The association of kyphosis assessed in supine and standing positions with future activities of daily living dependence: the Kurabuchi Study

Summary: We investigated the longitudinal association of noninvasively evaluated kyphotic posture with future dependence in activities of daily living and death in a community-dwelling older Japanese. We found that the association with outcomes varied according to the types of kyphotic posture. Introduction: We have previously found an association between severe kyphosis and future dependence in activities of daily living (ADL) in people who manifest the condition in the supine position (structural curvature). However, because some people show severe kyphosis only in the standing position (postural curvature), we combined our noninvasively obtained kyphosis measurements from participants in the supine position (block method) with those obtained from participants in the standing position (kyphosis index) to determine whether not only structural curvature but also postural curvature is associated with ADL dependence and death. Methods: Between 2005 and 2006, we carried out health evaluations of adults aged 65 years or older in Kurabuchi Town, Japan: 792 participants (337 males, 455 females) who were independent in ADL at baseline and underwent evaluation of kyphotic posture were followed up until March 2014 (mean follow-up: 7.5 years). Participants who experienced one or more admissions to a nursing home, certification of a need for long-term care/support, or a decline in the Katz ADL Index during the follow-up period were defined as being dependent in ADL. Results: A flat back (straight spine in a standing position) and structural curvature were associated with future ADL dependence, but postural curvature was not. The multivariate-adjusted odds ratios (95% confidence interval) compared with physiological curvature (physiological curvature in a standing position) as the reference were 1.72 (1.04–2.86) for a flat back and 2.76 (1.59–4.79) for structural curvature. A weak association with death was observed in those with structural curvature. Conclusions: Our results suggest that the prognoses of people with kyphosis differ according to the type of kyphotic posture.