Background Ankylosing spondylitis is associated with reduced spinal mobility. Little is known about the spinal mobility in early axial spondyloarthritis (axSpA) and how it compares to patients with other forms of chronic back pain (CBP).
Objectives The aim was to compare spinal mobility in patients with CBP of short duration with reference mobility curves from the general population and to examine whether frequently used spinal mobility measures (SMM) can discriminate between axSpA and other forms of CBP.
Methods The SPACE-cohort includes patients with CBP (≥3 months, ≤2 years, onset <45 years) recruited from 5 centres in Europe. The CBP patients were classified as axSpA (fulfilling the ASAS criteria), possible axSpA (possSpA) (not fulfilling ASAS criteria but ≥1 axSpA feature) or not having SpA (noSpA).
Spinal mobility was assessed with lateral spinal flexion (LSF), chest expansion (CE), intermalleolar distance (IMD), modified Schober (MS), cervical rotation (CR) and occiput-to-wall distance (OWD).
SMM, except OWD, were defined as impaired if below the 5th percentile reference curve from general population, given their age and for CE and IMD also height, following the equations of mobility curves for each measures1. OWD >0 was considered impaired. The proportion of patients with impaired spinal mobility for each measure was compared across the patient groups using Chi square.
Results In total 393 CBP-patients were included: 142 axSpA, 139 possSpA and 112 noSpA. Some characteristics of patients with axSpA were statistically significant different compared to possSpA and noSpA: a larger proportion (%) was male 48/28/27, reported less back pain (NRS 0–10) median 4.0/6.0/6.0 and patients with axSpA were taller (cm) than patients with possSpA mean 177/173/174.
In all CBP patients, the most frequently impaired mobility measure was LSF 40% followed by CE 22%, CR 18%, IMD 17%, MS 15% and OWD 11% (table 1). No statistically significant differences in proportion of patients with impaired spinal mobility were found between the CBP subgroups.
Conclusions Among patients with CBP of short duration, between15–40% had a spinal mobility below the 5th percentile in the general population depending on the measurement used. The most affected SMM was LSF. Impaired spinal mobility was equally prevalent in patients with axSpA and other causes of CBP. Our findings suggest that the SMM recommended for axSpA may be of little differential diagnostic value.
Ramiro ARD 2015
Disclosure of Interest None declared