The Association of Health Literacy With Time in Therapeutic Range for Patients on Warfarin Therapy

Abstract

Patients on warfarin therapy need to achieve and maintain anticoagulation control in order to experience the benefits of treatment while minimizing bleeding risk. Low health literacy skills may hinder patients' ability to use and adhere to warfarin in a safe and effective manner. The authors conducted this study to evaluate the relationship between health literacy and anticoagulation control among patients on chronic warfarin therapy. Participants were recruited from 2 diverse anticoagulation clinics in North Carolina. Time in therapeutic range (TTR) for warfarin therapy was used as a measure of anticoagulation control. Health literacy was assessed using the short form of the Test of Functional Health Literacy in Adults (S-TOFHLA). Of the 198 study participants, 51% had limited health literacy (S-TOFHLA score of 0-90) and 33% had poor anticoagulation control (TTR<50%). Participants with limited health literacy were less likely to correctly answer warfarin-related knowledge questions. Limited health literacy was significantly associated with TTR<50% (adjusted odds ratio=2.34, 95% CI [1.01, 5.46]). Findings indicate that limited health literacy is associated with poor anticoagulation control for patients on warfarin therapy. Lack of medication understanding may hinder the safe and effective use of this narrow therapeutic index drug.

Relation between health literacy, self-care and adherence to treatment with oral anticoagulants in adults: a narrative systematic review

“…Different tools were used to assess cognitive ability, including the Cognitive Abilities Screening Instrument-Short Form (S-CASI), Short Portable Mental Status Questionnaire (SPMSQ), Animal Naming Test (ANT) and the ABILHAND (to measure of manual ability for adults) [ 34 , 39 – 43 ]. In terms of geographical location, nine studies were conducted in United States (US), [ 34 , 35 , 37 – 43 ] and one was originated from Australia [ 36 ]. No papers published in Europe were found.…”

“…No papers published in Europe were found. The most recent articles were published between 2014 and 2015 [ 37 , 40 ].…”

Rationale and design of the Atrial Fibrillation health Literacy Information Technology Trial: (AF-LITT)

“…[4] Limited health literacy has been associated with worse anticoagulation as measured by time in therapeutic range for warfarin, decreased understanding of stroke prevention, and symptom severity. [3,[5][6][7][8] Like other chronic diseases, individuals with limited health literacy may have further difficulty managing self-care, negotiating specialty clinics, adhering to treatments, and accessing resources. Such challenges may be worsened by social determinants of health related to health literacy, such as socioeconomic status and access to care.…”

Health literacy and warfarin therapy at two anticoagulation clinics in Brazil

“…5-7 11 22 Several studies have identified significant associations of health literacy with TTR. [5][6][7] In contrast, others have found no relation of health literacy and TTR in English-speaking and Spanish-speaking cohorts. 11 22 Of note, we found that the median TTR in our cohort was very high, even similar or greater than that observed in clinical trials (range 58.0%-68.4%).…”

“…[5][6][7] An association between health literacy and successful anticoagulation use is plausible because warfarin use is complicated by its narrow therapeutic index, wide variability in dose-response and need for frequent monitoring. 8 Health literacy has been related to understanding the rationale for anticoagulation; however, investigation of the relationship between health literacy and successful warfarin use has yielded mixed results.…”