Abstract
Purpose
To examine the association of health literacy (HL) with changes in health-related quality of life (HRQL) among patients with type 2 diabetes.
Methods
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.
Results
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.
Conclusions
Inadequate HL was independently associated with worsening HRQL in adults with type 2 diabetes, particularly in the mental health domain.
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Acknowledgments
Author’s contribution
F.A.S. and J.A.J. conceived this study. F.A.S. and W.Q. conducted the analysis. F.A.S. wrote the first draft of this manuscript, and all authors provided feedback and approved the submitted version. Fatima Al Sayah is the guarantor of this work and, as such, had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Funding
This work was supported by grant from Alberta Health and a CIHR Team Grant to the Alliance for Canadian Health Outcomes Research in Diabetes (Reference No.: OTG-88588), sponsored by the CIHR Institute of Nutrition, Metabolism and Diabetes (INMD).
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Ethical approval for the study was granted by the Health Research Ethics Board at the University of Alberta.
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Informed consent was obtained from all individual participants included in the study.
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Sayah, F.A., Qiu, W. & Johnson, J.A. Health literacy and health-related quality of life in adults with type 2 diabetes: a longitudinal study. Qual Life Res 25, 1487–1494 (2016). https://doi.org/10.1007/s11136-015-1184-3
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DOI: https://doi.org/10.1007/s11136-015-1184-3