Background/Purpose: The majority of patients with PsA have psoriasis prior to arthritis and there is evidence that a significant proportion of patients in dermatology clinics have undiagnosed PsA.  Multiple screening questionnaires have been developed and tested for the early detection of PsA but there has been no direct comparison to identify which is the optimal screening questionnaire. The aim of this study was to compare three existing PsA screening questionnaires (PASE, PEST, TOPAS) in a head-to-head study in secondary care dermatology clinics using the CASPAR criteria as the gold standard.

Methods: This study recruited from 10 UK secondary care dermatology clinics.  Patients with a diagnosis of psoriasis, not previously diagnosed as PsA, were given a pack containing study information, and all 3 questionnaires in a random order.  The completed questionnaires were compiled and scored by a study co-ordinator and all patients who were positive on any of the questionnaires were invited for a rheumatological assessment where consent was obtained.  This assessment included physical examination of joints, entheses, dactylitis, spine, skin and nails.  Where available, rheumatoid factor positivity and radiographic reports were collected. Receiver operator characteristic (ROC) curves were used to compare the sensitivity, specificity and area under the curve (AUC) of the 3 questionnaires with their diagnosis according to CASPAR criteria.

Results: In total, 938 patients with psoriasis were invited to participate and given a screening pack.  Of these, 657 (70%) patients returned the screening questionnaires.  One or more questionnaires were positive in 314 patients (48%) and these were invited for rheumatological assessment.  Of these positive patients, 119 (37%) declined to attend for examination, leaving 195 (63%) patients with positive questionnaires who were assessed. There were 47 patients diagnosed with PsA according to the CASPAR Criteria, equating to 24% of those with positive questionnaires who attended for examination.  The proportion of patients found to have PsA increased with the number of positive questionnaires (1 questionnaire = 19.1%, 2 questionnaires = 34.0%, 3 questionnaires = 46.8%).  Sensitivities and specificities for the three questionnaires are shown in the table below. A positive non-PsA diagnosis was made in 54 subjects: 40 of these had degenerative tendinopathy or osteoarthritis.

Questionnaire	Sensitivity	Specificity	AUC	P value
PASE	74.5	38.5	0.594	0.052
PEST	76.6	37.2	0.610	0.023
TOPAS	76.6	29.7	0.554	0.267

Conclusion: Both the PEST and TOPAS questionnaires performed slightly better than the PASE questionnaire at identifying PsA but discriminatory capacity overall was best for the PEST questionnaire.  As patients scoring negative for the questionnaires were not examined these results are likely to overestimate the sensitivity and underestimate the specificity. Nevertheless, these screening tools do identify many cases of musculoskeletal disease other than PsA.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/comparison-of-three-screening-tools-in-psoriatic-arthritis-the-contest-study/