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Patients With RA Find PGA-VAS Confusing, Unreliable for Ranking Disease States
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Vulnerable patients with rheumatoid arthritis experience difficulty with the patient global assessment of disease activity as measured by visual analogue scale, with about 40% finding it confusing, according to findings published in Arthritis Care & Research.
“This study is important because it shows that many of our subjects found the widely used visual analog scale patient global assessments (PGA-VAS) instrument confusing,” Joel Hirsh, MD, of the Denver Health and Hospital Authority, told Healio Rheumatology. “This is concerning given that different versions of the PGA-VAS are included in all RA composite disease activity indices.”
To analyze the views of vulnerable patients regarding PGA-VAS and model disease states, the researchers conducted an observational, cross-sectional study of 300 individuals with RA enrolled at Denver Health, a safety-net hospital. Participants completed the DAS28-PGA-VAS and Multidimensional Health Assessment Questionnaire (MDHAQ-PGA-VAS), as well as a survey asking if they found these PGA-VAS confusing. The participants also scored remission as well as mild, moderate and severe disease states.
The researchers performed analyses through summary statistics, linear and logistic regression. Outcomes included patient confusion regarding the PGA-VAS, whether patients’ responses to the model disease states followed a natural progression — remission, mild, moderate and severe — and whether remission model responses met Boolean and simplified DAS-based criteria.
According to the researchers, approximately 40% of participants thought the PGA-VAS was confusing, with lower health literacy and depressive symptoms being associated with confusion. In addition, less than a quarter of patients ranked the model disease states with the natural progress. Those who accomplished this goal were more likely to have higher health literacy, the researchers wrote.
“Model disease states have been proposed as a possible mechanism to help orient RA patients in terms of how to complete the PGA-VAS,” Hirsh told Healio Rheumatology. “Our study showed, however, that our subjects struggled with these as well. Limited health literacy predicted both confusion regarding the PGA-VAS and the model disease states. The clinical and research significance of our study is that we need to reevaluate the prominent role that the PGA-VAS plays in RA care and research studies. We also need to do better as a rheumatology community creating patient reported outcomes that are easier for all patients to understand and complete.” – by Jason Laday
Disclosure: Hirsh reports grant support from UCB. Please see the study for all other authors’ relevant financial disclosures.
Perspective
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Mark E. Pearson, MD, FACR
Breakthroughs have occurred rapidly in a number of medical specialties, including rheumatology. Our biologic medications have changed the goals of treatment in rheumatoid arthritis to include remission and low disease activity (LDA); however, response to these medications is quite variable. Other specialties, such as oncology, have objective parameters — including laboratory testing and radiology — to determine if new expensive medications achieve the goal of remission.
Although rheumatologists have new tests such as Vectra and musculoskeletal ultrasound (MSUS), their ability to define remission or LDA have not been adequately demonstrated; therefore, patient opinion of response is used to help define a good outcome. Our accepted measured parameters, such as clinical disease activity index (CDAI) or simple disease activity index (SDAI), include patient response to treatment on a visual analog scale (VAS) in addition to physician clinical evaluation, such as swollen and tender joint count.
The study from Hirsch and colleagues questions the validity of using the VAS in all population groups, demonstrating that a significant percentage (40%) of patient responses were influenced by literacy rates and symptoms of depression. The authors also postulate that osteoarthritis may impact response. These factors, including the importance given to the response in calculating a CDAI or SDAI, may result in incorrectly classifying a state of remission or LDA.
We need objective measures for RA treatment to determine if our medications result in the desired outcomes of remission or LDA. Attempts, such as the CDAI and SDAI, have been of benefit in this regard. This study indicates that more work may be needed to incorporate a valid patient response into the measurements, such as improved wording of questions and patient education as to symptoms related specifically to RA, as suggested by the authors. If standardization cannot be accomplished by these changes, relying more heavily on physician responses or awaiting studies using newer laboratory or radiologic procedures may be required to justify the continued use of our existing expensive medications.
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