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.