Background According to official Russian Federation statistics the mean annual incidence of psoriatic arthritis (PsA) in patients (pts) with psoriasis (PsO) is 2.5%. Lower estimates may reflect a missed diagnosis of PsA. The efficiency of PsA screening approach in PsO pts in Russian dermatological clinics remains unknown.
Objectives to evaluate the prevalence and misdianosis of PsA in PsO pts in dermatological clinics according to the PEST questionnaire, rheumatological evaluation and the CASPAR criteria.
Methods 103 consecitive unselected pts (male-47/female-56) with plaque PsO mean age 44±13.69 years (yrs.), BSA 9.32±13.55%, PASI 15.39 ± 12.51, DQLI 9.42±6.8 with no known diagnosis of inflammatory arthritis were included. All pts completed the PEST questionnaire before being consulted by a dermatologist. A total score PEST≥3 is indicative of PsA, PEST<3 is non-PsA. All pts were subsequently evaluated by a rheumatologist to confirm/exclude PsA. The CASPAR criteria are considered to be the “gold standard” for the diagnosis of PsA. The sensitivity (Sen.) and the specificity (Sp.) of the PEST, (%) were calculated.
Results 60 out of 103 pts (58.2%) had PEST≥3 but after rheumatological assessment according to the CASPAR criteria PsA confirmed in significantly fewer cases – in 47 out of 60 pts (78.3%) and in 13 out of 60 pts (21.6%) PsA was overdiagnosed (false-positive). 43 out of 103 pts (63.4%) had PEST<3 but even so in 14 out of 43 pts (32.5%) PsA was undiagnosed and then confirmed after rheumatological assessment according to the CASPAR criteria (false-negative). So finally the prevalence of PsA in a series of 103 plaque PsO pts was 59.2% (61 pts). PsA was misdiagnosed in 27 out of 103 pts (26.2%). PEST Sen./Sp. were 77%/69% accordingly.
Conclusions In dermatological clinics the PEST questionnaire is a proper approach that is available for PsA screening. But PEST alone is limited due to high amounts of misdiagnoses. All pts should follow up with a rheumatologist and the CASPAR criteria despite the PEST results. For proper diagnosis of PsA among PsO pts need interdisciplinary collaboration with rheumatologists.
Disclosure of Interest None declared