Psoriatic arthritis classification criteria: Moll and Wright, ESSG and CASPAR -- a comparative study

to evaluate and compare Moll and Wright, ESSG and CASPAR criteria for psoriatic arthritis (PsA) classification.

Study comprised 356 patients (pts): 120 PsA pts in the investigated group, 123 pts with rheumatoid arthritis (RA) and 113 pts with non-inflammatory musculoskeletal symptoms (NIMS) in two control groups. Clinical diagnosis was the gold standard. Moll and Wright, ESSG and CASPAR criteria were applied to all pts. Sensitivity was calculated for each of the classification criteria sets; specificity was assessed in relation to RA and to NIMS groups, separately. Concordance between the investigated criteria sets was determined.

Sensitivity was 91.7% for CASPAR, 85.8% for Moll and Wright and 63.3% for ESSG criteria. Specificity for Moll and Wright criteria was 100%, with relation to both RA and to NIMS group. Specificity of CASPAR criteria was 99.2% and 99.1%; specificity of ESSG criteria was 94.3% and 67%, with regard to RA and to NIMS groups, respectively. Significant fair concordance was found only between CASPAR and Moll and Wright criteria (k=0.379 p<0.001).

The highest sensitivity had the CASPAR criteria, followed by Moll and Wright and ESSG. The highest specificity showed Moll and Wright criteria, followed by CASPAR and ESSG. CASPAR criteria demonstrated high specificity when applied to both NIMS and RA group. The lowest specificity was found for the ESSG criteria in relation to NIMS group. The only significant concordance was shown between CASPAR and Moll and Wright criteria.