Page 31 - Recognizing axial spondyloarthritis - Janneke de Winter

the real phenotype of the patients. In the Leiden early arthritis cohort the ASAS peripheral SpA criteria were applied on early arthritis patients with past and/or present IBP (39) while strictly speaking the ASAS axial SpA criteria should always be applied in case of active IBP and not the peripheral SpA criteria. The COSPA (Cochin SpondyloArthritis study) cohort of established SpA used either the ASAS axial or peripheral SpA criteria based on what the predominant manifestation was according to the treating physician (40). A study analyzing the performance of the ASAS criteria in early SpA within the ESPERANZA program applied the axial SpA criteria only in patients with exclusively back pain and the peripheral SpA only on patients with peripheral arthritis, dactylitis or enthesitis in the absence of axial pain (41), which is also not in line with the ASAS classification criteria. Another study assessing the prevalence of SpA in southern Sweden concluded that 57% fulfilled the ASAS classification criteria for peripheral SpA, 91% the ASAS classification criteria for axial SpA, and that 45% of this latter group also fulfilled the ASAS criteria for peripheral SpA (42), while according to the ASAS criteria it is not possible to fulfill both criteria arms. Finally, in our recent proof-of-concept clinical trial with adalimumab in non-AS, non-PsA peripheral SpA according to the ESSG criteria post-hoc application revealed that 38/40 patients would fulfill the ASAS criteria for peripheral SpA if not taking into account that 22/40 patients also had active IBP when actively questioned for axial complaints (34). Therefore, it could theoretically be considered to use the ASAS criteria differently and either classify patient according to the major disease manifestations (rather than use axial SpA as default setting) or to classify them as axial SpA, peripheral SpA, or axial and peripheral SpA.
The key question, however, is if merely changing the criteria would impact recognition and treatment of peripheral disease in clinical practice? It may be more relevant to maintain the current classification but clarify in management and treatment guidelines how this should be applied. Careful evaluation and monitoring of peripheral disease (and similarly: extra-articular manifestations and co-morbidities) remains needed in all SpA patients, even in the axial SpA subset. And treatment decisions should be based not only on axial disease targets and/ or peripheral disease targets, but should include composite indices and/or PRO’s reflecting the global disease burden where appropriate (6,43). An example of such an approach is the Minimal Disease Activity (MDA) in psoriatic arthritis, which includes different domains of the disease (44,45). Interestingly, we previously demonstrated that both BASDAI and ASDAS perform well in peripheral SpA (46). Therefore, it would be relevant to evaluate in a real-life study if systematic use of these tools to monitor disease activity and guide treatment decisions– not only for axial SpA but also for combined axial and peripheral SpA- may favorably impact outcome in not only purely axial SpA but also combined axial and peripheral SpA.
PERIPHERAL DISEASE IN AXIAL SPA
29
TWO