The Association of Fibromyalgia Symptoms with SLE Outcome and Diagnosis  Robert S. Katz1, Frederick Wolfe2, Kaleb Michaud2, Carisa M. Cooney3

1Rush University Medical Center, Chicago, IL; 2National Data Bank for Rheumatic Diseases, Wichita, KS; 3Oklahoma Medical Research Foundation, Oklahoma City, OK

Abstract

PURPOSE. To describe the association between fibromyalgia symptoms and systemic lupus erythematosus (SLE) diagnosis and outcome.

METHODS. We studied 421 patients with SLE diagnosed by rheumatologists and compared them to 10,492 patients with other rheumatic disorders. Fibromyalgia was identified using survey fibromyalgia criteria (VAS fatigue score >= 6 and a Regional Pain Score (RPS) >= 8) and further analyzed as a continuous variable as the Symptom Intensification scale (SIS) (fatigue + (RPS/2))/2. We used the 4 quartiles of the SI Scale to classify patients according to the degree of fibromyalgia symptoms. All patients in Quartile 4 and 33% of patients in Quartiles 3 satisfy fibromyalgia criteria. Quality of life (QOL) was determined using the EQ-5D utility.

RESULTS. Using multivariate regression, we determined that photosensitivity Raynaud’s, rash, oral ulcers, purpura, pleurisy, low WBC, low platelet count, vasculitis, renal disease, age sex, ethnicity, hydroxychloroquine and prednisone best separated SLE and non-SLE patients (area under ROC = .91); and the 8 symptoms from a review of systems (ROS) described above had a ROC curve of 0.79 alone. Additionally, the 8 ROS variable were summed to make a Lupus ROS scale (0-8). Among SLE patients, 31% satisfied FM criteria, 18% had vasculitis and 35% had renal disease (Table 1). We examined the relation between lupus symptoms and degree of fibromyalgia in Figure 1 where it can be seen that SLE symptoms increased stepwise in each quartile of the SI scale. Similarly, Table 1 showed strong and statistically significant associations between the SLE symptom scale, VAS pain, Social Security disability, QOL and direct medical costs; by contrast, there were weak or no associations with vasculitis, renal disease and SLE treatment.

CONCLUSIONS. Fibromyalgia (characteristics) exists as a continuum among SLE patients rather than as a dichotomous condition, and there is no clear separation of fibromyalgia status at any level of the SI scale. Fibromyalgia symptom intensity reflects the total burden of SLE illness, as manifested by pain intensity, QOL and medical costs. This association is similar to what is seen in all other rheumatic disorders and suggests that fibromyalgia diagnosis and symptoms are a response to illness severity

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Pro

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1 2 3 4Quartiles of fibromyalgia intensity

Association of SLE predictors with fibromyalgia in 437 SLE patients

Low PlateletsLow WBCPleurisyRaynauds

Oral UlcersRashPhotosensitivity

Purpura

Figure 1. The Symptom Intensity Scale: A Measure of Fibromyalgianess

•31% of patients with SLE and 19% of patients without SLE satisfied survey fibromyalgia criteria

References

F. Wolfe and J. J. Rasker. The symptom intensity (SI) scale, fibromyalgia, and the meaning of fibromyalgia-like symptoms. J Rheumatol. November 2006.

R. S. Katz, F. Wolfe, and K. Michaud. Fibromyalgia diagnosis: A comparison of clinical, survey, and American College of Rheumatology criteria. Arthritis Rheum. 54 (1):169-176, 2006.

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.8

Pro

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Not Fibromyalgia Fibromyalgia

Not SLE SLE Not SLE SLE

Comparison of SLE symptoms in Patients with and without SLE

Low PlateletsLow WBC

PleurisyRaynaudsOral UlcersRash

PhotosensitivityPurpura

•Fibromyalgia (characteristics) exists as a continuum among SLE patients rather than as a dichotomous condition

•There is no clear separation of fibromyalgia status at any level of the SI scale.

•Fibromyalgia symptom intensity reflects the total burden of SLE illness, as manifested by pain intensity, QOL and medical costs. This association is similar to what is seen in all other rheumatic disorders and suggests that fibromyalgia diagnosis and symptoms are a response to illness severity

Table 1. Quartiles of Fibromyalgia Symptom Intensity and SLE Outcomes