Outcome and Predictor Relationships in Fibromyalgia and Rheumatoid Arthritis: Evidence Concerning the Continuum versus Discrete Disorder Hypothesis
National Data Bank for Rheumatic Diseases, 1035 N. Emporia, Suite 288, Wichita, KS 67214, USA. The Journal of Rheumatology
(Impact Factor: 3.19).
03/2009; 36(4):831-6. DOI: 10.3899/jrheum.080897
To compare outcome-predictor relationships in fibromyalgia (FM) and rheumatoid arthritis (RA), to provide information regarding the competing hypotheses that FM is a continuum or a discrete disorder.
We studied 3 outcome variables (work disability, opioid use, depression) and 12 clinical predictor variables in 2,046 patients with FM and 20,374 with RA. We determined whether outcome-predictor relationships were stronger in FM or RA by measuring the areas under the receiver-operating curves. We used fractional polynomial logistic regression to create graphic models for the outcome-predictor relationships.
All measures of status and outcome were more abnormal in FM than in RA. Depression was reported in 33.4% of patients with FM compared with 15.1% of those with RA. The predictor-outcome relationship was significantly stronger in RA in 28 of the 36 tests, and not different in the remainder. The relationship between outcome and predictor variables was generally similar in patients with FM and RA. However, unmodeled depression that was not explained by study variables was noted in FM.
Our data are consistent with the hypothesis that FM is the end of a severity continuum, but that additional psychological factors are an integral part of the syndrome.
Available from: Enrico Bellato
- "Even though these criteria are useful for standardizing the diagnosis, they have been criticized: during these 20 years a number of practical and philosophical objections have been raised in relation to the 1990 ACR classification criteria. The most notable have been the criticisms about the use and interpretation of tender-point count [141, 142], the lack of consideration of associated symptoms [143–146], and neglect of the possibility that fibromyalgia might represent the extreme end of a widespread musculoskeletal pain continuum . "
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ABSTRACT: Fibromyalgia syndrome is mainly characterized by pain, fatigue, and sleep disruption. The etiology of fibromyalgia is still unclear: if central sensitization is considered to be the main mechanism involved, then many other factors, genetic, immunological, and hormonal, may play an important role. The diagnosis is typically clinical (there are no laboratory abnormalities) and the physician must concentrate on pain and on its features. Additional symptoms (e.g., Raynaud's phenomenon, irritable bowel disease, and heat and cold intolerance) can be associated with this condition. A careful differential diagnosis is mandatory: fibromyalgia is not a diagnosis of exclusion. Since 1990, diagnosis has been principally based on the two major diagnostic criteria defined by the ACR. Recently, new criteria have been proposed. The main goals of the treatment are to alleviate pain, increase restorative sleep, and improve physical function. A multidisciplinary approach is optimal. While most nonsteroidal anti-inflammatory drugs and opioids have limited benefit, an important role is played by antidepressants and neuromodulating antiepileptics: currently duloxetine (NNT for a 30% pain reduction 7.2), milnacipran (NNT 19), and pregabalin (NNT 8.6) are the only drugs approved by the US Food and Drug Administration for the treatment of fibromyalgia. In addition, nonpharmacological treatments should be associated with drug therapy.
Available from: Irwin Jon Russell
Available from: Anna Ericsson
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