Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.

Identification of the Clinical Features That Can Distinguish between Psoriatic Polyenthesitis and Fibromyalgia.

Marchesoni6,  Antonio, Varisco6,  Valentina, Atzeni7,  Fabiola, Spadaro3,  Antonio, Lubrano5,  Ennio, D'Angelo10,  Salvatore, Cauli4,  Alberto

AOUC University of Florence, Italy
San Carlo Hospital of Potenza, Italy
CTO Hospital, Palermo, Italy
Department of Clinical and Medical Therapy, Sapienza-University of Rome, Italy
Department of Medical Sciences, University of Cagliari, Italy
Fondazione Maugeri, IRCCS, Telese Terme, Italy
G.Pini Orthopedic Institute, Milan, Italy
L. Sacco University Hospital, Milan, Italy
Reggio Emilia Hospital, Italy
Rheumatology Research Unit, University Federico II Naples, Italy

Background and Purpose:

As polyenthesitic psoriatic arthritis (PsA) is sometimes hard to distinguish from fibromyalgia (FM), secondary FM in PsA patients and PsA in FM patients can be misdiagnosed. The purpose of this study was to identify which clinical features can help distinguish between polyenthesitic PsA and FM.

Materials and Methods:

This was a multicentre cross-sectional study carried out by 10 Italian tertiary Rheumatologic (8 recruiting PsA patients and 2 FM patients) centres from January 2009 to September 2009. All of the consecutives patients with PsA (CASPAR criteria) and FM (ACR criteria) who accepted to participate to the study were enrolled in it. For each patient all of the standard clinical and laboratory data, including the questionnaires for PsA and FM, were collected. For the statistical analysis, Student's t test, c2 test, Fisher's exact test, univariate and multivariate logistic regression, and Receiving Operating Characteristic (ROC) curves, were used as appropriate.


Two-hundred-sixty-two PsA patients (122 females and 140 males, mean age 51.9±12.8, mean disease duration 10.1±9.2 years) and 96 FM patients (89 females and 7 males, mean age 50.6±1.8, mean disease duration 5.4±4.1 years) were enrolled in this study. Eighteen (6.9%) PsA patients met the classification criteria for FM. Tender and swollen joint counts, dactylitis count, ESR and CRP, and response to NSAIDs were significantly higher in the PsA group. Inflammatory back pain, HAQ values, and PtGA scores were comparable in the two groups. Enthesitis score, tender point count, morning stiffness, VAS pain by patient, and all of the typical symptoms of FM (headache, irritable bowel syndrome, sleep disturbances, paresthesias, anxiety, depression, Raynaud's phenomenon) were significantly associated with FM. However, using the univariate logistic regression, the ORs of morning stiffness, anxiety, and depression were not statistically different between the two groups. The ROC curves showed that 6 or more FM-associated symptoms (sens. 93%, spec. 86%) and 8 ore more tender points (sens. 93%, SPEC 82%) had the best performance in identifying FM patients. The multivariate logistic regression (table 1) showed that 6 or more FM-associated symptoms, 8 or more tender points, and no response to NSAIDs were significantly predictive of FM.


Number of FM-associated symptoms, number of tender points, and response to NSAID can help distinguish between polyenthesitic PsA and FM.

Table 1. Multivariate logistic regression of the main features associated with FM

FeatureOR95% ICp
Female gender0.880.23–3.400.853
VAS pain1.000.97–1.020.798
FM symptoms >=620.057.15–56.230.000
Enthesitis score >=30.530.20–1.440.212
Tender points >=816.494.62–58.860.000
No response to NSAIDs6.371.52–26.710.011

To cite this abstract, please use the following information:
Marchesoni, Antonio, Varisco, Valentina, Atzeni, Fabiola, Spadaro, Antonio, Lubrano, Ennio, D'Angelo, Salvatore, et al; Identification of the Clinical Features That Can Distinguish between Psoriatic Polyenthesitis and Fibromyalgia. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :532
DOI: 10.1002/art.28301

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