Resumen

VARELA, Paola et al. Role of periosteal new-bone formation in the performance of CASPAR diagnostic criteria for psoriatic arthritis. Rev.Colomb.Reumatol. [online]. 2014, vol.21, n.4, pp.169-176. ISSN 0121-8123.  https://doi.org/10.1016/j.rcreu.2014.07.002.

Objectives: To determine the changes in the diagnostic performance of the CASPAR criteria when a different radiological finding is included: the periosteal new bone formation (PoBF) in proximal or distal phalanges in conventional X-ray. Methods: A total of 72 patients with psoriasis were evaluated, of whom 25 had psoriatic arthritis (PsA). With the participation of one radiologist and one rheumatologist the interobserver agreement was calculated in order to assess the presence of PoBF. The sensitivity, specificity and predictive values were calculated for: juxta-articular new bone formation (JaBF), PoBF, CASPAR criteria, and CASPAR modified (CASPARm), which included the PoBF as radiological criteria. The reference standard for PsA diagnosis was the clinical judgment of the rheumatologist. Results: Therewas an 87% inter-observer agreement, with a Kappa of 0.56 with 95% CI: 0.311- 0.818. PoBF was the most frequent radiological finding in 24/25 compared to JaBF in 7/25 patients. In isolation PoBF had a better sensitivity but lower specificity for discriminating PsA than JaBF. There was no difference between the sensitivity and specificity of CASPAR vs. CASPARm. Conclusions: The PoBF in the CASPAR criteria may be useful for the classification of PsA. Because there is no difference in sensitivity, specificity and predictive values between CASPAR and CASPARm, the two set of criteria may be used in the diagnosis of psoriatic arthritis. Due to the high frequency of PoBF in patients with PsA and the little impact of this finding in the sensitivity and specificity, the weight given to radiological component in CASPAR criteria should be reassessed, allowing them to adapt better to the behavior of the disease in our environment.

Palabras clave : Psoriasis; Arthritic psoriasis; Periosteum; CASPAR criteria.

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