Fibromyalgia (FM) is a controversial construct. Recently suggested survey criteria identify persons with FM characteristics without physical examination or clinical diagnosis, thereby obviating many of the objections to FM. Little is known about FM among patients with rheumatoid arthritis (RAF). We used the survey definition to characterize persons with RAF and to obtain insight into possible pathogenic mechanisms.
A total of 11,866 patients with RA completed the Regional Pain Scale (RPS) and a 0-10 visual analog scale (VAS) for fatigue. FM was diagnosed in patients with an RPS score > or = 8 and a VAS fatigue score > or = 6.
Altogether 1731 (17.1%) patients with RA fulfilled the criteria. Fewer RAF patients were married (64.9% vs 69.8%) and more were divorced (14.8% vs 10.4%); fewer were college graduates (19.7% vs 28.1%) and more did not finish high school (15.0% vs 8.9%). We found 35.8% of patients with FM but only 21.5% of those without FM had incomes less than 185% of the US poverty guidelines. Patients with RAF had higher validated hospitalization rates for major comorbid conditions and received treatment for comorbid conditions more often (expressed as odds ratios and 95% confidence interval): hypertension (1.5, 1.4-1.7), cardiovascular (1.8, 1.6-2.0), diabetes (1.9, 1.6-2.3), and depression (2.7, 1.8-4.2). RAF were 3.3 (3.0-3.7) times more likely to have been work-disabled (54.5% vs 26.4%) or to have total joint replacement (14.0% vs 11.2%; OR 1.3, 1.1-1.5), and incurred greater direct 6-month medical costs (6477 vs 4687 US dollars). RAF patients had more severe symptoms across all scales, including the Health Assessment Questionnaire (1.8 vs 1.0), pain (6.7 vs 3.4), Medical Outcomes Study Short Form-36 (SF-36) physical component score (23.5 vs 33.5), SF-36 mental component score (29.5 vs 46.1), and quality of life assessed by EuroQol mapped utilities (0.33 vs 0.65).
FM exists in a substantial number of patients with RA (17.1%), who have more severe RA by subjective and objective measures, greater medical costs, worse outcomes, more comorbidities, sociodemographic disadvantage, and substantially worse quality of life. We hypothesize that illness severity and sociodemographic disadvantage both play a role in producing the clinical picture of FM.