Background Psoriatic Arthritis (PsA) is a progressive inflammatory joint disease that can lead to severe joint damage. New treatment strategies can be very effective in early stages of the disease . This requires early recognition of the symptoms to be PsA. Several screening tools have been developed to enhance early recognition [1-4]. However, most were developed in secondary care [2,3], while early recognition should ideally take place in primary care.
Objectives To evaluate the screening performance of the PEST , PASE [2,5] and EARP  to identify psoriatic arthritis among primary care psoriasis patients with recurrent spells musculoskeletal complaints (MSC).
Methods We conducted a cross-sectional study in adult primary care patients with psoriasis who reported recurrent MSC spells. Patients were selected by ICPC code S91 for psoriasis and the presence of recurrent spells of MSC (joints, enthesis or low back pain) was determined by telephone interview. Patients completed the PEST, PASE & EARP questionnaires before clinical evaluation by a trained research nurse. Assessments included PASI, LEI/MASES, 66/68-joint count and the presence of nail-psoriasis. When patients reported a painful enthesis on LEI/MASES, an ultrasound of the entheses was performed. A PsA case fulfilled the CASPAR criteria. Sensitivity and specificity were determined for the PEST and EARP cut off ≥3 and PASE cut off ≥44 as well as ≥47.
Results 473 psoriasis patients participated with a mean ± SD age of 55.7±13.9 years and 50.9% being male. Median PASI score was 2.3 (IQR 1-4) and 71 patients (15.0%) had nail abnormalities related to psoriasis. We found 17 new cases of PsA (3.6%) as diagnosed by a rheumatologist. Moreover, we found 36 cases of enthesitis, confirmed by ultrasound. The majority of these refrained from further evaluation by a rheumatologist, however most of them would classify as PsA according to the CASPAR criteria. Looking into all cases, including enthesitis, the EARP had a sensitivity of 87% and a specificity of 33%, for the PEST this was 68% and 71%. The PASE had a sensitivity of 66% and a specificity of 55% at the cut off of ≥44 and 59% and 64% at the cut off of≥47 (Table 2). Similar figures were observed if only axial manifestations and arthritis were taken into account.
Conclusions Modest sensitivity was observed for the PEST and PASE with an acceptable specificity for the PEST, while the EARP had high sensitivity and low specificity, which is undesirable for screening. The performance of all screening tools was lower than previously reported in secondary care settings [1-4].
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Acknowledgements This study was financially funded by an investigator-initiated grant from Pfizer bv.
Disclosure of Interest None declared