Department of Medicine, University of Minnesota, Minneapolis, MN, USA.
Division of Epidemiology and Community Health, University of Minnesota, Minneapolis, MN, USA.
J Bone Miner Res. 2018 Sep;33(9):1595-1602. doi: 10.1002/jbmr.3462.
Previous studies examining the association of cognitive impairment and dementia with fracture outcomes in older adults have usually used standard approaches that did not take into account the competing risk of mortality. However, ignoring mortality may not provide accurate estimates of risk of fracture because dementia in older adults strongly predicts death, making mortality a competing risk. A total of 1491 women (mean age 87.6 years) participating in the prospective Study of Osteoporotic Fractures (SOF) Year 20 exam were cognitively assessed and followed to ascertain vital status (deaths verified by death certificates) and hip fractures (confirmed by radiographic reports). Cognitive status was categorized as normal, mild cognitive impairment (MCI), or dementia, based on a standardized evaluation. Absolute probability of hip fracture by category of cognitive function was estimated using traditional Kaplan-Meier method and cumulative incidence function accounting for competing mortality risk. Risk of hip fracture by cognitive function category was determined using conventional Cox proportional hazards regression and subdistribution hazards models with death as a competing risk. During an average follow-up of 5.6 years, 139 (9.3%) women experienced a hip fracture and 990 (66.4%) died before experiencing this outcome. Among women with dementia, the risk of hip fracture was 11.7% (95% confidence interval [CI] 7.3-17.2) at 5 years and 18.6% (95% CI 9.1-30.9) at 10 years using traditional survival analysis versus 7.9% (95% CI 5.1-11.6) at 5 years and 8.8% (95% CI 5.8-12.8) at 9.8 years using a competing risk approach. Results were similar for women with MCI. Women with MCI and dementia have a higher risk of hip fractures than women with normal cognition. However, not taking into account the competing risk of mortality significantly overestimates the risk of hip fracture in women in the ninth and tenth decades of life with cognitive impairment. © 2018 American Society for Bone and Mineral Research.
先前研究认知障碍和痴呆与老年人骨折结局的关联通常使用标准方法，这些方法没有考虑到死亡率的竞争风险。然而，忽略死亡率可能无法准确估计骨折风险，因为老年人痴呆强烈预示着死亡，使死亡率成为竞争风险。共有 1491 名女性（平均年龄 87.6 岁）参加了前瞻性骨质疏松性骨折研究（SOF）20 年检查，进行了认知评估，并随访以确定生命状态（通过死亡证明核实死亡）和髋部骨折（通过放射报告证实）。认知状态根据标准化评估分为正常、轻度认知障碍（MCI）或痴呆。使用传统的 Kaplan-Meier 方法和累积发生率函数（考虑到竞争死亡风险）按认知功能类别估计髋部骨折的绝对概率。使用传统的 Cox 比例风险回归和亚分布风险模型（以死亡为竞争风险）确定认知功能类别与髋部骨折风险的关系。在平均 5.6 年的随访期间，139 名（9.3%）女性经历了髋部骨折，990 名（66.4%）女性在经历这种结局之前死亡。在痴呆女性中，使用传统生存分析，髋部骨折风险在 5 年时为 11.7%（95%CI 7.3-17.2），在 10 年时为 18.6%（95%CI 9.1-30.9），而使用竞争风险方法，髋部骨折风险在 5 年时为 7.9%（95%CI 5.1-11.6），在 9.8 年时为 8.8%（95%CI 5.8-12.8）。MCI 女性的结果相似。有 MCI 和痴呆的女性发生髋部骨折的风险高于认知正常的女性。然而，不考虑死亡率的竞争风险会显著高估认知障碍女性在生命的第九和第十个十年中髋部骨折的风险。 © 2018 美国骨与矿物质研究协会。
