Statistics from Altmetric.com
Rheumatoid arthritis (RA) is a chronic polyarticular disease characterised by pain in peripheral joints accompanied by swelling, stiffness, and functional impairment. In some cases it is associated with fibromyalgia (FM), a syndrome defined by chronic, widespread pain, asthenia, and sleep disorders. When a patient has both RA and FM, determining the degree of RA activity may be difficult, because these patients typically have higher scores for pain and disability.
This study aimed at evaluating whether there were differences in functional disability, extra-articular manifestations, and use of disease modifying antirheumatic drugs (DMARDs), between patients with RA with and without FM.
PATIENTS AND METHODS
A cross sectional study was conducted with 386 patients with RA, 94 men and 292 women, with a mean age of 53 years. All the patients met the criteria of the American College of Rheumatology (ACR) for the diagnosis of the disease.1 The mean duration of the disease was nine years. All the patients received treatment in a hospital outpatient clinic and were included in a database between 1991 and 2000. To diagnose FM, ACR criteria had to be fulfilled on at least two consecutive visits.2 The following assessment was made in all patients participating in the study: a clinical history, evaluation of functional status using the Health Assessment Questionnaire (HAQ),3 conventional laboratory measurements, and evaluation of the rheumatoid factor. In addition to these assessments, extra-articular manifestations were diagnosed. Secondary Sjögren's syndrome was diagnosed when, in addition to subjective xerophthalmia and xerostomia, Schirmer's test or the rose bengal staining were pathological.4 The number of previous DMARDs was counted, independently of whether the patient received a single drug or a combination.
Contingency tables were used to compare the frequency of categorical variables among the different groups. To compare numerical variables we used Student's t test when the data followed a normal distribution and the equivalent Wilcoxon non-parametric test when they did not.
Of the total, 57 (14.8%) patients fulfilled FM criteria. No differences were found in age or disease duration between patients with RA without FM (RA group) and patients with RA and FM (RA-FM group) (table 1). In the RA-FM group there was a higher percentage of women (p=0.03); HAQ scores (p=0.002) were also higher. The incidence of extra-articular manifestations such as serositis, pneumonitis, or Sjögren's syndrome was similar in both groups. Rheumatoid nodules and the rheumatoid factor were more common in the RA group, although differences were not significant. The RA-FM group had received a greater number of DMARDs (p=0.04).
The results of this study indicate that patients with RA who also have FM are more often women, have higher disability scores, and receive DMARDs more frequently.
Wolfe et al studied 242 patients with RA and 38 who had FM occurring in association with RA. The RA-FM group had more abnormal measures of function, pain, disease activity, and psychological status, but the disease severity in RA-FM and RA was similar.5 In patients with RA, FM tender points have been found to correlate mainly with daily stress and with higher joint tenderness count scores, indicating that patients with RA and FM have a lower pain threshold.6,7 Patients with RA and depression often perform fewer daily life activities.8
In summary, FM is found to be associated in one of seven patients with RA; the presence of FM may constitute a marker of a worse prognosis for subjective functional disability.