VERITAS-PRN: a new measure of adherence to episodic treatment regimens in haemophilia

Episodic treatment of bleeding disorders is defined as utilization of clotting factor concentrates in response to acute bleeding episodes to achieve haemostasis. Non-adherence to prescribed episodic regimens can limit treatment effectiveness and result in target joint formation, pain and disability. Evaluation of and interventions to promote adherence may improve health outcomes. The purpose of this study was to validate a new adherence scale developed for individuals with bleeding disorders treated on episodic infusion regimens, entitled VERITAS-PRN [Validated Hemophilia Regimen Treatment Adherence Scale - PRN]. Participants were recruited from the Indiana Hemophilia and Thrombosis Center patient population. Participants completed the scale for psychometric development and analysis. Subjective ratings of adherence from participants and providers were used for validation. The study sample included 51 male and three female patients. Twenty-seven participants (50.0%) were diagnosed with FVIII deficiency, 21 (38.9%) with FIX deficiency and six (11.1%) with von Willebrand's disease (VWD). Internal consistency reliability for the total VERITAS-PRN score and the majority of subscales was good-to-excellent, with the one exception being the 'Plan' subscale. Test-retest reliability correlations were good-to-excellent for the total scale and all subscales. The VERITAS-PRN total scale had moderate-to-strong and statistically significant correlations with validity measures. The VERITAS-PRN is a reliable and valid measure of adherence to episodic treatment regimens for bleeding disorders. This tool may be utilized as a standard measure of adherence to increase sensitivity to adherence problems and promote targeted interventions to enhance adherence and health outcomes.