Page 26 - Recognizing axial spondyloarthritis - Janneke de Winter

CHAPTER TWO
criteria into purely axial disease (without concomitant arthritis, enthesitis, and/ or dactylitis) (n=112, 48.7%) and combined disease (axial SpA with concomitant arthritis, enthesitis or dactylitis) (n=118, 51.3%) (Figure 1). Table 2 shows the characteristics of patients with purely axial SpA and combined axial and peripheral SpA.
The mean age of the patients with purely axial SpA patients was 39 (32-48) compared to 44 (34-54) for the patients with combined SpA (p=0.064). Seventy of the 112 patients with purely axial SpA were male, compared to 75 of the patients with combined SpA (63% vs. 64%, p=0.868). The patients with purely axial SpA had a mean disease onset at 32 (23-38) years, patients with combined SpA at 34 (24- 44) years. Of the 112 patients with purely axial disease, 86 were HLA-B27 positive, compared to 84 of the patients with combined SpA (80% vs. 72%, p=0.163).
By definition none of the 112 patients with purely axial SpA had peripheral arthritis, enthesitis or dactylitis, of the patients with combined SpA, 75, 73 and 9 patients had peripheral arthritis, enthesitis or dactylitis, respectively (p=<0.001, p=<0.001 and p=0.003). Of the 112 patients with purely axial SpA, 7 had psoriasis and of the patients with combined SpA 16 had psoriasis (6% vs. 14%, p=0.065). Seven of the 112 patients with purely axial SpA had IBD, compared to 7 of the 118 patients with combined SpA (p=0.920). Of the patients with purely axial SpA, 41 had a positive family history for SpA, compared to 45 of the patients with combined SpA (37% vs. 45%, p=0.811).
The median Patient’s global assessment was 52 (23-68) in patients with purely axial SpA and 61 (45-75) in patients with combined SpA (p=0.0010). The median Physician’s global assessment in patients with purely axial SpA was 44 (16-60) compared to 53 (33-62) in combined SpA (p=0.009). The median BASDAI was 4.4 (2.9-6.0) in patients with purely axial SpA and 5.4 (4.0-6.6) in patients with combined SpA (p=0.001). The median ASDAS-CRP level was 2.6 (1.8-3.5) in the patients with purely axial SpA and 3.0 (2.2-3.7) in patients with combined SpA (p=0.014). There was no significant difference in CRP and ESR levels. The group with combined axial and peripheral disease retained the highest disease activity after exclusion of patients treated with anti-TNF therapy (data not shown). Of the 112 patients with purely axial SpA, 5 used any csDMARD, compared to 27 of the patients with combined disease (5% vs. 23%, p=<0.001).
Peripheral disease in combined axial versus peripheral SpA
To further assess the potential relevance of peripheral disease in the group of ASAS axial SpA, we compared peripheral disease features and treatments between combined SpA and peripheral SpA. Patients with combined SpA had a higher prevalence of enthesitis than patients with peripheral SpA (62% vs. 48%, p=0.044) but a lower prevalence of peripheral arthritis (63% vs. 98%, p<0.001). Dactylitis prevalence was not different between both groups. Prevalence of psoriasis and IBD was higher in patients with peripheral SpA (54% vs. 14%, p<0.001 and 17% vs. 6%, p=0.014, respectively) while uveitis prevalence was higher in patients with
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