title: Health literacy and warfarin therapy at two anticoagulation clinics in Brazil.
abstract: Health literacy has been related to health-related conditions and health outcomes. Studies examining the association of health literacy and anticoagulation have had variable results. We sought to investigate the relations of health literacy and percentage of time in therapeutic range (TTR) in a vulnerable Brazilian cohort at two hospital-based anticoagulation clinics.
  
  
  
  We measured health literacy with the Short Assessment of Health Literacy for Portuguese-speaking Adults (SAHLPA-18) in 2015-2016. We identified the demographic and clinical characteristics associated with health literacy and related health literacy to TTR.
  
  
  
  We enrolled 422 adults prescribed chronic warfarin therapy in our observational study (median age 62.1 years; 58.8% women; monthly income $200.00). The prevalence of inadequate health literacy (score 0-14 points) was 72.3% with a median score of 12 (quartiles, Q1=10; Q3=15) on the SAHLPA-18. The median TTR was 66.1%. In the multivariable logistic analysis, cognitive impairment and assistance with taking warfarin were associated with inadequate health literacy. Prosthetic heart valves and more school years were associated with adequate health literacy. Our analyses showed no significant relation between health literacy and TTR, analysing health literacy as a categorical (adjusted OR 1.05; 95% CI 0.65 to 1.70) or continuous variable (Spearman's coefficient 0.02; p=0.70).
  
  
  
  Inadequate health literacy was highly prevalent in this impoverished Brazilian cohort receiving anticoagulation with warfarin. However, we did not identify an association between health literacy and TTR. Future investigations may consider the systemic factors that contribute towards successful anticoagulation outcomes for vulnerable patient cohorts with inadequate health literacy.
authors.affiliation: Hospital das Clínicas and Faculdade de Farmácia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.|Sections of Cardiovascular Medicine and Preventive Medicine, Boston Medical Center, Boston University School of Medicine, Boston, Massachusetts, USA.
authors.forename: Maria Auxiliadora Parreiras
authors.initials: MAP
authors.lastname: Martins
authors.affiliation: Hospital Risoleta Tolentino Neves, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Josiane Moreira
authors.initials: JM
authors.lastname: Costa
authors.affiliation: Centro de Pesquisa René Rachou/Fundação Oswaldo Cruz, Av. Augusto de Lima, Barro Preto, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Juliana Vaz de Melo
authors.initials: JVM
authors.lastname: Mambrini
authors.affiliation: Hospital das Clínicas and Faculdade de Medicina da Universidade Federal de Minas Gerais, Av. Prof. Alfredo Balena, Bairro Santa Efigênia, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Antonio Luiz Pinho
authors.initials: ALP
authors.lastname: Ribeiro
authors.affiliation: Boston University and National Heart, Lung, and Blood Institute's Framingham Heart Study, Framingham, Massachusetts, USA.|Sections of Cardiovascular Medicine and Preventive Medicine, Boston Medical Center, Boston University School of Medicine, Boston, Massachusetts, USA.|Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts, USA.
authors.forename: Emelia J
authors.initials: EJ
authors.lastname: Benjamin
authors.affiliation: Hospital das Clínicas and Faculdade de Medicina da Universidade Federal de Minas Gerais, Av. Prof. Alfredo Balena, Bairro Santa Efigênia, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Luisa Campos Caldeira
authors.initials: LCC
authors.lastname: Brant
authors.affiliation: General Internal Medicine, Boston University School of Medicine, Boston, Massachusetts, USA.
authors.forename: Michael K
authors.initials: MK
authors.lastname: Paasche-Orlow
authors.affiliation: Department of Medicine, Division of Cardiology, UPMC Heart and Vascular Institute, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors.forename: Jared W
authors.initials: JW
authors.lastname: Magnani
mesh_terms: D000284:Administration, Oral; D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage; D001777:Blood Coagulation / Q000187:drug effects; D001938:Brazil; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D007722:Health Knowledge, Attitudes, Practice; D057220:Health Literacy / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013997:Time Factors; D016896:Treatment Outcome; D014859:Warfarin / Q000008:administration & dosage*; D016903:Drug Monitoring
chemical_list: D000925:Anticoagulants; D014859:Warfarin
keywords: anticoagulants; health literacy; health services; heart diseases; teaching hospitals; warfarin