Supplementary Material for: Relationship between the ratio of red cell distribution width to albumin and 28-day mortality among Chinese patients over 80 years with atrial fibrillation

Introduction: Atrial fibrillation (AF) is a prevalent heart arrhythmia in elderly adults aged 80 years or older. The red cell distribution width to albumin ratio has been acknowledged as a reliable prognostic marker for poor outcomes in a variety of disorders. However, there exists limited scientific evidence on the association of red cell distribution width to albumin (RAR) with mortality in geriatric individuals with AF. Methods: From January 2015 to June 2020, a retrospective study was conducted in a tertiary academic institution that diagnosed 1141 elderly adults with atrial fibrillation (AF). The RAR value was calculated as the ratio of RDW (%) to albumin (g/dL). The potential association between RAR and cardiovascular mortality and the risk of all-cause mortality within 28 days was evaluated by means of multivariable Cox regression analysis. Results: The 28-day all-cause and cardiovascular mortality rates were 8.7% and 3.3%, respectively. Increased RAR tertiles were found to be significantly associated with greater all-cause mortality (T1: 1.6%; T2: 6.2%; T3: 18.1%, P < 0.001) and cardiovascular mortality (T1: 0.8%; T2: 2.9%; T3: 6.3%, P < 0.001) using Kaplan‒Meier analysis. Continuous RAR had a positive association with all-cause mortality (HR=1.42, 95% CI 1.23-1.65) and cardiovascular mortality (HR=1.31, 95% CI 1.05-1.64), even after accounting for numerous confounding variables. In comparison to the T1 group, individuals with the highest RAR levels displayed a greater risk of all-cause mortality (HR=2.73, 95% CI 1.11-6.74) and cardiovascular mortality (HR=2.59, 95% CI 0.69-9.78). Increased RAR levels were related to higher rates of cardiovascular and all-cause mortality across almost all subgroups. Conclusion: RAR is independently correlated with 28-day all-cause mortality and cardiovascular mortality in AF-affected individuals aged ≥ 80. Keywords: cardiovascular disease; mortality; older; red cell distribution width; atrial fibrillation

引言：心房颤动（atrial fibrillation, AF）是80岁及以上老年人群中常见的心脏心律失常。红细胞分布宽度与白蛋白比值（red cell distribution width to albumin ratio, RAR）已被公认为多种疾病不良预后的可靠预后标志物。然而，目前关于RAR与心房颤动老年患者死亡率关联的科学证据较为有限。
方法：本研究于2015年1月至2020年6月在一家三级教学医院开展回顾性研究，共纳入1141例确诊心房颤动的老年患者。RAR值计算为红细胞分布宽度（red cell distribution width, RDW，%）与白蛋白（g/dL）的比值。通过多变量Cox回归分析，评估RAR与28天内心血管死亡率及全因死亡率风险的潜在关联。
结果：28天全因死亡率及心血管死亡率分别为8.7%和3.3%。卡普兰-梅尔分析（Kaplan-Meier）结果显示，RAR三分位水平升高与更高的全因死亡率（T1：1.6%；T2：6.2%；T3：18.1%，P<0.001）及心血管死亡率（T1：0.8%；T2：2.9%；T3：6.3%，P<0.001）显著相关。连续型RAR与全因死亡率（风险比（hazard ratio, HR）=1.42，95%置信区间（confidence interval, CI）：1.23~1.65）及心血管死亡率（HR=1.31，95%CI：1.05~1.64）呈正相关，即便在校正众多混杂变量后仍具有统计学意义。与T1组相比，RAR水平最高组患者的全因死亡（HR=2.73，95%CI：1.11~6.74）及心血管死亡（HR=2.59，95%CI：0.69~9.78）风险显著升高。几乎所有亚组中，RAR水平升高均与更高的心血管及全因死亡率相关。
结论：RAR与80岁及以上心房颤动患者的28天全因死亡率及心血管死亡率独立相关。
关键词：心血管疾病；死亡率；老年人；红细胞分布宽度；心房颤动