Recommendations for point-of-care home International Normalized Ratio testing in children on vitamin K antagonist therapy.

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 (VKAC) 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.