Background Studies have shown an increased frequency of fibromyalgia (FM) in patients with rheumatoid arthritis (RA), which according to different authors was between 12-17% 1,2. A recent study found that the fibromyalgia tender point count significantly influenced the DAS28 score even in the non-FM range2.
Objectives The aim of our study was to assess the frequency of tender points (TP) in patients with RA and to explore the relationship between them and clinimetric evaluations.
Methods Consecutive outpatients with RA (ACR/EULAR´10 criteria) who attended to the Tornú Hospital’s Rheumatology Section between March and June 2012 were included. All patients underwent a standardized clinical assessment performed by one of the authors (MMA), including the evaluation of the number of swollen/tender joints (66/68), and TP assessment. Demographic data, disease characteristics, morning stiffness, VAS (pain, patient and physician global assessment) were evaluated and ESR and CRP determined. Patients were asked to complete HAQ, RAQoL and RAID. Finally, DAS28 and SDAI were calculated. Statistical analysis: The correlation between clinical parameters and TP was determined by Pearson correlation coefficient (r). We considered an r value > 0.5 as correlation. ANOVA compared the means of every single clinimetric parameter among 3 groups of RA patients (absence of TP vs 1-5 TP vs ≥ 6 TP). Statistical evaluation was performed by SPSS Statistics 17.0.
Results A total of 100 patients were included; 84% were women. The mean age was 53 (SD 11) years and the median symptoms duration was 60 (RIQ 36-120) months. Thirty five percent presented subcutaneous nodules, 98% rheumatoid factor positive, 85% APCA positive and 77% radiographic bone erosions. Regarding treatment, 34% used glucocorticoids, 76% DMARD (61% methotrexate) and 12% biological therapy. Thirty three percent had morning stiffness lasting more than 1 hour. Patients showed a mean DAS28 score of 4.31 (DS 1.5), HAQ 1.2 (DS 0.75), RAQoL 15 (DS 8), RAID 5.3 (DS 2.5) and VAS patient global assessment 47 mm (SD 28); and a median SDAI score of 13 (RIQ 5-23). Of the 100 patients studied, 8 (all women) fulfilled FM criteria (ACR ‘90) and were excluded from analyses. Among the remaining 92 patients, the median TP was 1 (RIQ 0-4), 49% had no TP, 30% had 1-5 TP, and 21% had ≥ 6 TP. The number of TP correlated with the number of tender joints (r = 0.563 p < 0.01). When evaluating patients per group (absence of TP vs 1-5 TP vs ≥ 6 TP), higher values were observed in DAS28 (5.9, DS 1.2), SDAI (31.3, DS 16.6), HAQ (1.5, DS 0.6), RAQoL (20.7, DS 6.3), RAID (6.12, DS 2.5) and VAS patient global assessment (72 mm, DS 15.9) in the group with TP ≥ 6 (p <0.01).
Conclusions The association between RA and FM was observed in 8% of the cases. The TP were found in 51% of RA patients without FM. The group of RA patients with ≥ 6 TP had a higher disease activity, a worse physical function and quality of life.
Wolfe F, Michaud K. Severe rheumatoid arthritis (RA), worse outcomes, comorbid illness, and sociodemographic disadvantage characterize RA patients with fibromyalgia. J Rheumatol 2004;31:695-700.
Ton E, Bakker MF, Verstappen S, Borg T, van Albada I, Schenk Y, et al. Look beyond the DAS28: tender points influence the DAS28 in patients with rheumatoid arthritis. J Rheumatol 2012;39:22-7.
Disclosure of Interest None Declared