Anterior Bony Bridges of the Sacroiliac Joints Are Associated with Male Sex but Not with the Development of DISH

Background

Diffuse Idiopathic Skeletal Hyperostosis (DISH) is characterized by ossification at entheses, predominantly affecting the axial skeleton and pelvis. Current diagnostic criteria require flowing osteophytes across at least four contiguous thoracic vertebrae, representing advanced end-stage condition. As anterior sacroiliac joint (SIJ) bone bridging is characteristic of DISH, we evaluated its potential role as an early predictor of DISH development.

Methods

This retrospective study included patients aged ≥ 40 years who underwent at least two chest and abdominal CT or PET-CT scans, with a minimum interval of seven years between examinations. Thoracic spine findings were classified as DISH, early DISH, or non-DISH using established criteria, and anterior SIJ bony bridging were assessed for presence and grade (low/high). Statistical comparisons were performed with Mann–Whitney, Pearson chi-square, or Fisher’s exact tests with multivariable regression analysis adjusted for age, sex and scans interval.

Results

Among patients with high-grade SIJ bridging at baseline, 26.5% developed full DISH during follow-up, compared with 11.7% of those with low-grade SIJ bridging (p=0.029). Univariable analysis showed baseline high-grade SIJ bridging increased odds for developing full DISH (OR, 2.7; 95% CI, 1.17–6.26). However, in multivariable models, baseline high-grade SIJ bridging lost its independent association with development of full DISH (p=0.33). Male sex (OR, 3.95; 95% CI, 1.94–8.06; p<0.0001) and older age at follow-up (OR, 1.04; 95% CI, 1.004–1.08; p=0.031) emerged as independent predictors of full DISH development.

Conclusion

The apparent association between SIJ bridging and DISH development is likely driven by male sex and advanced age, rather than representing an independent biological association.