Background Joint counts performed by rheumatologists, included in indices such as DAS (Disease Activity Score), are the main measure of disease activity in patients with Rheumatoid and Psoriatic Arthritis with peripheral joint disease. Nevertheless, self-reported outcomes are also used to assess disease activity and treatment response. Some authors defend that involving patients in disease activity assessment may enhance self-management behavior and improve health outcomes.1 Several studies have focused on the validity of self-reported joint counts. In a recent meta-analysis, authors concluded that in patients with Rheumatoid Arthritis (RA), self-reported tender joint count has moderate to marked correlation with those performed by a trained assessor; in contrast, swollen joint counts demonstrate lower levels of correlation.2 A recent study in Psoriatic Arthritis (PsA) suggested that patient's self-report has a poor correlation with physician's assessment.1
Objectives To compare the correlation between patient and physician's assessment in RA and PsA.
Methods A convenient sample of outpatients with RA and PsA attending a Rheumatology clinic was recruited. They were asked to fill out a questionnaire while they were in the waiting area. This included a disease activity visual analog scale (VAS) and three homunculi, in which the patients were asked to point tender, swollen and deformed joints out of 44 possible locations. After this, participants were examined by rheumatologists who also recorded tender, swollen and deformed joints, as well as disease activity VAS in physician's opinion. Statistical analysis was performed using IBM® SPSS® Statistics version 20. Spearman correlation coefficient (rs) was used to examine correlation between patient and physician's joint counts. The strength of the correlation is described as weak if rs<0.40, moderate for rs between 0.40 e 0.60, and strong if rs>0.60. Statistical significance was set at 0.05.
Results 114 patients were included, 68 with RA (75% females) and 46 with PsA (70% males).Mean age was 59±13 years in RA and 50±11 in PsA patients. Median disease duration was 4 years in both groups (interquartile range 2-9 in RA; 2-7.5 in PsA) and median DAS 28 (3) was 3.06 (2.06-3.93) in RA and 2.52 (1.67-3.43) in PsA. In RA group, the number of self-reported tender joints had moderate correlation with physician's assessment - rs=0.42, whereas swollen and deformed joint counts showed only weak correlation - rs=0.35 and 0.38 respectively. In PsA group, self-reported joint counts had moderate to strong correlation with physician's assessment. Spearman correlation coefficients were 0.62 for tender, 0.54 for swollen and 0.44 for deformed joints.
Conclusions The correlation between patient and physician's joint counts was stronger in PsA versus RA patients, contrary to reports in literature. The concordance was higher for tender joints in both groups.
Chaudhry, SR; Thavaneswaran, A; Chandran, V and Gladman, DD. Physician scores vs patient self-report of joint and skin manifestations in psoriatic arthritis, Rheumatol. Oxf. Engl., 2013; 52 (4): 705–711.
Barton, JL; Criswell, LA; Kaiser, R; Chen,Y-H and Schillinger, D. Systematic review and metaanalysis of patient self-report versus trained assessor joint counts in rheumatoid arthritis, J. Rheumatol., 2009; 36 (12): 2635–2641.
Disclosure of Interest None declared