Background Over 25% of the new consultations in primary care is due to musculoskeletal complaints (MSC)(1). In patient with psoriasis, the underlying diagnosis could be psoriatic arthritis (PsA). Prevalence figures of PsA in psoriasis patients vary widely (6-42%) and data in primary care is scarce (2, 3)
Objectives To estimate the prevalence of MSC and PsA in primary care patients with psoriasis.
Methods We conducted a cross-sectional study in adult primary care patients with psoriasis. Patients were identified from GP records by ICPC code S91 for psoriasis. Responding patients reporting pain in joints, entheses or the lower back were checked on eligibility by a telephone interview and invited for clinical evaluation. Ultrasonoghraphy (US) of the enthesis was performed if a patient had at least one tender enthesis (LEI/MASES) by an independent trained examiner. Patients were referred to a rheumatologist if clinical evaluation suggested the presence of arthritis or axial disease or ultrasonography of the enthesis showed positive Power Doppler (PD) signal. A PsA case was defined by opinion of the rheumatologist or fulfilling the CASPAR criteria with PD signal in an enthesis on US.
Results 2564 psoriasis (PsO) patients from 97 GPs were invited. Of the 1673 responders (65.2%), 841 (50.3%) were willing to participate. 823 (32.1%) patients reported suffering from MSC of which eventually 524 were eligible and clinically evaluated. We identified 81 cases of PsA (Figure 1), of which 17 (21%) were newly diagnosed, leading to a prevalence of 3.2% (95%CI 2.5%>3.9%) among primary care psoriasis patients, assuming no additional cases of PsA among the non-responders. Besides these cases, we also identified 36 patients with enthesitis confirmed by ultrasound, which would increase the prevalence of PsA towards 4.6% (95% CI 3.8%>5.4%).
Conclusions Among psoriasis patients in primary care the prevalence of PsA is estimated to be 3.2%, which would increase towards 4.6% if you take the enthesitis cases into account. Moreover, 21% of the cases was newly diagnosed. We hereby assumed that no additional cases would be observed in the non-responders. The prevalence of MSC is estimated to be 32.1%, which is comparable with the prevalence in general population (1).
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Gelfand JM. et al, Arch Dermatol. 2005
Acknowledgements This study was financially funded by an investigator-initiated grant from Pfizer bv.
Disclosure of Interest None declared