SEARCH

SEARCH BY CITATION

Capillary point-of-care (POC) International Normalized Ratio (INR) measurement within the home is a feasible method of INR testing and is associated with non-inferior warfarin/INR control when compared with traditional approaches [1, 2]. Owing to the lack of studies providing evidence for guidance in POC INR Home Testing (PIHT), consensus recommendations have been developed for use in the pediatric community. Vitamin K antagonist therapy which includes all coumarin preparations (VKA-C) is monitored using the prothrombin time expressed as an INR, and conventional management consists of attending a laboratory for venipuncture. The POC INR meter requires a minimal blood sample, produces an immediate INR result and can be performed at the patients' convenience thereby eliminating the need for laboratory attendance [3, 4]. Laboratory attendance interrupts school and parent professional engagement potentially impacting adherence [5]. The convenience of PIHT facilitates more frequent INR testing which is necessary in children on VKA-C as a result of additional special challenges compared with adults [4].

The level of evidence in POC INR monitoring pediatric trials is weak owing to the methodological limitations inherent in most study designs employed. The incidence of major clinical complications is the best method for quality assessment but requires large patient numbers and is not feasible in pediatrics [1]. Minor complications are complex to evaluate and often not reported. Time in target therapeutic range (TTR) is commonly used as a surrogate measure for safety and efficacy of VKA-C therapy [6]; however, varied statistical methodologies are employed in pediatrics studies which may not be interchangeable. Children's reported laboratory TTR is approximately 50% [4]; however, previous studies have demonstrated that PIHT results in better control (TTR 60–84%) [1].

Currently, vitamin K antagonists will probably remain the most common oral anticoagulant used in children. Although novel oral anticoagulants are being tested in adults, pharmacokinetic studies in pediatrics are still in their infancy and necessary to guide pediatric dosing.

Recommendations and discussion

  1. Top of page
  2. Recommendations and discussion
  3. PIHT programs
  4. Considerations for developing point-of-care INR home testing programs
  5. Future directions
  6. Disclosure of Conflict of Interest
  7. References

PIHT testing can be performed accurately, has been demonstrated to be non-inferior to laboratory monitoring and is associated with patient preference [7, 8], and possibly improved the health-related quality of life [1, 9] This position paper recommends that PIHT be considered for children prescribed long-term VKA-C therapy (>3 months) such as children with prothrombotic conditions or in children with acquired or congenital heart disease requiring thromboprophylaxis.

PIHT programs

  1. Top of page
  2. Recommendations and discussion
  3. PIHT programs
  4. Considerations for developing point-of-care INR home testing programs
  5. Future directions
  6. Disclosure of Conflict of Interest
  7. References

PIHT programs have been conducted within dedicated pediatric anticoagulant clinics. Studies evaluating PIHT are largely cohort studies with only one randomized control trial (RCT) and are reviewed by Christensen et al. [1]. Further limitations to study design include sample size and the low number of warfarin patient-years reported.

Two models exist, patient self-testing and patient self-management, described below.

  1. Patient self-testing is when a child/parent performs an INR test at home and the result is reported to a health care provider. The health care provider recommends a VKA-C dosing plan with a follow-up testing interval. Patient Self Testing (PST) has been investigated in several studies ranging from 14 to 80 patients (mean 23) [1] with various indications for VKA-C, predominately case series design. The mean follow-up was 16 months and the TTR (63.0–83.9%) compared favorably with laboratory monitoring (50%) [4]. Patients who become adept and comfortable with PST will often transition to patient self-management over time.
  2. Patient self-management is when the patient takes an active role in his/her own treatment by performing a POC INR and self-adjusting the warfarin dose. This model is built upon standardized and comprehensive education, and requires the health care provider support during the ‘learning phase’, when dosing decisions are unclear to the patient/family, and for very low or high INRs. Patient self-management has been assessed in seven studies [1] using case series designs except in a single RTC where children were randomized to continue patient self-testing or commence patient self-management [10] In the randomized control trial, TTR was similar in both groups at 83%, with the patient self-management group reporting higher health-related quality of life and satisfaction with therapy [10, 11]

Considerations for developing point-of-care INR home testing programs

  1. Top of page
  2. Recommendations and discussion
  3. PIHT programs
  4. Considerations for developing point-of-care INR home testing programs
  5. Future directions
  6. Disclosure of Conflict of Interest
  7. References

Successful implementation of a PIHT program can be achieved through a clearly articulated plan incorporating quality assurance, education and training, maintenance and evaluation processes. A strategic approach to program development ensures that all requisite elements for success are considered and accommodated. There is no minimum number of patients required to initiate PIHT INR monitoring. PIHT can be established for one patient if the recommendations in this manuscript are adhered to. Educational information can be acquired from the manufacturers or other pediatric centers. Characteristics that preclude PIHT have not been identified in a systematic way in either adults or children. Until these characteristics are identified the health care provider and family should agree on the feasibility of this method of management. Time in target therapeutic range is demonstrated to increase in children using PIHT [1]. Therefore, children attending the laboratory with low TTR would be eligible and benefit from PIHT.

  1. Quality assurance
    1. In general, POC INR meters authorized for use have demonstrated accuracy and reliability and are considered adequate for monitoring of VKA-C therapy in adults and children [1, 6, 9, 12]. There a number of meters available on the market with the CoaguChek meter (Roche Diagnostics, Basel Switzerland) being the most studied in children [12, 13, 7]. Point of care meters have been demonstrated to be accurate and precise for use in children prescribed VKA-C therapy [7] with an average difference between the meter and laboratory INR of 0.13–0.67 [12].
    2. Recommendations strongly encourage POC INR and laboratory comparisons to be performed prior to clinical implementation of a meter both institutionally and in each patient with repeated comparisons every 12 months to confirm meter function, integrity of test strip thromboplastin and user proficiency in testing [1, 6, 9, 12].
  2. Self-Testing Models: processes for reporting results are described above (see Patient self-testing and Patient self-management).
  3. Mobile health programs are available with some having been evaluated to support patients with INR reminders, logging INRs, resources and with dose adjustments [14, 8].
  4. Staff and patient education
  5. Training/education equips staff with skills to train others in PIHT. Patient training is successfully achieved when health care providers who train patients are trained in the management of VKA-C therapy and are proficient in PIHT [1, 6, 15]. Proficiency in PIHT improves INR meter accuracy (r2 = 0.92) [16] compared with unqualified users (r2 = 0.87) [17]. Training should include theoretical and pharmaceutical aspects of anticoagulation, use of equipment, reporting of INRs and a practical session.
  6. Child and family education should be family centered and focus on knowledge of VKA-C action as well as proficiency in PIHT (see reference 19 for educational tools). Comprehensive standardized education that is interactive and incorporates proven learning techniques, including the use of sight, sound, touch and colour, accelerates the learners' acquisition of knowledge and skills [18]. Oral and written education should present the following key concepts [3, 19]:
  7. Clarify PIHT follow-up expectations for the patient/family for example performing INRs when recommended and calling results to the health care provider for VKA-C dosing instructions.
  8. Information on blood coagulation.
  9. Indication for VKA-C therapy.
  10. VKA-C mechanism of action, interactions with other medications and other influences on patient's clinical response to VKA-C (i.e. diet and viral infections).
  11. Potential adverse effects, safety issues: bleeding that does not stop with application of 10 min of firm pressure should be discussed with the health care provider at the time of the event. One of the advantages of PIHT is that immediacy of the INR result which can be responded to quickly.
  12. Practical skills of PIHT include testing proficiency, meter storage and test strip stability [6, 9].
  13. Importance of adherence: non-reported INRs must be followed up by the health care provider. Should this non-adherence to recommendations persist, the health care provider should work with the patient/family to promote adherence [5].

Pediatric PIHT programs should provide access to participants for queries at pre-specified times and 24-h availability for exceptional INR results, and in case of emergencies.

  1. Funding implications
    1. Funding of PIHT varies depending on the country and specific institution. Each institution should be aware of this aspect of program support prior to embarking on program development.

Future directions

  1. Top of page
  2. Recommendations and discussion
  3. PIHT programs
  4. Considerations for developing point-of-care INR home testing programs
  5. Future directions
  6. Disclosure of Conflict of Interest
  7. References

PIHT of VKA-C therapy in children affords considerable advantages, including ease of blood collection, immediacy of results, patient preference for PIHT and non-inferior if not better warfarin control. Given the current level of evidence for PIHT, well-designed studies are required to further evaluate PIHT-associated quality of life and long-term VKA-C control in patients performing PIHT [1].

References

  1. Top of page
  2. Recommendations and discussion
  3. PIHT programs
  4. Considerations for developing point-of-care INR home testing programs
  5. Future directions
  6. Disclosure of Conflict of Interest
  7. References
  • 1
    Christensen TD, Larsen TB, Hjortdal VE. Self-testing and self-management of oral anticoagulation therapy in children. Thromb Haemost 2011; 106: 3917.
  • 2
    Monagle P, Chan AKC, Goldenberg NA, Ichord RN, Journeycake JM, Nowak-Göttl U, Vesely SK. Antithrombotic therapy in neonates and children: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest 2012; 141: e737S801S.
  • 3
    Newall F, Bauman M. Point-of-care antithrombotic monitoring in children. Thromb Res 2006; 118: 11321.
  • 4
    Streif W, Andrew M, Marzinotto V, Massicotte P, Chan AK, Julian JA, Mitchell L. Analysis of warfarin therapy in pediatric patients: a prospective cohort study of 319 patients. Blood 1999; 94: 300714.
  • 5
    Sabaté E. Adherence to long-term therapies: evidence for action. 2003.
  • 6
    Ansell J, Jacobson A, Levy J, Voller H, Hasenkam JM; International Self-Monitoring Association for Oral A. Guidelines for implementation of patient self-testing and patient self-management of oral anticoagulation. International consensus guidelines prepared by International Self-Monitoring Association for Oral Anticoagulation. Int J Cardiol 2005; 99: 3745.
  • 7
    Greenway A, Ignjatovic V, Summerhayes R, Newall F, Burgess J, DeRosa L, Monagle P. Point-of-care monitoring of oral anticoagulation therapy in children. Comparison of the CoaguChek XS system with venous INR and venous INR using an International Reference Thromboplastin preparation (rTF/95). Thromb Haemost 2009; 102: 15965.
  • 8
    Ryan F, Byrne S, O'Shea S. Randomized controlled trial of supervised patient self-testing of warfarin therapy using an internet-based expert system. J Thromb Haemost 2009; 7: 128490.
  • 9
    Christensen TD, Larsen TB. Precision and accuracy of point-of-care testing coagulometers used for self-testing and self-management of oral anticoagulation therapy. J Thromb Haemost 2012; 10: 25160.
  • 10
    Bauman ME, Black K, Bauman ML, Bruce AAK, Kuhle S, Bajzar L, Massicotte MP. EMPoWarMENT: Edmonton pediatric warfarin self-management pilot study in children with primarily cardiac disease. Thromb Res 2010; 126: e110e5.
  • 11
    Bruce AAK, Bauman ME, Black K, Newton A, Legge L, Massicotte MP. Development and preliminary evaluation of the KIDCLOT PAC QL©: a new health-related quality of life measure for pediatric long-term anticoagulation therapy. Thromb Res 2010; 126: e116e21.
  • 12
    Bauman ME, Black KL, Massicotte MP, Bauman ML, Kuhle S, Howlett-Clyne S, Cembrowski GS, Bajzar L. Accuracy of the CoaguChek XS for point-of-care international normalized ratio (INR) measurement in children requiring warfarin. Thromb Haemost 2008; 99: 1097103.
  • 13
    Williams VK, Griffiths ABM. Acceptability of CoaguChek S and CoaguChek XS generated international normalised ratios against a laboratory standard in a paediatric setting. Pathology 2007; 39: 5759.
  • 14
    O'Shea SI, Arcasoy MO, Samsa G, Cummings SE, Thames EH, Surwit RS, Ortel TL. Direct-to-patient expert system and home INR monitoring improves control of oral anticoagulation. J Thromb Thrombolysis 2008; 26: 1421.
  • 15
    Newall F, Johnston L, Monagle P. A survey of pediatric cardiology nurses' understanding of warfarin therapy. Pediatr Cardiol 2006; 27: 2048.
  • 16
    Mahonen S, Riikonen P, Vaatainen RL, Tikanoja T. Oral anticoagulant treatment in children based on monitoring at home. Acta Paediatr 2004; 93: 68791.
  • 17
    Marzinotto V, Monagle P, Chan A, Adams M, Massicotte P, Leaker M, Andrew M. Capillary whole blood monitoring of oral anticoagulants in children in outpatient clinics and the home setting. Pediatr Cardiol 2000; 21: 34752.
  • 18
    Bauman ME, Black K, Kuhle S, Wang L, Legge L, Callen-Wicks D, Mitchell L, Bajzar L, Massicotte MP. KIDCLOT©: the importance of validated educational intervention for optimal long term warfarin management in children. Thromb Res 2009; 123: 7079.
  • 19
    Bauman ME, Massicotte MP, Ray L, Newburn-Cook C. Developing educational materials to facilitate adherence: pediatric thrombosis as a case illustration. J Pediatr Health Care 2007; 21: 198206.