Kyphosis and Sleep Characteristics in Older Persons: The Rancho Bernardo Study

BACKGROUND Kyphosis is a forward curvature of the thoracic spine that is associated with multiple adverse health outcomes. This cross-sectional study examined the association between kyphosis and sleep characteristics. METHODS Participants were 468 white, community-dwelling individuals (women = 255; men = 213) from the Rancho Bernardo cohort who had kyphosis assessed using a flexicurve ruler at a 2007-09 follow-up research clinic visit and sleep quality assessed by mailed survey in 2010 with the Pittsburgh Sleep Quality Index (PSQI), scored 0-18, with >5 indicative of poor sleep quality. RESULTS Women had a mean age of 73.3 ± 8.8 years; men 74.2 ± 8.1 years. Mean flexicurve measures were 12.6 ± 3.2 for women and 12.1 ± 2.6 for men. No significant associations were found between kyphosis and any self-reported sleep measure in men, but women with worse kyphosis had poorer sleep quality, based on total PSQI score and two PSQI subcomponents. In women, with each unit increase in kyphosis, after adjusting for age, marital status, height, general health, calcium supplement use, estrogen use, exercise, arthritis, and depression, there was an associated increase in total PSQI score, indicating worse sleep quality (standard β-estimate = 1.37, 95% CI: 1.03, 1.82). Women with worse kyphosis were also more likely to sleep ≤ 7 hours (Odds Ratio (OR) = 1.11, 95% CI: 1.02, 1.22) and report use of sleep medications (OR = 1.14, 95% CI: 1.03, 1.25). CONCLUSIONS In women only, those with worse flexicurve kyphosis had worse scores on the PSQI, slept fewer hours (≤ 7 hours) and were more likely to report sleep medication use than those with less kyphosis. The association between kyphosis and objective sleep measures in older persons deserves further investigation.