Can we improve the management of Juvenile PsA patients by using a different disease activity measure?

Juvenile Idiopathic Arthritis, (JIA) is the most common autoimmune disease in
children with inflammation of the joint (arthritis). JIA is a chronic
autoimmune disease of unknown cause, and disease onset is before the age of 16.
Different subtypes belong to this umbrella term. The combination of arthritis
with psoriasis is classified as Juvenile Psoriatic Arthritis (juv PsA).
According to the ILAR criteria, also children without psoriasis but having
arthritis in combination with at least two of the following symptoms belong to
the subtype juvenile PsA: dactylitis; nail pitting or onycholysis or psoriasis
in a first-degree relative.
Other subtypes of JIA are: systemic arthritis; oligo-articular subtype (1-4
joints), persistent and extended type; poly articular rheumatoid factor
negative and poly articular rheumatoid factor positive subtype and enthesitis
related type. The unclassified subtype of JIA, consists of patients who are
excluded from other subtypes.

To evaluate disease activity and effectiveness of (drug) treatment in pediatric
patients with children with psoriasis, several separate scoring methods for
skin and arthritis are in use. The most commonly used tools for arthritis are:
the ACR pedi composite score, which comprises the physician global assessment
of disease activity, parent/patient assessment of overall well-being,
functional ability, number of joints with active arthritis, number of joints
with limited range of motion; and erythrocyte sedimentation rate. A more
compact size, without functionality measurement and number of restricted joints
, is the Juvenile Arthritis Disease Activity Score (JADAS) (10-27-71 joints).
This tool consists of physician global assessment of disease activity,
parent/patient assessment of overall well-being, number of joints with active
arthritis; and the erythrocyte sedimentation rate or C-reactive protein. The
advantage of using one of these tools, is the ability to evaluate patients
burden (vas general well-being) as well as arthritis, which makes it possible
to compare with the other subtypes of JIA with juv PsA. Comparison between
subtypes might be important as up to 14% of the patients are reclassified to
another subtype during follow-up.

Skin involvement of (juvenile) psoriasis is an important marker for disease
activity, as this is one of the most important co-morbidities in young adults
with Juv PsA. Quantitative scoring of skin severity in dermatological oriented
literature includes calculation of the Psoriasis Area and Severity Index
(PASI). Other tools are the body surface area (BSA) and the Physician Global
Assessment. From all of these above mentioned scores, the PASI is recommended
in current consensus guidelines as the most thoroughly validated score and can
be recommended for quantitative evaluation of clinical severity of psoriasis.
Patient Reported Outcome Measurement tools (PROM*s) in pediatric psoriatic
patients are the Simplified Psoriasis Index (SPI) and the Dutch version of the
Children*s Dermatology Life Quality Index (CDLQI).
In addition to arthritis and skin involvement, other additional symptoms in
children with juv PsA are: enthesitis ( 30%), inflammatory bowel disease,
sacroiliitis or inflammatory low backpain (17%) and uveitis (11%). The presence
of psoriasis, sacroiliitis, and uveitis indicates a worse prognosis, as a
lower percentage of patients will remain a medication-free longterm remission.
In the majority of Juv PsA patients (50-70%), the disease is still active or
there are consequences of the disease in adulthood. This may be attributed to
under-treatment, as not all symptoms which are associated with juv PsA,
including the presence of enthesitis, dactylitis or nail-involvement, are
identified using currently validated disease activity tools.
In line with the recommendations of the World Health Organization (WHO), not
only disease related outcome, but also effect on functioning and participation
in daily practice are important to evaluate. These recommendations are
summarized in the International Classification of Functioning, Disability and
Health, commonly known as ICF framework. (ref International Classification of
Functioning, Disability and Health (ICF); www.who.int/classifications/icf/en/).
The relatively unfavorable prognosis of Juv PsA in functioning is described by
Scandinavian colleagues, where after long-term follow-up, lower scores on the
SF 36 (physical functioning) were found compared to oligo or poly articular
JIA.
In adult care, the various symptoms, seen in patients with PsA, are combined
into a composite measure, to evaluate disease activity, burden and effect of
treatment. Examples of these validated and internationally recommended
composite measures are the GRAPPA composite index and the PsA disease Activity
Score Index. Standardizing outcome measurement will improve the evaluation of
the effects of treatment and long term outcome.
However, to date, composite measures do not exist for juv PsA patients.

Due to the relatively high prevalence of PsA (1.5-2% in Northern Europe) and
the fact that psoriasis starts in childhood in about 25%, it is important to
develop adequate, preferably composite , validated disease activity scores, to
detect all symptoms that determine the prognosis and treatment of PsA., with
an early onset at childhood.

In this study, we would like to compare a composite disease activity tool with
the commonly used Juvenile Arthritis Disease Activity Score, in juvenile
patients with a probable or definite PsA.
Further on, we would like to investigate:
-which PsA specific symptoms are present in JIA patients
-to evaluate the burden of the disease
-idealiter, when follow-up of this cohort is possible, to evaluate the
characteristics and outcome of those patients who will develop definite Juv
PsA

Primary goal: to determine whether a combined disease activity measure
correlates better with disease burden than the current disease measure.

Primary study question: does the minimal disease activity JADAS (MDA-JADAS)
correspond to the MDA psoriasis?

Secondary:
-Mapping which PsA specific components are present in Juvenile Arthritis
patients.
-Burden of JIA, in specific Juvenile PsA, reflected in PROM*S

This is a cross sectional obseravtional study of patients diagnosed with
several subtypes of JIA, visiting the jongerenpoli (adolescent clinic) of the
department rheumatology of the Erasmus MC outpatient clinic. Patients
participating will have their regular clinical consult with the pediatric
rheumatologist (phvp) for observation of disease features, including PROM*s
(patient reported outcome measurements), physical examination, regular blood
testing and imaging when indicated. In addition patients will be investigated
for enthesitis using ultrasound. In case of (probable) involvement of skin and
nails, the (pediatric) dermatologist will be asked for consultation.

The disease activity parameters are obtained from the regular outpatient visit.
The questionnaires (PROMs) are currently regularly taken prior to the
outpatient visit. Completing the digital available questionnaires takes about
45-60 minutes. When patients are participating in the study, data necessary for
study purposes, data will be kept in an encrypted database. No specific
questions are asked for this study that could cause psychological or emotional
harm to the participant. For patients under the age of 18, in addition to the
consent of the patient, also consent of the parents/ legal guardians will be
requested. Evaluation of the enthesis by ultrasound will take approximately 30
minutes extra time.
In view of the above, the risk of damage to the participant is negligible.