The classification for psoriatic arthritis (CASPAR) criteria -- A retrospective feasibility, sensitivity, and specificity study

The Journal of Rheumatology, 11/28/2011

Tillett W et al. – This study demonstrates that the feasibility, specificity, and sensitivity of the CASPAR are maintained when adapted for retrospective use to classify an established research cohort.

Methods

  • 480 patient records were reviewed from the Royal National Hospital for Rheumatic Diseases Psoriatic Arthritis (PsA) cohort and for 100 consecutive controls with inflammatory arthritis from a general rheumatology clinic
  • The CASPAR score was modified for retrospective use; both “inflammation” and “current psoriasis” were recorded as present if they had ever been confirmed in the rheumatology clinic
  • Sensitivity and specificity of CASPAR criteria were compared with expert clinical diagnosis

Results

  • 480 database records were identified
  • 9 sets of records had been lost or destroyed
  • Diagnoses had changed in 15 cases, which were transferred to the control arm, leaving 456 patients with an expert diagnosis of PsA
  • Of 115 controls, 96 had RA, 5 OA, 3 reactive arthritis, 3 seronegative arthritis, 3 undifferentiated arthralgia, 2 ankylosing spondylitis, 1 spondyloarthritis, and 2 systemic sclerosis
  • Sensitivity (99.7%) and specificity (99.1%) were both high and equivalent to previous reports
  • Sensitivity remained high even after inclusion of 7 PsA patients with insufficient data to complete the CASPAR assessment (sensitivity 98.2%, specificity 99.1%)
  • Criteria were found to be easy and practical to apply to case records

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