated within our institutional home INR monitoring policy document.

Additionally, all families seeking entry into the home INR monitoring program are clearly informed regarding departmental expectations of participation in this program. Information regarding these expectations is communicated verbally and reiterated within the home INR monitoring policy and procedure manual provided to all participants. In summary, families are to

  • Perform an INR test at home when instructed
  • Report all INR test results obtained at home to the Clinical Haematology Department and follow the subsequent dosing instructions
  • Attend an outpatient review of anticoagulant management annually

The annual outpatient review facilitated review of ongoing educational needs, monitoring for adverse events including bone mineral density assessment[27] and evaluation of the efficacy of anticoagulant therapy. The coordination of patients' transition to adult haematology services is vital to the ongoing operation of a home INR program. When adolescent patients are transitioned in a timely and efficient manner, the resources these patients required can be utilised for new patients commencing long-term VKA therapy.

Education and Training

The development of educational programs regarding warfarin therapy have historically lacked robust structure and evaluation.[28] A novel approach to the development of warfarin education processes was initiated at the Royal Children's Hospital when assessment of parent understanding of warfarin following delivery of usual education revealed serious shortcomings in parent understanding.[29] This baseline assessment facilitated identification of key areas in which education needed to improve and also highlighted the need for a more structured approach to education. The resultant education program was initiated as the foundation to the inaugural intake of families into the home INR monitoring program.[29] Theoretical education and practical training were both incorporated into this model of education, which afforded increased rigour and evaluation opportunities to the program.[21]

Outcome Evaluation

A multifactorial plan for evaluation of home INR monitoring outcomes needs to be established prior to commencement. This plan should incorporate assessment of participant knowledge, practical performance of an INR test, correlation of paired home INR results with a laboratory-based INR (that is, clinical agreement), target therapeutic range achievement, adverse event rates and quality of life.[21, 30] Evaluation of the Royal Children's Hospital home INR monitoring program demonstrated that the robust education and training model underpinning the program produced acceptable outcomes across all of these domains:[21]

  • Families demonstrated a significant improvement in their level of understanding regarding warfarin therapy
  • All families participating in the program were able to successfully perform an INR test at the conclusion of the training day
  • Correlation between home and laboratory-based INR monitoring was strong (r = 0.949), demonstrating acceptable levels of clinical agreement
  • Patients achieved an INR test within their target therapeutic range on 65.5% of occasions, which compared favourably with previous evaluation of target therapeutic range achievement within our Anticoagulation Clinic (63.4%)[4, 30]
  • No bleeding or thrombotic adverse events occurred

Parent feedback regarding the benefit of participating in the home INR monitoring program was high (9.4 out of 10). A study investigating the impact of participation in a home INR monitoring program upon quality of life demonstrated that such a program successfully reduces the burden of anticoagulant therapy and facilitates the empowerment of the child and family.[31] The results support the notion proposed in the literature that despite their chronic illness children are able to make the best of life but that their opportunity to live a normal life was hindered by their oral anticoagulant therapy and the demands of frequent INR testing.[31] Quality of life as an additional outcome measure of anticoagulation therapy in children ensures children and families values are integrated with the current recommendations based on safety and efficacy.[32]

Funding Considerations

Funding considerations regarding the initiation of home INR monitoring programs will vary significantly, largely due to the diverse health funding arrangements that exist between countries. Funding models developed by clinical agencies need to incorporate the upfront costs of INR monitors and the ongoing costs of consumables, inclusive of test strips and lancing devices. In addition, funding for the personnel supporting these programs is imperative as ongoing monitoring of individual patients and collective clinical outcomes is needed to ensure timely evaluation of the program's safety and efficacy outcomes.

The long-term feasibility of home INR monitoring programs necessitates strategic planning regarding the issue of ongoing funding. Funding models include state or national health funding, co-payment by families, philanthropic support and commercial company support. In order to develop the home INR monitoring program at the Royal Children's Hospital to its current level of supporting over 80 families, a combination of all these funding arrangements has been used across the last 9 years. Certainly, philanthropic and commercial support has proved vital in the conduct of research evaluating the outcomes of this program across that time span.


The initiation and ongoing development of the home INR monitoring program at the Royal Children's Hospital has been underpinned by a commitment to evaluate the program from the very outset. This paper provides quantifiable evidence supporting not only the clinical outcomes of the program but also process evaluation outcomes that have been rigorously conducted throughout the course of this program's existence. The processes reported within this paper will thus assist other clinical agencies seeking to establish and evaluate similar program within their organisations.


Thank you to Roche Diagnostics (Australia) who provided financial and in-kind support for the paediatric validation studies of the Coaguchek S and XS instruments.

Thank you to the Brockhoff Foundation who provided financial support for the study investigating the impact of home INR monitoring upon quality of life in children and their families.