Background/Purpose: Up to 20% of patients with RA have coexisting fibromyalgia(FM). This can make treatment decisions challenging in clinical practice as disease activity scores can be high despite limited clinical evidence of active synovitis. Recent work has suggested that a tender joint count (TJC) minus swollen joint count (SJC)(each out of 28) of ≥7 identifies patients with co-existing FM (‘fibromyalgic’ RA) with high sensitivity and specificity. Ultrasound (US) of joints particularly power Doppler is predictive of outcomes in RA patients. The aim of this study was to determine whether RA patients with active disease also meeting existing criteria for fibromyalgia had significantly less joint inflammation on ultrasound than those who did not.

Methods: 47 RA patients with DAS28 scores >2.6 were recruited. Patients completed questionnaires including the Widespread Pain Index(WPI), PHQ9(depression), GAD7(anxiety), PHQ15(somatisation), FACIT-fatigue, HAQ and global health assessment VAS.  The TJC, SJC, Symptom Severity Score(SSS) and the number of FM soft-tissue tender points were recorded by a physician. Patients underwent a 22-joint US scan by a second blinded physician of the wrists, MCPJs and PIPJs bilaterally. Grey scale(GS) and power Doppler(PD) scores were recorded for each joint on a semiquantitative scale (0-3) for each patient. FM patients were grouped according to the ACR 1990 classification criteria and TJC-SJC >7 individually and in combination. Differences between groups were tested using the Mann-Whitney U test. Significance was set at p<0.05

Results: GS scores were significantly lower in patients meeting ACR (GS score 16.7,p=0.025), TJC-SJC (16.7,0.034) or both criteria (15.4, 0.022) than in those who did not (21.8). PD scores were not significantly different for the individual criteria but when combined the scores for patients meeting both criteria were significantly lower compared with patients not meeting these criteria (PD score 2.94 vs 8.33, p=0.028). Significantly higher scores were seen for depression, anxiety, disability and somatization scores in patients meeting either or both FM criteria compared with those who did not.

Conclusion: Our findings show that RA patients who meet the 1990 ACR criteria for FM and who have a TJC minus SJC of ≥7 have significantly lower levels of synovitis on GS and PD US. This suggests that it may be possible to use clinical measures to identify patients not in DAS28 clinical remission into those with higher or lower levels of synovitis on US. Thus there may be a role for composite tools in clinical practice to stratify patients into those who may benefit from continued escalation of immunosupression and those who may benefit from alternative management strategies focussing on improving levels of depression, anxiety and fatigue. We are currently conducting a larger study to explore this further. 

Table 1.  Mean score, (SD), p value

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/clinical-features-of-fibromyalgia-in-patients-with-rheumatoid-arthritis-predict-lower-power-doppler-scores-on-ultrasound/