Axial Involvement in Psoriatic Arthritis LUMC

Involvement of the axial skeleton (of sacroiliac joints and / or spine) is one
of the relatively frequent manifestations associated with psoriatic skin
disease along with involvement of peripheral musculoskeletal structures
(peripheral arthritis, enthesitis, dactylitis), which are usually referred to
as psoriatic arthritis (PsA). Data from cohort studies suggest that up to 30%
of patients with psoriasis develop PsA. Depending on the definition used, the
prevalence of axial disease varies from 25% to 70% of patients with PsA. Recent
data from the CORRONA registry indicated that the presence of axial involvement
is associated with a higher likelihood of moderate/severe psoriasis, with
higher disease activity and greater effect on quality of life in patients with
PsA.
There is an ongoing discussion as to whether patients with psoriasis and
inflammatory axial disease should be diagnosed with *PsA with axial
involvement* (other commonly used terms: psoriatic spondylitis, psoriatic
spondyloarthritis, axial PsA) or with *axial spondyloarthritis with psoriasis*.
Although some features typical for axial involvement in PsA have been described
(such as asymmetry of inflammatory changes, lower - as compared to the primary
axial spondyloarthritis without psoriasis - prevalence of inflammatory back
pain and HLA-B27, involvement of the spine without sacroiliac joints), a clear
distinction is not always possible due to a natural overlap between these
conditions. There is also an overlap between the CASPAR (ClASsification
criteria for Psoriatic ARthritis) classification criteria for PsA and ASAS
(Assessment of Spondyloarthritis international Society) classification criteria
for spondyloarthritis - SpA (both axial and peripheral) resulting from the
pathophysiological proximity of the diseases. Currently, there is no clear and
widely accepted definition of axial involvement in PsA. Patients with PsA can
be classified as patients with axial SpA in the presence of chronic back pain
with onset prior to the age of 45 years plus presence of sacroiliitis on
magnetic resonance imaging (MRI) or Radiographs (plus one additional SpA
feature that can be psoriasis), or alternatively in the presence of HLA-B27
plus 2 additional SpA features. Data from a recent systematic literature
suggested that PsA patients with axial involvement frequently have
characteristics that would not allow classification of patients as axial SpA
such as late onset of back pain, involvement of the spine without sacroiliac
joints, weaker association with HLA-B27, less frequent inflammatory character
of back pain. Furthermore, it is currently unclear if treatment response in PsA
patients with axial involvement can be extrapolated from the data generated in
primary axial SpA since only a few studies have been conducted so far in
patients with PsA and
(suspected) axial involvement. For example, in primary axial SpA two
interleukin-23 inhibitors (ustekinumab and risankizumab) failed to show
clinical efficacy compared to placebo, despite good clinical efficacy in
psoriasis and PsA with predominant peripheral involvement. There is a need to
determine whether these drugs, as well as other drugs that have shown efficacy
in peripheral manifestations of PsA are also effective in the axial component
of PsA.
In general, axial involvement is poorly assessed (or not assessed at all) in
trials with PsA. The main reason for this is the lack of a widely accepted
definition of axial involvement in PsA that could be used for research
purposes. Since axial involvement may be quite variable and often not present,
it has been difficult to justify the added measurement burden and expense of
longitudinal MRI assessment of the spine and sacroiliac joints in the whole
study population or even in those with presumed axial involvement, which may
vary between study arms. There is an urgent need for criteria and a unified
and widely accepted nomenclature for axial involvement in PsA that would allow
defining a homogeneous subgroup of patients in the heterogeneous PsA population.
In 2018, ASAS and GRAPPA (Group for Research and Assessment of Psoriasis and
Psoriatic Arthritis) agreed to develop a consensus definition of axial
involvement in PsA to be used for research purposes. In addition to the
conducted systematic literature review, an online survey among ASAS and GRAPPA
members was conducted in Dec 2018 - Jan 2019 to identify the most relevant
variables relevant to deciding on the absence or presence of axial involvement
in PsA. The four variables with the highest ranking were related to the
objective signs of inflammatory changes in the axial skeleton on Radiographs or
MRI.
Currently, there is no PsA cohort in which a complete set of imaging (plain
radiographs and MRI of sacroiliac joints and spine) is available in all
patients. Therefore, we propose developing a prospective cross-sectional cohort
through which classification criteria for axial involvement in PsA can be
derived.

The overarching aim of the Axial Involvement in Psoriatic Arthritis (AXIS)
study is to systematically evaluate clinical and imaging manifestations
indicative of axial involvement in patients with PsA to develop classification
criteria and a unified nomenclature for axial involvement in PsA that would
allow defining a homogeneous subgroup of patients for research.

The main objectives of the planned study are:

1) To determine the frequency of axial involvement in patients with PsA (based
on the local and central assessments) in the studied patient population;

2) To identify the frequency of active inflammatory and structural changes on
imaging (on MRI and Radiographs) suggestive of inflammatory involvement of
axial skeleton (sacroiliac joints and spine) in PsA;

3) To identify factors (clinical, lab, imaging) associated with the presence of
axial involvement in PsA (determined based on the local and central
assessment).

This is a cross-sectional study in patients with a definite diagnosis of PsA.
Eligible patients will be recruited prospectively and will undergo
study-related examinations including imaging (radiography and MRI) of the axial
skeleton. These images will be evaluated locally and by the central imaging
committee. Collected data will serve as a basis for the determination of the
presence of axial involvement by the local investigator.
patiënts will be asked to come to a research visit, during which a physical
examination is performed, a MRI scan is made and the patient will be asked to
fill out several questionnaires. 2 sequences of the MRI scan are considered
coventional treatment, whereas 2 other extra sequences are part of the study.

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