Correlates of kyphosis in older women. The Fracture Intervention Trial Research Group.

OBJECTIVE

To determine the association between kyphosis (degree of forward curvature of the thoracic spine) and measures of spinal osteoporosis (height loss and vertebral fractures) and chronic back pain and disability in older women.

DESIGN

A cross-sectional study.

SETTING

Eleven clinical centers in the United States.

PARTICIPANTS

A total of 6439 community-dwelling osteoporotic women aged 55-80 enrolled in the Fracture Intervention Trial (FIT), a multicenter clinical trial of alendronate.

MEASUREMENTS

Thoracic curvature was measured at baseline using a Debreuner Kyphometer. Height loss was determined by subtracting current height measured with a Harpenden stadiometer from self-reported height at age 25. Vertebral fractures were defined by morphometry and semiquantitative reading of lateral thoracic and lumbar spine radiographs, and chronic back pain and back-related disability were assessed by questionnaire.

RESULTS

After adjustment for age, a 15 degrees increase in kyphosis was associated with losing more than 4 cm of height (OR, 1.88; 95% CI, 1.79-2.03) and having a vertebral fracture (OR, 1.57; 95% CI, 1.46-1.69). Kyphosis was more strongly related to thoracic fractures than to lumbar fractures, and kyphosis was most prominent in women with multiple thoracic wedge fractures. Kyphosis was also associated with upper back pain (OR per 15 degrees increase, 1.62; 95% CI 1.47-1.79) and middle back pain (OR per 15 degrees increase, 1.24; 95% CI 1.12-1.36), but it was not related to lower back pain (OR per 15 degrees increase, 0.98; 95% CI 0.90-1.05). Women with greater degrees of kyphosis were only slightly more likely to report back-related disability (OR per 15 degrees increase, 1.18; 95% CI 1.03-1.35) and poorer health status (OR per 15 degrees increase, 1.19; 95% CI 1.03-1.37).

CONCLUSIONS

Older women with greater degrees of kyphosis are likely to have other manifestations of spinal osteoporosis such as height loss and thoracic fractures and to suffer chronic upper and middle back pain. Measurement of kyphosis may be useful in assessing the severity of spinal osteoporosis.