Background The mNY criteria1, which indicate sacroiliitis of at least grade 2 bilaterally or grade 3 or 4 unilaterally, are used to classify patients (pts) as Ankylosing Spondylitis (AS). However, little is known about the occurrence of syndesmophytes in the spine in the absence of radiographic sacroiliitis.
Objectives To investigate if syndesmophytes are prevalent in pts with chronic back pain suspected of axSpA who are not fulfilling the mNY criteria and if syndesmophytes should be included to define pts as having radiographic axSpA.
Methods Pts with back pain (≥3 months, ≤2 years, onset ≤45 years) recruited from 5 participating centres across Europe were included in the SPondyloArthritis Caught Early (SPACE)-cohort. All patients underwent conventional radiographs of the cervical and lumbar spine and sacroiliac (SI)-joints (X-spine and X-SI, respectively). X-spine was scored on the presence or absence of ≥1 syndesmophyte, X-SI was scored according to the mNY1. X-rays were scored independently by 3 readers. Lesions were considered present if 2/3 readers agreed.
Results All pts with both X-spine and X-SI data available (n=302) were used for comparison. There were 26 pts (8.6%) fulfilling the mNY criteria and 7 pts (2.3%) with ≥1 syndesmophyte present in the spine. None of those 7 pts showed radiographic sacroiliitis nor active lesions on MRI of the SI joints. Two pts fulfil the ASAS axSpA criteria and 5 had SpA features but did not fulfil the criteria. In table 1 the number and location of syndesmophytes and SpA features are presented. Most pts (n=5) had 1 syndesmophyte. The two pts with >1 syndesmophyte did not fulfil the ASAS axSpA criteria. All pts had syndesmophytes located solely in the cervical part of the spine. Only 2/302 (0.7%) pts would be considered as having signs of radiographic axSpA if syndesmophytes (in absence of radiographic sacroiliitis) would be considered a sign of radiographic involvement.
Conclusions In this population, syndesmophytes in pts without sacroiliitis on radiographs and MRI are infrequent and solely located in the cervical spine. Indicating that syndesmophytes are not informative in classifying pts as having radiographic axSpA in early disiease.
van der Linden S A&R 984;27:361–8
Disclosure of Interest None Declared