Background/Purpose: PROs play a prominent role in evaluating patient status in rheumatic diseases. PROs often reveal disparities in individuals with low education or income or among racial/ethnic minorities. Limited health literacy (LHL) may also be more prevalent in these groups. While some have acknowledged that LHL may create challenges in disease management, the impact of LHL on PROs has received little attention. We examined the impact of LHL on PROs in a diverse SLE cohort.

Methods: Data were from the California Lupus Epidemiology Study (CLUES), a population-based, multi-ethnic SLE cohort (n=281). Subjects participated in an in-person research clinic, in which study physicians completed the SLEDAI and SLICC Damage Index (SDI), and completed a structured interview administered by a trained interviewer, in which the following PROs were administered: SF-36, short forms of ten PROMIS domains, and self-reported measures of disease damage and activity (Table). Health literacy was assessed using a 3-item validated scale¹. Individual education and household income were self-reported. Bivariate analyses examined differences in all PROs by education level (≤12 yrs vs. >12 yrs), income (≤125% of federal poverty level for household size vs. >125%), and LHL using t-tests. Multivariate linear regression analyses examined differences in PROs by LHL controlling for age, sex, race/ethnicity, disease duration, SLEDAI, SDI, education, and income.

Results: The sample was 29% white (W), 23% Hispanic (H), 11% African American (AA), and 37% Asian (AS); 89% female; mean age 45 (±14) years; 22% with education ≤high school; 12% with poverty-level income; mean disease duration 16 (±10) years. 85% of interviews were completed in English. 35% had LHL, with significant differences by race/ethnicity (W 21%, AS 36%, AA 42%, H 46%, p<.01). Physician assessments of SLE activity and damage were not significantly different by health literacy (p>0.50). Bivariate analyses showed significant differences in all PROs by LHL and income, but few differences by education. In multivariate analyses, significant differences by LHL remained in all PROs except self-reported disease damage, even after controlling for all covariates including income and education (Table).

Conclusion: Individuals with SLE and LHL had worse status as measured by a wide range of PROs, even after accounting for physician-assessed disease, income, education, and race/ethnicity. Whether differences are due to unmeasured effects of LHL or to differential interpretation of PRO measures by individuals with LHL is unknown. However, findings suggest that attention to health literacy is crucial in the development and validation of PROs to ensure that variations in scores reflect actual differences in the underlying construct and not differential understanding or interpretation of the questions.

¹Chew et al. Fam Med 2004; 36:588.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-impact-of-limited-health-literacy-on-patient-reported-outcomes-pros-in-systemic-lupus-erythematosus-sle/