Impact of Diffuse Idiopathic Skeletal Hyperostosis on Sagittal Spinal Alignment in the General Elderly Population: A Japanese Cohort Survey Randomly Sampled from a Basic Resident Registry

Interest is mounting regarding diffuse idiopathic skeletal hyperostosis (DISH) as the rate in the elderly increases. Although some studies have demonstrated an effect of DISH on sagittal spinal alignment, the pathogenetic mechanism remains unknown. Random sampling from the basic resident registry of a rural town for subject selection was used to investigate the impact of DISH on sagittal spinal alignment. METHODS: Registered citizens who were 50 to 89 years of age were targeted for this survey. We divided the study population into 8 groups based on sex (male and female) and age (50 to 59, 60 to 69, 70 to 79, and 80 to 89 years) after random sampling from the resident registry of the town of Obuse in 2014. A total of 411 participants (202 male and 209 female) were enrolled and underwent a whole-spine lateral radiographic examination. We investigated the spinal level of DISH occurrence, measured sagittal spinal alignment parameters, and analyzed the effects of clinical factors on DISH using multivariate analysis. RESULTS: A total of 66 participants (16.1%) were identified as having DISH in our population cohort. With regard to DISH involving the thoracic spine, sagittal vertical axis, cervical sagittal vertical axis, T1 slope, thoracic kyphosis, aging, and male sex were significantly associated with DISH in the univariate analysis. Aging and male sex were also independent factors according to multivariate analysis; the odds ratio (OR) was 1.70 for aging per decade and 3.75 for male sex. Sagittal vertical axis, lumbar lordosis, sacral slope, pelvic tilt, aging, and male sex had significant associations with DISH involving the lumbar spine in univariate analysis, with decreased lumbar lordosis (OR, 1.82), aging per decade (OR, 4.35), and male sex (OR, 10.7) as independent factors in multivariate analysis. CONCLUSIONS: In this study examining the impact of DISH on sagittal spinal alignment in a general population, decreased lumbar lordosis was significantly associated with DISH involving the lumbar spine in the healthy community-dwelling elderly population, and no sagittal spine parameters were significantly related to DISH affecting the thoracic spine. CLINICAL RELEVANCE: When there is decreased lumbar lordosis in elderly people, we should check for the existence of DISH.