Impact of age on active and structural MRI lesions in sacroiliac joints of healthy individuals and non-specific back pain patients.

Abstract

Objective: To assess the impact of increasing age on the frequency of inflammatory and structural MRI lesions in the sacroiliac joints (SIJ) in 3 independent cohorts of healthy individuals and non-specific back pain (NSBP) patients.

Methods: We assessed MRI SIJ lesions in 3 cohorts A/B/C of healthy individuals (cohorts A/B: n=79/78) and NSBP patients (cohorts A/C: n=87/46) aged ≤45 years referred with back pain suspicious of axial spondyloarthritis (axSpA). MRI lesions were recorded on consecutive slices in SIJ quadrants or halves through the cartilaginous SIJ. Lesions were ascertained by 2-7 central readers according to standardized lesion definitions. Lesions recorded concordantly by majority of readers were analyzed according to age categories (20-29/30-39/40-45 years) and recently reported data-driven MRI cut-offs indicative of inflammatory or structural lesions typical of axSpA.

Results: Only 3.8%/3.8% of healthy individuals and 5.7%/4.3% of NSBP patients had erosion in ≥1 SIJ quadrant, and progressive increases of erosion with age categories were not evident. No healthy individual and 2.3%/4.3% of NSBP patients showed erosion in ≥3 SIJ quadrants, the cut-off indicative of axSpA; not a single individual met this cut-off in the highest age category. Fat metaplasia slightly increased with age among healthy individuals/NSBP in cohort A, not in cohorts B/C.

Conclusion: SIJ MRI data from healthy individuals and NSBP controls did not indicate progressive increases in structural lesions with increasing age categories when standardized definitions for axSpA lesions were adopted. MRI cut-offs for structural lesions denoting axSpA discriminated equally well between axSpA and NSBP across all age categories.