Background/Purpose

Patients with Non-Radiographic Axial Spondylarthritis (non-Rx AxSpA) don’t presnt with different clinical manifestations than patients with Ankilosing Spondylitis (AS), although the inflammatory burden measured by ASDAS and CPR is higher in the latter.  Stydies have still yet to discover any difference in inflammatory burden between patients with non-Rx SpA classified by ASAS criteria by the pathway of imaging (active inflammatory lesions in sacroiliac joints detected by MRI) and that classified by the clinical pathway (HLA-B27). The aim of this study is to analyze the clinical characteristics and the inflammatory burden of patients classified of Axial Spondylorarthritis (AxSpA) by ASAS criteria attended in recent-onset Spondyloarthritis Unit (RSpAU).

Methods

We included adult patients younger than 45 years old attended the RSpAU of the General Hospital in Mérida (Spain) between May 2008 and May 2014 with inflammatory low back pain more than 3 months and less than 2 years, asymmetric arthritis and/or mechanical low back pain/arthralgias accompanied by , at least, one of the following: psoriasis, uveitis, inflammatory bowel disease (IBD), entesytis, sacroiliitis on imaging, HLA-B27(+) or familiy history of SpA. Patients with previous diagnosis of SpA were however excluded.

Results

We studied 132 patients, 36 patients fulfilled ASAS criteria for SpA. Of this group, 8 patients fulfilled NY criteria for EA, and 28 were diagnosed with non-Rx SpA. Of the patients with non-Rx SpA, 16 entered through the clinical pathway (HLA-B27) and 12 through the pathway of imaging (MRI of sacroiliac joints with active inflammatory lesions or bone marrow edema). The age at the diagnosis was 29.5 year for both EA and non-Rx SpA. In the group of non-Rx SpA  we found female predominance (16 women/12 men), in particular in the group with MRI positive and HLA-B27 negative (4 women/2 men). The measures of BASDAI and BASFI indexes were higher in the group of non-Rx SpA, but without  stadistically significance. In patients with non-Rx SpA, the medium level of CRP was higher in patients with positive MRI than patients that entered by the clinical pathway, but without sadistically significance.

Conclusion

In the non-Rx SpA there is a female predominance and a lower rate of HLA B27 (+) than in radiological EA. We didn’t find any significant differences in the indexes used to measure the inflammatory burden between both groups. There is a trend to higher inflammatory burden measured by CRP and ASDAS in EA than in non-Rx SpA and in the last group, higher in patients with active inflammatory lesions in sacroiliac joints by MRI.

	nº	H:M	B27+ %	BASDAI Media 95%IC	ASDAS Media 95%IC	BASFI Media 95%IC	EGP Media 95%IC	PCR (mg/L) Media 95%IC
TOTAL	36	0,80	83,33	4,95 (4.26,5.64)	2,83 (2.46,3.20)	2,81 (1.97,3.65)	6,11 (5.2,7.02)	9,02 (3.61,14.43)
AS (NY)	8	1,6	100	4,25 (2.49,6.01)	2,95 (1.72,4.18)	2,425 (0.44,4.40)	5,75 (3.25,8.25)	21,01 (0,43.32)
non-Rx AxSpA	28	0,75	78,6	5,18 (4.40,5,96)	2,8 (2.43,3.31)	2,92 (1.95,3.89)	6,21 (5.21,7.21)	5,61 (2.31,8.91)
HLAB27	16	0,77	100	5,01 (3.86,6.16)	2,72 (2.21,3.23)	2,75 (1.47,4.03)	6,25 (4.86,7.64)	4,87 (0.51,9.23)
RMN	12	0,71	50	5,42 (4.3,6.54)	2,91 (2.3,3.52)	3,14 (1.48,5.80)	6,17 (4.53,7.81)	6,61 (1.12, 12.20)

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/inflammatory-burden-in-recent-onset-axial-spondyloarthritis/