Supplementary Material for: Mortality rates and a clinical predictive model for the elderly on maintenance hemodialysis: A large observational cohort study of 17,354 Asian patients

Background: Mortality following hemodialysis initiation may influence the decision to initiate hemodialysis in elderly patients. Our objective is to demonstrate mortality following hemodialysis initiation in elderly (≥70 years) and to derive a prediction risk score based on clinical and laboratory indicators to determine risk of all-cause mortality in patients aged ≥80 years.
Methods: We identified elderly (≥70 years) who initiated maintenance hemodialysis between January 2005 and December 2016 using data from the Thai Renal Replacement Therapy Registry. The mortality rate was determined based on age categories. A predictive risk score for all-cause mortality was created for 4,451 patients aged ≥80 years by using demographics, laboratory values, and interview-based parameters. Using a flexible parametric survival analysis, we predicted mortality 3, 6 months, 1, 5, and 10 years after hemodialysis initiation.
Results: 17,354 patients (≥70 years) were included, mean age 76.9±5.1 years, 46.5% male, and 6,309 (36.4%) died. Patient aged <80 years had a median survival time of 110.6 months. A 9-point risk score was developed to predict mortality in patients aged ≥80 years: age>85 years, male, body mass index<18.5 kg/m2, hemoglobin<10.0 g/dL, albumin<3.5 g/dL, substantial assistance required in daily living (1 point each), and Karnofsky Performance Score<50 (3 points). C-statistic of 0.797 indicated high model discrimination. Internal validation demonstrated good agreement between observed and anticipated mortality.
Conclusions: Hemodialysis is appropriate for patients aged 70–80 years. A risk score for mortality in patients aged ≥80 years has been developed. The score is based on seven readily obtainable and evaluable clinical characteristics.

背景：老年患者启动血液透析后的死亡率，可能会影响临床医师对其启动血液透析的决策。本研究旨在明确≥70岁老年患者启动血液透析后的死亡率情况，并基于临床与实验室指标推导预测风险评分，以评估≥80岁老年患者的全因死亡风险。

方法：本研究依托泰国肾脏替代治疗登记库（Thai Renal Replacement Therapy Registry）的数据，纳入2005年1月至2016年12月期间启动维持性血液透析的≥70岁老年患者。按年龄分组计算患者的死亡率；针对4451例≥80岁的患者，结合人口学特征、实验室检测指标及访谈获取的参数，构建全因死亡预测风险评分模型。采用灵活参数生存分析，预测患者启动血液透析后3个月、6个月、1年、5年及10年的死亡风险。

结果：本研究共纳入17354例≥70岁的患者，平均年龄为76.9±5.1岁，其中男性占比46.5%，6309例（36.4%）患者死亡。年龄＜80岁的患者中位生存时间为110.6个月。针对≥80岁的患者，本研究构建了9分制死亡预测风险评分：年龄＞85岁、男性、体质量指数（body mass index, BMI）＜18.5 kg/m²、血红蛋白（hemoglobin）＜10.0 g/dL、白蛋白（albumin）＜3.5 g/dL、日常生活需大量协助，以上各项各计1分；卡氏功能状态评分（Karnofsky Performance Score）＜50分计3分。该模型的C统计量（C-statistic）为0.797，提示具备良好的模型区分度；内部验证结果显示，模型预测的死亡情况与实际观测结果吻合度佳。

结论：血液透析适用于70~80岁的老年患者。本研究已构建针对≥80岁老年患者的死亡风险评分，该评分基于7项易于获取且可评估的临床特征。