Background Patient reported outcomes (PROs) are important for the evaluation of treatment response in patients with rheumatoid arthritis (RA). The degree of pain catastrophizing (conceptualized as a negative cognitive–affective response to anticipated or actual pain) may influence the patient's scoring of disease activity. Ultrasound (US) is a sensitive method for assessing inflammation, including grey scale synovitis (GS) and vascularization (power Doppler (PD)).
Objectives To explore the impact of pain catastrophizing on subjective outcomes and composite scores in comparison with objective outcomes, such as US-defined synovitis, during one-year follow-up of patients with RA starting treatment with biologic DMARDs (bDMARDs).
Methods A total of 209 patients with RA (mean (SD) age 53 (13) years, disease duration 10 (9) years, 81% women, 79% anti-CCP positive) were included when starting bDMARD. The patients were assessed at baseline and after 1, 2, 3, 6 and 12 months with PROs (joint pain VAS, patient's global disease activity VAS, Rheumatoid Arthritis (RA) Impact of Disease (RAID) score, MHAQ), clinical examination (assessor's disease activity VAS, tender and swollen joint counts (SJC) of 32 joints, performed by a study nurse) and laboratory variables (ESR and CRP). DAS28(ESR) and CDAI were calculated. Pain catastrophizing was assessed by the mean of two questions (each score 0–6) from the Coping Strategies Questionnaire (CSQ); “When I have pain, it's terrible and I think it's never going to get any better” and “When I have pain, I feel I can't stand it anymore”. All US examinations (semi-quantitative scoring (0–3)) of GS and PD (PIP 2–3, MCP 1–5, wrist (RC, IC, RU), elbow, knee, talo-crural, MTP 1–5 and extensor carpi ulnaris/tibialis posterior tendons bilaterally) were performed by one rheumatologist (HBH) (Siemens Acuson Antares, excellence version, 5–13 MHz probe). Correlations were explored by use of Spearman's, Wilcoxon explored changes from baseline and Mann-Whitney examined for differences between two independent groups.
Results 209 patients were included and 152 patients (72.7%) continued their bDMARD for the whole 12 months study. All variables, including pain catastrophizing, decreased significantly (p<0.001) during follow-up. Pain catastrophizing was highly correlated with patient reported outcomes (r=0.51–0.65, p<0.001), moderate with DAS28/CDAI (0.43/0.32, p<0.001) but not with CRP (r=0.1), SJC (r=-0.01) or GS (r=–0.06)/PD (r=-0.04) scores. All the subjective and composite scores were much higher (p<0.001) in patients with higher levels of pain catastrophizing (cut-off 1.5) (4 time points shown below), while there were no differences for CRP, SJC or US scores. All subjective and composite scores had increasing levels with increased quintiles of pain catastrophizing (p<0.001), while this was not found for CRP, SJC or US (some variables illustrated).
Conclusions It is generally assumed that the tendency to catastrophize plays a causal role in the pain experience which may influence the PROs. Pain catastrophizing was presently found to have a major impact on all the subjective as well as composite scores, but not on inflammatory variables like CRP, SJC or US assessments. This emphasises the importance of taking into account the degree of pain catastrophizing when evaluating disease activity in RA patients.
Disclosure of Interest None declared
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