title: Health literacy and health-related quality of life in adults with type 2 diabetes: a longitudinal study.
abstract: To examine the association of health literacy (HL) with changes in health-related quality of life (HRQL) among patients with type 2 diabetes.
  
  
  
  Data from a cohort study of type 2 diabetes patients were used. HL was assessed using 3 previously validated screening questions and HRQL using the EQ-5D-5L and SF-12 [physical and mental composite summary scores (PCS, MCS)]. The associations of baseline HL with changes in EQ-5D, PCS, and MCS scores over 1 year and with directions of changes (no change; declined; improved) were examined. Missing data were handled with multiple imputation and sensitivity analyses.
  
  
  
  Average age of participants (N = 1948) was 64.6 ± 10.9 years, 45 % were female, and 12.6 % had inadequate HL. Participants had mean decrements of 0.01 in EQ-5D, 1.0 in PCS, and 1.2 in MCS over 1 year. In adjusted analysis, HL was not associated with changes in EQ-5D over 1 year (β = 0.01, P = 0.146); however, patients with adequate HL had 2.1 points greater increase in PCS (P < 0.001) and 3.1 points in MCS (P < 0.001) compared to those with inadequate HL. Patients with adequate HL were less likely to have a decline in EQ-5D (RR 0.66; 95 % CI 0.44, 0.98), PCS (RR 0.51; 95 % CI 0.34, 0.76), and MCS (RR 0.49; 95 % CI 0.33, 0.72) compared to those with inadequate HL. Patients with adequate HL were more likely to have an improvement in MCS compared to those with inadequate HL (RR 1.78; 95 % CI 1.04, 3.04); such associations were not observed for PCS or EQ-5D. All results were robust in sensitivity analyses.
  
  
  
  Inadequate HL was independently associated with worsening HRQL in adults with type 2 diabetes, particularly in the mental health domain.
authors.affiliation: Alliance for Canadian Health Outcomes Research in Diabetes, University of Alberta, Edmonton, AB, Canada.
authors.forename: Fatima Al
authors.initials: FA
authors.lastname: Sayah
authors.affiliation: Alliance for Canadian Health Outcomes Research in Diabetes, University of Alberta, Edmonton, AB, Canada.
authors.forename: Weiyu
authors.initials: W
authors.lastname: Qiu
authors.affiliation: 2-040 Li Ka Shing Centre for Health Research Innovation, Alliance for Canadian Health Outcomes Research in Diabetes, School of Public Health, University of Alberta, Edmonton, AB, T6G 2E1, Canada. jeff.johnson@ualberta.ca.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Johnson
mesh_terms: D000368:Aged; D000416:Alberta; D003924:Diabetes Mellitus, Type 2 / Q000523:psychology*; D005260:Female; D007722:Health Knowledge, Attitudes, Practice; D057220:Health Literacy; D006304:Health Status; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008603:Mental Health; D008875:Middle Aged; D011788:Quality of Life; D011795:Surveys and Questionnaires
keywords: Health literacy; Longitudinal; Quality of life; Type 2 diabetes