CASPAR Criteria for Psoriatic Arthritis Adapt Well for Retrospective Use

The sensitivity, specificity, and feasibility of the ClASsification criteria for Psoriatic ARthritis (CASPAR) are maintained when they are adapted for retrospective use to classify an established research cohort from medical records. The sensitivity and specificity are similar to those in previous reports even when data points are missing.

Tillett and colleagues applied the CASPAR criteria to the records of 480 patients with psoriatic arthritis (PsA) and 100 consecutive controls who had inflammatory arthritis. The CASPAR criteria consist of confirmed inflammatory articular disease with at least 3 points from current psoriasis, a history or family history of psoriasis, dactylitis, rheumatoid factor (RF) negativity, and other factors. The CASPAR score was modified for retrospective use; "inflammation" and “current psoriasis” were scored if they had ever been confirmed in the clinic. An expert in PsA provided clinical diagnosis.

Of 456 physician diagnoses of PsA, 8 did not fulfill the CASPAR criteria. Only 1 had all the CASPAR data available. Another 7 had no radiographs or no RF tests performed to allow for complete assessment. Sensitivity was 99.7%, and specificity was 99.1%. There was excellent interrater reliability.

The authors noted that the criteria were found to be easy and practical to apply to case records.