Kyphosis and decline in physical function over 15 years in older community-dwelling women: the Study of Osteoporotic Fractures.

BACKGROUND Maintaining physical function is an important prerequisite for preserving independence in later life. Greater degrees of kyphosis in the thoracic spine are prevalent in older persons and accompanied by reduced physical function in multiple cross-sectional studies. It is unknown whether kyphosis predicts worse physical function over time. METHODS We retrospectively assessed whether greater magnitude of kyphosis is associated with decline in self-reported and objectively measured physical function over 15 years. Digitized Cobb angle kyphosis (T4-T12) was derived from supine lateral thoracic spine radiographs in a cohort of 1,196 women aged 65 and older (mean = 69.3 years [SD = 4.0]). Using regression models, we evaluated associations of baseline kyphosis with both self-reported functional status and objectively measured gait speed, grip strength, and timed chair stands cross-sectionally and as change assessed over 15 years. RESULTS In cross-sectional multivariate analyses, with each 10-degree increment of kyphosis, grip strength was 0.24 kg lower (p = .02), but there were no significant associations between kyphosis and functional status, gait speed, or timed chair stand, likely reflecting the high functioning study participants. In multivariate longitudinal analysis, with each 10-degree increment in baseline kyphosis, there was 0.07 point additional decline in functional status (p = .09), 0.01 m/s more decline in gait speed (p = .07), and 0.32 s greater decline in time to complete five chair stands (p = .004), but no association with decline in grip strength. CONCLUSIONS Greater magnitude of kyphosis may predict worsening lower extremity function over time in older women. Early recognition and preventative measures against kyphosis progression may help preserve physical function over the long term.