Prevalence of vertebral deformity and its associations with physical impairment among Japanese women: The Hizen-Oshima study

Vertebral fractures are a hallmark of postmenopausal osteoporosis and an important end point in trials of osteoporosis treatment, but the clinical significance of vertebral deformities remains uncertain. We examined the prevalence of vertebral deformity and associations of vertebral deformities and other characteristics with physical functioning among 584 Japanese women ages 40 to 89 years. Lateral spine radiographs were obtained and radiographic vertebral deformities were assessed by quantitative morphometry, defined as vertebral heights more than 3 SD below the normal mean. A self-administered questionnaire was used to survey participants about difficulty in performing selected basic and instrumental activities of daily living (ADL). Overall, 15% of women had at least one vertebral deformity, and 8% had 2 or more. The prevalence of vertebral deformities increased progressively with age. Half of women ages 80 and over had vertebral deformities. Impaired function was defined as difficulty performing 3 or more ADLs. After adjusting for age, the odds of impaired function were increased by 1.4 times (95% CI: 0.7, 2.9) in women with a single vertebral deformity, and 3.1 times (1.4, 6.8) in those with two or more deformities. Additional adjustment for number of painful joints, number of comorbidities, body mass index, and back pain did not materially alter these findings. In conclusion, women with multiple vertebral deformities had significantly greater impaired function. The association was independent of age, back pain and the number of painful joints, suggesting that deformities may impair function even when back pain is not present.