Psoriatic arthritis criteria evaluation: CASPAR and Modified CASPAR.

Sirs, Psoriatic arthritis (PsA) has been evaluated as a separate disease since 1964 by the American College of RheumatologyACR (1). The first and the simpliest Moll & Wright criteria (2) were followed by a number of classification criteria, but none of them survived enough to be widely used. CASPAR criteria (CIASsification criteria for Psoriatic Arthritis), are derived from a large international study, with reported sensitivity of 91.4% and specifity 98.7% (3). In order to improve the utility of the CASPAR criteria, Pederson et al. proposed the CASPAR criteria modification (Modified CASPAR criteria) (4) (Table I). Our study comprised 356 patients: 120 with PsA and two control groups, diagnostically consistent: 123 patients with rheumatoid arthritis (RA) and 113 with non-inflammatory musculosceletal symptoms (NIMS). Patients were taken consecutively from the hospital registry of the Rheumatology Institute, Belgrade in a three-year period. They were interviewed and examined according to the standard clinical protocol, including detailed anamnesis and physical examination recquired by the CASPAR and Modified CASPAR criteria. Every patient was examined independently by two experienced rheumatologists-clinicans. Psoriatic skin disease, psoriatic nail involvement and the entire digit involvement (dactilytis), was verified either at the time of examination, or documented previously in medical records by rheumatologist or dermatologist. Rheumatologists agreed upon each patient`s diagnosis in a meeting, and this was accepted as the gold standard. Sensitivity was calculated as percentage of PsA patients who satisfied, and specifity as percentage of RA or NIMS patients who did not satisfy the investigated criteria sets. CASPAR criteria were met by 110/120 patients with PsA and Modified CASPAR by 114/120 patients, so Modified CASPAR criteria showed advantage in sensitivity over the CASPAR (Fig. 1). Among those patients, 98.2% had psoriasis Two patients with PsA sine psoriasis (neither at the time of examination nor documented in personal anamnesis) met both CASPAR and Modified CASPAR criteria (both with negative RF, current dactylitis and juxta-articular new bone formation). CASPAR and Modified CASPAR criteria were not satisfied by six patients: five did not have psoriasis (neither at the time of examination, nor documented in personal history), and one had only examination-verified psoriasis. Four more patients with psoriasis documented in their personal anamnesis, but not at the time of examination (plus negative RF), satisfied Modified CASPAR, but not the CASPAR criteria (Table II). As for the control groups, one patient in CASPAR criteria (3)