Prevalence and related factors of early-phase diffuse idiopathic skeletal hyperostosis in a community-dwelling population - A cross-sectional observational study.

Background: The concept of early-phase diffuse idiopathic skeletal hyperostosis (EDISH) was recently introduced and its prevalence at the thoracic spine level was revealed. Some cases of EDISH progress to diffuse idiopathic skeletal hyperostosis (DISH) in association with being overweight. The prevalence and distribution of EDISH in the whole spine and related factors are unclear. The purpose of this study is to identify the prevalence and ossification patterns of EDISH, termed EDISH, as well as factors associated with the severity of ossification in a community-dwelling Japanese population.

Methods: A cohort study based on an observational health check-up project. The study included 524 participants (215 men and 309 women) from a community health checkup in 2021. Each participant underwent lateral whole spine radiography for evaluation of intervertebral ossification and was allocated into one of three groups accordingly: no DISH (NDISH), EDISH, and DISH. We recorded the body composition and laboratory data. Factors associated with ossification were investigated using multivariable regression analysis.

Results: The prevalence of EDISH was 5.5 % overall (10.2 % in men and 2.3 % in women). The prevalence of DISH was 7.4 %, and the prevalence was significantly higher in men (P < .001). The center and lower end of ossification were most observed at the lower thoracic level. Age was significantly higher in the EDISH and DISH groups than in the NDISH group. Multivariable analysis revealed that the severity of ossification was associated with the percentage of body fat, insulin-like growth factor-1, adiponectin, and high-density lipoprotein-cholesterol.

Conclusion: The overall prevalence of EDISH and DISH was 5.5 % and 7.4 %, respectively, and the prevalence of both conditions was higher in men. Our analysis suggests that the center of ossification was the lower thoracic level, with gradual development. Lipid metabolism may be associated with ossification.