Differences in prevalence and associated factors between mild and severe vertebral fractures in Japanese men and women: the third survey of the ROAD study

Vertebral fracture (VF) is a common osteoporotic fracture, while its epidemiology varies according to regions and ethnicities, little is known about it in Japan. Using whole-spine radiographs from a population-based cohort study, the Research on Osteoarthritis/Osteoporosis Against Disability study 3rd survey performed in 2012–2013, we estimated the sex- and age-specific prevalence of VF in the Japanese. Genant’s semiquantitative method (SQ) was used to define VF; SQ ≥ 1 as VF, SQ = 1 as mild VF, SQ≥ 2 as severe VF. We also revealed accurate site-specific prevalence, and associated factors with mild and severe VF. The participants were 506 men [mean age 66.3 years, standard deviation (SD):13.0] and 1038 women (mean age 65.3 years, SD: 12.6). The prevalence of VF in participants aged under 40, in their 40s, 50s, 60s, 70s, and ≥ 80 years was 17.4, 7.9, 18.5, 25.6, 26.3, and 41.5%, respectively, in men, and 2.9%, 2.4%, 7,3, 10.3, 27.1, and 53.0%, respectively, in women. Men had a significantly higher prevalence of mild VF (21.2%) than women (10.0%, p < 0.001); whereas, severe VF was significantly more prevalent in women (9.1%) than in men (4.7%, p = 0.003). VF was distributed with 2 peaks regarding site; one large peak at the thoracolumbar region, and another at the middle thoracic lesion. Low back pain and decreased walking ability were independently associated with severe VF, but not with mild VF, after adjustment for participant characteristics. Decreased walking ability was associated with multiple VFs in women, but not in men.