Limited health literacy has been associated with poor health outcomes in several rheumatoid arthritis (RA) studies. For RA patients in the U.S. with limited health literacy or English proficiency, the patient global assessment of disease activity as measured by a visual analog scale (PGA-VAS) may not adequately capture their true disease activity. These vulnerable patients may have difficulty completing the PGA-VAS. According to current guidelines, RA patients must have a low PGA score to confirm low disease activity or remission. Prior research has found limited health literacy may result in discrepancies between PGA-VAS and provider assessments of disease activity.
Joel Hirsh, MD, of the Denver Health and Hospital Authority and University of Colorado Medical School, Denver, and colleagues sought to understand the perspectives of vulnerable patients regarding PGA-VAS. In a cross-sectional study, 300 participants with RA completed the PGA-VAS in the Disease Activity Score in 28 joints and the Multidimensional Health Assessment Questionnaire, as well as a questionnaire regarding these assessments. Participant health literacy was assessed using the modified Short Test of Functional Health Literacy in Adults (S-TOFHLA), which is validated in English and Spanish. Participants also completed a model of disease states and remission, ranking remission, mild, moderate and severe disease using VAS.
The researchers hypothesized that “many of our vulnerable subjects would find the PGA-VAS challenging.” Additionally, they thought sociodemographic variables, such as lower health literacy, would be associated with patients being unable to order the disease model states into a natural progression. The study’s results were published in the May 2019 issue of Arthritis Care & Research.
The Results
“Our primary hypothesis was confirmed,” write the authors in their discussion. “Our quantitative information about the PGA-VAS instruments from a diverse group of patients adds substantially to the literature regarding the patient perspective on PGA-VAS instruments.”
Approximately 40% of participants found the PGA-VAS confusing. According to the data, the most frequently selected reasons for this confusion were the variability in RA symptoms and the lack of certainty regarding whether RA was driving symptoms.
For both versions of the PGA-VAS, a positive depression screen was a significant predictor of confusion. Spanish-speakers were more likely to want help completing scales, while males and those with higher S-TOFHLA scores or higher education levels expressed a need for help less frequently for both versions of the PGA-VAS.
For the model disease states, 49% of participants completed them in a manner that did not have natural progression, and only 25% (n=76) completed them in a numerical manner with natural progression. Predictors for completing the model in a natural progression included income above the U.S. federal poverty line and a higher S-TOFHLA. Additionally, only 22% of participants (n=67) ranked the remission model at the threshold for remission.
The authors note that the surprisingly low number of patients correctly classifying a remission model disease state has wide implications for clinical practice and research. “It also raises the possibility of misclassification of disease activity based on patient reported outcomes in vulnerable populations, and more broadly, of how disease activity is classified according to patient reported outcomes,” they write.
“Our data … are particularly valuable and add urgency to the growing sense that the PGA-VAS needs to be re-examined as a criterion of remission,” conclude the authors. “Finally, we believe that if the PGA-VAS is to be kept as a key component of all RA disease activity indices, it should be made less confusing in terms of its wording, clarification of its target dimensions, and reduction of its literacy and numeracy burdens.”
Hirsh J, Wood P, Keniston A, et al. Limited health literacy and patient confusion about rheumatoid arthritis patient global assessments and model disease states. Arthritis Care Res (Hoboken). 2019 May;71(5):611–619.
