Discovery of Arthritis in Psoriasis Patients for Early Rheumatological referral (DAPPER

Psoriasis (PsO) is a common inflammatory skin disease. Besides the skin, it is
recognized that this disease can affect multiple domains such as nails, joints
and entheses. About 30% of the patients with PsO will develop symptoms in the
musculoskeletal domains. Untreated inflammation in psoriatic arthritis (PsA)
can lead to irreversible joint damage and further reduces quality of life.
Since musculoskeletal involvement is often preceded by the dermatological
symptoms of PsO, patients with pure cutaneous psoriasis (PsC) should be
routinely screened for joint involvement. Current screening questionnaires,
like the often used Psoriasis Epidemiology Screening Tool (PEST), offer a
moderate discrimination between patients with PsA and PsC at best. Our aim is
to assert the prevalence of known and previously undiagnosed PsA in a PsC
cohort. By comparing the gathered data of the PsA and PsC patients, we hope to
improve the screening of PsC patients, and to reduce both undertreatment of
locomotor symptoms as well as unnecessary diagnostic investigations.

To ascertain the prevalence of PsA in a tertiary PsO cohort. Secondary
objectives will be to ascertain the clinical features of these patients. With
these features we want to find clinical, laboratory or genetic markers to
predict the presence of PsA in PsO patients. Moreover, we wish to establish the
added value of PsA screening for the quality of life (QoL) of PsO patients.

Cross-sectional study with a single follow-up visit after 1 year. Patients will
be screened at baseline for PsA symptoms by a rheumatology resident and
referred to a rheumatology clinic if deemed necessary. At baseline, several
clinical and sociodemographic parameters will be assessed. We will collect
blood samples for diverse biochemical studies and genomic DNA. Patients will be
followed for 1 year after active screening for PsA. Quality of life (QoL) and
treatment change will be recorded after this period, to assess the effect of
screening and referral.

Baseline screening visit will be performed following a planned usual care
outpatient visit. During the screening visit, an oral screening extensive
history taking and physical examination will be performed. Questionnaires
regarding screening (one) and QoL (three) will be taken. Blood samples will be
taken. If treated with systemic therapy, the blood sample can be combined with
regular laboratory tests needed for usual care. Patients with suspected PsA
will be referrred to the rheumatology clinic of the Sint Maartenskliniek for
confirmation of the diagnosis and regular care. After one year, clinical data
will be retrieved from both the dermatologic and rheumatic center. Patients
will be asked to re-evaluate their QoL. Risks associated with this study are
minor. The risk of clinically relevant accidental findings will be discussed
thoroughly during the informed consent.