Prevalence of diffuse idiopathic skeletal hyperostosis (DISH) of the whole spine and its association with lumbar spondylosis and knee osteoarthritis: the ROAD study.

We aimed to assess the prevalence of diffuse idiopathic skeletal hyperostosis (DISH) and its association with lumbar spondylosis (LS) and knee osteoarthritis (KOA) using a population-based cohort study entitled Research on Osteoarthritis/osteoporosis Against Disability (ROAD). In the baseline ROAD study, which was performed between 2005 and 2007, 1,690 participants in mountainous and coastal areas underwent anthropometric measurements and radiographic examinations of the whole spine (cervical, thoracic, and lumbar) and both knees. They also completed an interviewer-administered questionnaire. Presence of DISH was diagnosed according to Resnick criteria, and LS and KOA were defined as Kellgren-Lawrence (KL) grade ≥3. Among the 1,690 participants, whole-spine radiographs of 1,647 individuals (97.5%; 573 men, 1,074 women; mean age, 65.3 years) were evaluated. Prevalence of DISH was 10.8% (men 22.0%, women 4.8%), and was significantly higher in older participants (presence of DISH 72.3 years, absence of DISH 64.4 years) and mainly distributed at the thoracic spine (88.7%). Logistic regression analysis revealed that presence of DISH was significantly associated with older age [+1 year, odds ratio (OR): 1.06, 95% confidence interval (CI): 1.03-1.14], male sex (OR: 5.55, 95% CI: 3.57-8.63), higher body mass index (+1 kg/m(2), OR: 1.08, 95% CI: 1.02-1.14), presence of LS (KL2 vs KL0: 1, OR: 5.50, 95% CI: 2.81-10.8) (KL ≥3 vs KL0: 1, OR: 4.09, 95% CI: 2.08-8.03), and presence of KOA (KL ≥3 vs KL0: 1, OR: 1.89, 95% CI: 1.14-3.10) after adjusting for smoking, alcohol consumption, and residential area (mountainous vs coastal). This cross-sectional population-based study clarified the prevalence of DISH in general inhabitants and its significant association with LS and severe KOA.