Page 150 - Recognizing axial spondyloarthritis - Janneke de Winter

CHAPTER NINE
effects, while this is a surrealistic scenario. Third, we should emphasize that by treating at-risk individuals we will presumably also treat individuals that otherwise would not have gained axial SpA. To minimize this side effect, initiatives as the Pre-SpA cohort will first have to define precisely those individuals at sufficient increased risk to justify treatment or follow-up.
Concluding remarks and future directions
In the past decade, major progress has been made in the recognition of the disease burden, the recognition of the diagnosis and the recognition of the very early ore even pre-clinical phase of axial SpA.
Concerning the recognition of the disease burden in axial SpA, the focus has shifted from only the radiographic subtype (ankylosing spondylitis, AS) towards axial SpA, including other and early phenotypic expressions of the disease. The broad implementation of the classification criteria by the ASAS reflect that development (43), criteria that indicate the close resemblance of different SpA subtypes.
Increasing evidence exists that the early, non-radiographic form of axial SpA and the radiographic subtype are similar, at least from a phenotypical point of view. Furthermore, peripheral and extra-articular manifestations very frequently occur in axSpA, causing a significant burden of disease. Clinical studies should therefore not only focus on the treatment of axial disease, but also on the effects of treatment on peripheral and extra-articular disease.
Recognizing an axial SpA diagnosis early in the disease course is an aim that is worthy to achieve and challenging at the same time.
Worthy to achieve, since the current diagnostic delay of more than 5 years calls for improvement. Axial SpA has a significant burden of disease, already in its early phase. And although not robustly proven, studies indicate that treating axial SpA early in the disease course modifies the disease course and limits structural damage. Referral strategies for early back pain patients (33,44–46) have proven useful in detecting axial SpA in an early phase, and initiatives as the SPACE (47), GESPIC, PreSpA and DESIR cohort (48) all aim to diagnose axial SpA in an earlier phase and to study the early phase of the disease.
The recognition of early axial SpA challenges today’s clinician, since 1) Robust diagnostic biomarkers solely confirming a diagnosis of axial SpA are lacking. And, to date, investigations of serum biomarkers have not yet resulted in reliable diagnostic tools. Our finding that HLA-C*07 absence is associated with axSpA could aid the diagnostic process. The value of HLA-C*07 in the diagnostic process needs to be confirmed in other, larger cohort studies, thereby able to control for a possible linkage disequilibrium with HLA-B*27. Testing HLA-C*07 prevalence in an early setting as the inception cohort Pre-SpA might help to define individuals at increased risk to develop axial SpA. In the search after specific and sensitive biomarkers, the availability of large and well-documented early and preclinical SpA
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