Supplementary Material for: Blood-based frailty index in patients with acute ischemic stroke undergoing endovascular treatment

Introduction: Frailty is a syndrome depicting vulnerability of multiple physiological systems to stressors. Frailty measures, such as Hospital Frailty Risk Score (HFRS), can be used to identify frailty and predict outcome more reliably. Our aim was to analyse a blood-based frailty index (FI-B) at admission for prediction outcome of patients with acute ischemic stroke (AIS) undergoing endovascular treatment (EVT).
Methods: We conducted a retrospective study of consecutive AIS patients undergoing EVT in a single tertiary centre during a period of five years. A set of eighteen blood parameters at admission were collected and nine of these were utilized to calculate FI-B. We analysed the relationship between FI-B and HFRS. We examined the baseline characteristics of the study population based on FI-B-tertiles. Multivariable regression models were employed to ascertain the association between FI-B and in-hospital mortality, 3-month mortality and 3-month functional outcome.
Results: The final study population comprised 489 patients, with a median age of 75.6 years, 49.5% of patients were male. The FI-B exhibited a weak positive correlation with HFRS (rho=0.113, p=0.016). Patients in higher FI-B-tertiles were older and more frequently presented with pre-stroke functional dependence and comorbidities. Moreover, an increasing FI-B was independently associated with increased likelihood of in-hospital mortality (adjusted odds ratio [aOR]=1.29, 95% confidence interval [95%CI]=1.14-1.47), 3-month mortality (aOR=1.26, 95%CI=1.11-1.43), and of increasing 3-month functional disability measured by utility-weighted modified Rankin Scale (common aOR=0.84, 95%CI=0.76-0.93).
Conclusion: A frailty index based on blood values at admission was able to identify frailty in AIS patients undergoing EVT and was an independent predictor of short- and medium-term outcome after stroke.

引言：衰弱综合征是指多生理系统对应激源的易感性升高。诸如住院衰弱风险评分（Hospital Frailty Risk Score, HFRS）这类衰弱评估工具，可用于更可靠地识别衰弱状态并预测临床结局。本研究旨在分析入院时采集的血液源性衰弱指数（blood-based frailty index, FI-B）对接受血管内治疗（endovascular treatment, EVT）的急性缺血性脑卒中（acute ischemic stroke, AIS）患者的临床结局预测价值。
方法：本研究为回顾性研究，纳入某单中心三级医疗中心5年内连续收治的接受血管内治疗的急性缺血性脑卒中患者。收集患者入院时的18项血液学参数，选取其中9项计算FI-B。分析FI-B与HFRS的相关性；依据FI-B三分位数对研究队列进行分组，探讨不同分组的基线特征；采用多变量回归模型明确FI-B与住院死亡率、3个月死亡率及3个月功能预后的关联。
结果：最终纳入分析的研究队列共489例患者，中位年龄为75.6岁，男性占比49.5%。FI-B与HFRS呈弱正相关（rho=0.113，P=0.016）。FI-B较高三分位数组的患者年龄更大，卒中前功能依赖及合并症发生率更高。此外，FI-B升高与住院死亡率（校正比值比[aOR]=1.29，95%置信区间[95%CI]=1.14~1.47）、3个月死亡率（aOR=1.26，95%CI=1.11~1.43）升高独立相关，同时与采用效用加权改良Rankin量表评估的3个月功能残疾程度加重独立相关（共同校正比值比=0.84，95%CI=0.76~0.93）。
结论：基于入院时血液学指标构建的衰弱指数，可有效识别接受血管内治疗的急性缺血性脑卒中患者的衰弱状态，同时可作为卒中后短期及中期临床结局的独立预测因子。