Baseline and 1-year magnetic resonance imaging of the sacroiliac joint and lumbar spine in very early inflammatory back pain. Relationship between symptoms, HLA-B27 and disease extent and persistence.
BACKGROUND
The precise anatomical location of pathology associated with inflammatory back pain (IBP) in early spondyloarthropathy (SpA) remains unclear.


OBJECTIVE
To use MRI to study the sacroiliac joint (SIJ) and lumbar spine (LS) and explore the relationship between sites and extent of inflammation and HLA-B27 status over 12 months.


METHODS
54 patients with IBP; median duration 24 weeks (54% HLA-B27 positive; median Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) 5.65) and 22 control subjects (11 with mechanical back pain; 11 volunteers) were recruited and 63% (n = 34) were reassessed at 1 year. Fat saturation and T1-weighted MRI was performed with images being scored for active bone marrow oedema (BMO) lesions representative of inflammation.


RESULTS
At baseline 46/54 (85%) patients had BMO (SIJs and LS) compared with 40% in the control group. The majority of affected patients had inflammation at the SIJ level (96% (n = 44); 23.5% (n = 12) LS) and 28.3% (n = 13) at both sites simultaneously. The SIJ activity score confirmed more severe inflammation (BMO grade 2 or 3: 52.2%) in the IBP group (controls = BMO grade 1: 100%; p<0.001). HLA-B27 was associated with both the severity (p = 0.009) and number of baseline SIJ lesions (p = 0.045) and with persistence (SIJ or LS) at 1 year (p = 0.02). 90% of reattenders fulfilled European Spondyloarthropathy Study Group criteria; 73.5% showed MRI inflammation despite clinical improvement (median BASDAI 5.65 to 3.05; p<0.009).


CONCLUSIONS
LS and SIJ involvement may occur simultaneously in very early SpA and may be differentiated from non-inflammatory back pain by the severity of MRI lesions. HLA-B27 is associated with both the severity of osteitis and its persistence.
Marzo-Ortega
H
H
Section of Musculoskeletal Disease, Leeds Institute of Molecular Medicine, Chapel Allerton Hospital, Leeds LS7 4SA, UK. medhmo@leeds.ac.uk
McGonagle
D
D
O'Connor
P
P
Hensor
E M A
EM
Bennett
A N
AN
Green
M J
MJ
Emery
P
P
D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000097:blood; D001855:Bone Marrow Diseases / Q000209:etiology; D002097:C-Reactive Protein / Q000378:metabolism; D004487:Edema / Q000209:etiology; D005260:Female; D005500:Follow-Up Studies; D015796:HLA-B27 Antigen / Q000032:analysis*; D006801:Humans; D008159:Lumbar Vertebrae / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D012446:Sacroiliac Joint / Q000473:pathology*; D012720:Severity of Illness Index; D025242:Spondylarthropathies / Q000150:complications / Q000235:genetics / Q000473:pathology*; D055815:Young Adult
D015415:Biomarkers; D015796:HLA-B27 Antigen; D002097:C-Reactive Protein