Background/Purpose:

Assessment of disease activity is important in the evaluation and monitoring of patients with psoriatic arthritis (PsA) in clinical care and research. As there is no single ‘gold standard’ variable for assessment of disease activity several markers of disease activity are used, among these “global assessment” by the patient (PaGl) and by the physician (PhGl). The agreement and interplay between PaGl and PhGl are not well clarified in patients with PsA, however. The objective of the study was to examine associations on the group level and agreements on the individual patient level between PaGl and PhGl as scored on visual analogue scales (VAS) in the daily clinic by patients with active PsA and by their rheumatologists.

Methods:

Traditional disease activity data on 76 PsA patients with active disease planned to initiate biological treatment were extracted from the Danish DANBIO registry for biological treatment in rheumatology. Data comprised PaGl, PhGl and pain (0 – 100 VAS), 28 swollen and tender joint count, CRP, HAQ-DI and DAS28-CRP(4v). Analyses were performed using parametric statistics. The association between PaGl and PhGl was examined by simple linear regression analysis. The predictability of PaGl and PhGl, respectively, by all other disease markers mentioned and by age and sex was examined using stepwise multiple regression analysis. Agreement between the VAS scores was expressed as the bias (mean difference between intra-individual scores) and the 95% lower and upper limits of agreement (LLoA;ULoA) according to the Bland-Altman method.

Results:

Mean age was 52.2±11.1 years and mean DAS28-CRP 4.7±1.1. 59.2% of the patients were women. Mean PaGl was 63.7±23.2 and mean PhGl 39.9±19.8 (p < 0.0001). Thus the difference between PaGl and PhGl was substantial on the group level. Differences between PaGl and PtGl were even more pronounced on the individual level, however. The average difference was 23.8 (bias) but differences on the individual level ranged from -21.9 (LLoA) to +69.5 (UloA). The corresponding results for PaGl vs. pain was 4.9 (bias), -17.1 (LLoA) and 22.0 (ULoA), and for pain vs. PhGl 18.9 (bias), -23.0 (LLoA) and 60.8 (ULoA). PaGl was significantly but weakly correlated with PhGl (R = 0.42, p < 0.0001) with a high standard error of estimation (SEE) = 21.2. PaGl was independently predicted by pain (beta = 0.76, p < 0.0001) and HAQ-DI (beta = 0.19, p < 0.01) and was not predicted by PhGl (p = 0.61) (R = 0.78, SEE = 10.5, p < 0.0001). PhGl was independently predicted by SJC (beta = 0.43, p < 0.0001) followed by pain (beta = 0.41, p < 0.0001) and CRP (beta = 0.20, p < 0.05) (R = 0.70, SEE = 14.4, p < 0.0001) with no significantly contribution by PaGl (p = 0.49).

Conclusion:

In patients with active PsA initiating biological treatment, PaGl was in general scored considerably higher than PhGl. On the individual patient level, differences between PaGl and PhGl varied substantially. PaGl was best explained by pain, and PhGl by SJC. The findings reflect strongly diverging attitudes between PsA patients and their rheumatologists to severity of disease and to the relative importance of different outcome measures.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/patient-and-physician-global-assessment-are-poorly-inter-connected-and-poorly-explained-by-other-clinical-markers-of-disease-activity-in-individual-patients-with-psoriatic-arthritis/