Background/Purpose: Psoriasis (Pso) is one of the most common chronic inflammatory skin disease in Europe. Psoriatic arthritis (PsA) is closely associated to Pso; the skin manifestation appears usually years before PsA-related symptoms emerge. Up to 30% of Pso patients develop PsA; its concrete prevalence is still unclear. Questionnaires for detection of PsA (PASE, PEST, GEPARD) are validated tools for use in dermatology practice with different sensitivity and specificity levels. Fluorescence-optical imaging technique is a new method to detect changes in microvascularisation of the hands as potential early marker for subclinical musculoskeletal inflammation.

Methods: This interims analysis includes 150 Pso patients (diagnosis confirmed by dermatologist) without pre-existing diagnosis of PsA but risk factors for its development (nail psoriasis and/or joint pain or swelling within the last 6 months) from a prospective, multicentre study (XCITING) in Germany. Patients are examined by rheumatologist (clinical examination and ultrasound) to determine PsA-diagnosis. FOI is performed in addition to standard examinations and analysed by an independent experienced reader. The results for PASE, PEST and GEPARD questionnaires as well as for FOI in comparison to the diagnosis of PsA by rheumatologist are compared to survey their sensitivity, specificity and their positive and negative predictive values for detection of PsA.

Results: In 46.4 % of the Pso patients with risk of development of PsA (as defined in inclusion criteria) PsA was diagnosed by rheumatologist using clinical examination and ultrasound. For detection of PsA, PASE questionnaire had a sensitivity of 44.3% and a specificity of 64.2% whereas its positive predictive value was 51.7%, its negative predictive value 57.1%, respectively. Sensitivity of PEST was calculated with a value of 12.9% whereas its specificity was 80.3%; its positive predictive value was 36%, its negative predictive value 51.6%. GEPARD had a sensitivity of 64.3% and a specificity of 38.3% for detection of PsA. Its positive predictive value was 47.4%, its negative predictive value 55.4%. FOI had a specificity of 27.2% and a sensitivity of 51.4%. Its positive predictive value was 37.9%, its negative predictive value 39.3%, respectively.

Conclusion: In this cohort of patients with active Pso and risk of development of PsA, more than 40% of the patients were classified as PsA by rheumatologist using clinical examination and ultrasound. The highest positive and negative predictive values for detection of PsA were detected for use of PASE questionnaire. FOI as new imaging marker had low specificity but marked sensitivity for detection of PsA compared to the questionnaires keeping in mind that only the hands are captured with the device; FOI reached positive and negative predictive values of 37.9 and 39.3%, respectively. For use in clinical routine care, combination of both, FOI and questionnaires might be useful for sufficient PsA diagnosis and exclusion or diagnosis of other types of arthritides of the hands that might be distinguished by use of FOI.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/predictive-value-of-different-tools-for-detection-of-psoriatic-arthritis-in-patients-with-psoriasis-in-daily-routine-care-using-questionnaires-for-diagnosis-of-psoriatic-arthritis-and-fluorescence-opt/