Arthritis & Rheumatism, Volume 63,
November 2011 Abstract Supplement
Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Chicago, Illinois November 4-9, 2011.
Quantifying the Contributors to Global Assessment of Rheumatoid Arthritis Disease Activity by the Patient and the Physician.
Studenic1, Paul, Smolen2, Josef, Aletaha1, Daniel
The perception of disease activity in RA often differs between physicians and patients, as can be realized by a disconnect between patient and physician global assessments (PGA, MDGA). In previous studies, swollen joint count (SJC) and pain were identified as main determinants of a higher MDGA and PGA, respectively. It is unknown, however, to what extent patients relate higher pain levels, and physicians higher joint counts, to their global assessments. We aimed to investigate how much variability of the PGA and MDGA are explained by pain, SJC and other core set variables.
We identified RA patients from an observational, prospective RA outpatient database, and obtained visual analogue scores (VAS) for PGA and MDGA. We performed a stepwise linear regression model, using PGA as dependent variable, and other core set variables as independent variables: pain scores on VAS, swollen and tender joint counts (SJC and TJC), functional scores by the Health Assessment Questionnaire Disability Index (HAQ), morning stiffness in minutes (MST), as well as C-reactive protein (CRP) and rheumatoid factor in units/ml (RF). We identified the variability of PGA explained by the variables selected by the model using a p<0.05 cutpoint for entry and p>0.10 for removal. We then repeated the same analysis using MDGA as the dependent variable.
We identified 634 RA patients (80% female, 68% RF positive, mean disease duration: 7.7 years). In the stepwise model pain, HAQ scores, and SJC remained significant (p<0.001 for each), explaining 79.3% of overall PGA variability mostly conveyed by pain (77.9%; see figure), while 20.7% of variability remained unexplained. For MDGA as dependent variable in the stepwise model SJC, pain, TJC and CRP were significant (p<0.0001 for each) explaining 65.2% of overall MDGA variability, mostly represented by SJC (58.1%, see figure), leaving 34.7% unexplained.
When all variables were included in a linear model, 93.1% of PGA was explained, indicating that the joint effects of these additional insignificant variables contributed another 14%, leaving only ~7% of PGA variability unexplained. For MDGA such model explained 84.2% of variability (further contribution of 19% by the insignificant variables), leaving 15.8% of MDGA variability unexplained.
Figure 1. Components of patient global assessment (PGA) and physician global assessment (MDGA) in percent.
The single greatest determinant of patient global is pain, explaining ~80% of its variability. In contrast, the global assessment of disease activity by the MD, on the other hand, is largely a reflection of the number of swollen joints involved. The larger unexplained proportion of variability of the MDGA may indicate, that physicians take more aspects of RA disease activity into account than reflected in the core set measures, and supports its use as an additional measure of RA disease activity assessment.
To cite this abstract, please use the following information:
Studenic, Paul, Smolen, Josef, Aletaha, Daniel; Quantifying the Contributors to Global Assessment of Rheumatoid Arthritis Disease Activity by the Patient and the Physician. [abstract]. Arthritis Rheum 2011;63 Suppl 10 :2146