Page 25 - Recognizing axial spondyloarthritis - Janneke de Winter

RESULTS
Patient characteristics and disease burden in axial SpA versus peripheral SpA
Of the 314 SpA patients fulfilling the ASAS criteria, 230 patients fulfilled the ASAS axial SpA criteria and 84 patients fulfilled the peripheral SpA criteria (73.2% vs. 26.8%)(Figure 1). The demographic and clinical characteristics of both patient groups are summarized in Table 1. The mean age of the ASAS axial SpA patients was 41 (33-52) compared to 48 (37-56) for the ASAS peripheral SpA patients (p=0.005). Of the 230 ASAS axial SpA patients, 145 were male, compared to 49 of the 84 ASAS peripheral SpA patients (63% vs. 58%, p=0.447). ASAS axial SpA patients had an earlier disease onset (32 (24-41) years) than ASAS peripheral SpA patients (38 (31-48) years, p=0.001). Of the 230 ASAS axial SpA patients, 170 were HLA-B27 positive, compared to 18 of the ASAS peripheral SpA patients (76% vs. 27%, p<0.001). All of the 230 ASAS axial SpA patients had present or past back pain, compared to 18 of the 84 ASAS peripheral SpA patients (only past back pain) (100% vs. 21%, p<0.001), and 161 of the 230 ASAS axSpA patients fulfilled the mNY criteria versus 0 of the 84 ASAS peripheral SpA patients (70% vs. 0%, p<0.0001). Arthritis (p<0.001), enthesitis (p<0.001) and dactylitis (p=0.009) were more frequent in ASAS peripheral SpA patients (Table 1), as were psoriasis (p<0.001) and IBD (p=0.004). In contrast, but in line with the frequency of HLA-B27, uveitis was more prevalent in axial SpA (p<0.001). A positive family history was observed in 86 of the ASAS axial SpA patients and in 23 of the ASAS peripheral SpA patients (37% vs. 27%, p=0.099).
Disease activity measurements specifically addressing axial disease were higher in ASAS axial SpA than in ASAS peripheral SpA patients, respectively, whereas CRP and ESR levels as markers of systemic inflammation were similar between both groups (Table 1). Interestingly, not only composite parameters originally developed for axial disease - such as BASDAI and ASDAS-CRP - but also parameters of global disease activity (patient’s and physician’s global assessment) were significantly higher in axial than peripheral SpA (p<0.001 for all 4 comparisons). This was still the case upon analysis of patients naive to TNF-α blocking therapy (data not shown).
As a reflection of standard clinical care, non-steroidal anti-inflammatory drug (NSAID) usage was higher and corticosteroid and csDMARD usage lower in the ASAS axial SpA group (all p<0.05)(Table 1). The use of TNF-α inhibitors did not differ between patients fulfilling the ASAS axial vs. peripheral SpA criteria.
Patients with purely axial and combined axial and peripheral SpA
The ASAS criteria exclude patients with active axial symptoms from the peripheral SpA group but do not exclude patients with active peripheral symptoms from the axial SpA group. Our results show that peripheral arthritis as well as enthesitis occurred each in more than 30% of the patients with axial SpA (Table 1). Therefore, we additionally differentiated the 230 patients fulfilling the ASAS axial SpA
PERIPHERAL DISEASE IN AXIAL SPA
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