Background Patient global disease activity score (PGDA) in patients with rheumatoid arthritis (RA) represents the patient's evaluation of disease and is included as one of four variables in the DAS28 score. Ultrasound (US) is a valid tool for assessing synovitis. However, there are no studies on how PGDA relates to US in patients with established RA during treatment.
Objectives To explore the associations between PGDA and subjective as well as objective measures of disease activity, including US, during one year follow-up of RA patients starting biologic medication.
Methods 213 patients (82% women, 80% anti-CCP positive, mean (SD) age 52.4 (13.4) years with 10.2 (8.6) years of disease duration) were included and assessed at baseline when starting biologic medication, and after 1, 2, 3, 6 and 12 months. PGDA was assessed on a 100mm visual analogue scale (VAS). US was performed of 36 joints (MCP 1-5, PIP 2-3, wrist (RC, IC, RU), elbow, knee, talo-crural, MTP 1-5 bilaterally) and 4 tendons (Ext. carpi ulnaris and Tib. post bilaterally), all scored 0-3 of grey scale (GS) and power Doppler (PD)) by one sonographer (HBH) (Siemens Antares), and the total sum scores of GS and PD from all joints/tendons were calculated. Patient reported outcomes (PROs) included pain VAS, the Rheumatoid Arthritis Impact of Disease (RAID) score (including questions on pain, functional capacity, fatigue, physical and emotional wellbeing, quality of sleep and coping) with calculation of total RAID score, modified HAQ (MHAQ), fatigue VAS, Hospital Anxiety and Depression Scale (HADS) with calculation of total sum scores. Patients scored their joint pain 0-3 in 36 joints on a figure, and sum scores were calculated. Two questions from the Coping Strategies Questionnaire were used for assessing catastrophizing, and mean scores were calculated and divided into quartiles. Clinical examinations were performed by a study nurse including Investigator's global VAS and tender and swollen joints (28 DAS joints and bilateral ankles and MTP joints (evaluated united), i.e. 32 joints). The sonographer and study nurse had no access to each other's assessments. Improvement during treatment was explored by paired sample t-test, associations across quartiles by ANOVA, and Pearson correlations were used for associations between PGDA and the PROs, clinical and US assessments.
Results At one year follow-up, 153 patients (72%) were still on the same biologic medication, and for these patients PGDA, all PROs, clinical and US assessments improved significantly (p<0.001) (illustrated for PGDA in figure A). Highly significant associations with degree of catastrophizing were found for PGDA (figure B) as well as for all the PROs (p<0.001), while number of swollen joints, CRP or US examinations were not associated with catastrophizing. The correlation coefficients during follow-up are shown in the table, with high associations between PGDA and all the PROs and very low/no association with laboratory and US findings.
Conclusions In this cohort of established RA, PGDA was highly associated with catastrophizing as well as with subjective assessments of disease activity, but only weakly or not at all with objective measures including US. The present discrepancy of patient experience and US findings should be further explored in studies also including recent onset RA.
Disclosure of Interest None declared