Association of kyphotic posture with loss of independence and mortality in a community-based prospective cohort study: the Locomotive Syndrome and Health Outcomes in Aizu Cohort Study (LOHAS)

Abstract

Objectives This study aimed to investigate the association between kyphotic posture and future loss of independence (LOI) and mortality in community-dwelling older adults. Design Prospective cohort study. Setting Two Japanese municipalities. Participants We enrolled 2193 independent community-dwelling older adults aged≥65 years at the time of their baseline health check-up in 2008. Kyphotic posture was evaluated using the wall-occiput test (WOT) and classified into three categories: non-kyphotic, mild (>0 and ≤4 cm) and severe (>4 cm). Primary and secondary outcome measures The primary outcome was mortality and the secondary outcomes were LOI (new long-term care insurance certification levels 1-5) and a composite of LOI and mortality. A Cox proportional hazards model was used to estimate the adjusted HRs (aHRs). Results Of the 2193 subjects enrolled, 1621 were included in the primary analysis. Among these, 272 (17%) and 202 (12%) were diagnosed with mild and severe kyphotic postures, respectively. The median follow-up time was 5.8 years. Compared with the non-kyphotic group, the aHRs for mortality were 1.17 (95% CI 0.70 to 1.96) and 1.99 (95% CI 1.20 to 3.30) in the mild and severe kyphotic posture groups, respectively. In the secondary analysis, a consistent association was observed for LOI (mild: aHR 1.70, 95% CI 1.13 to 2.55; severe: aHR 2.08, 95% CI 1.39 to 3.10) and the LOI-mortality composite (mild: aHR 1.27, 95% CI 0.90 to 1.79; severe: aHR 1.83, 95% CI 1.31 to 2.56). Conclusion Kyphotic posture was associated with LOI and mortality in community-dwelling older adults. Identifying the population with kyphotic posture using the WOT might help improve community health.