Objective: Assessment of spinal lateral flexion (SLF) is important in spondyloarthritis (SpA). The INSPIRE method of measuring SLF requires one set of measurements, is faster, feasible, and correlates with the mSASSS in ankylosing spondylitis. The present study aimed to compare the INSPIRE to Domjan method in PsA patients and correlate with radiographic changes.
Methods: Patients were selected from a cohort followed in a PsA clinic. Patients satisfying CASPAR criteria and having axial disease were identified. Clinical features were recorded. Examination included full spinal clinimetrics including measurement of INSPIRE and Domjan methods. Spine radiographs were scored for mSASSS by two assessors. Pearson correlation was used to correlate the values of spinal mobility measures and radiographic scores.
Results: Two hundred twenty-nine patients were included in the study. The mean age at study entry was 51 years (16-83) and mean disease duration was 14 years (0.1-49). Forty and 47% of patients had radiographic evidence of unilateral or bilateral sacroiliitis. The mean modified Schober was 4.5 (1-8 cm), SLF-Domjan 16.5 (3.5-40 cm), SLF-INSPIRE 31.5 (8-60 cm), and mSASSS score 4(0-48). Correlation (95% CI) between INSPIRE and Domjan method was 0.87 (0.82, 0.90), between INSPIRE, Domjan method, and mSASSS were - 0.36 (- 0.50, - 0.20) and - 0.34 (- 0.49, - 0.18) respectively. All correlations were significant. Comparable correlations were obtained with comparisons made in patients of PsA with axial disease only.
Conclusion: Both INSPIRE and Domjan methods correlate well as measures of SLF in PsA and correlate with radiographic damage. Therefore, the simpler INSPIRE method may be used to measure SLF in PsA.
Keywords: Axial disease; Domjan; INSPIRE; Lumbar lateral flexion; Psoriatic arthritis.