Supplementary Material for: A Study of Clinical Features and Risk Factors of Self-Referring Emergency Department Headache Patients: A Comparison with Headache Center Outpatients

Background: Nonlife-threatening headaches account for 3% of emergency department (ED) admissions, with social and economic negative consequences. We aim to investigate clinical features and risk factors of nonlife-threatening headache patients referring to ED versus those referring to headache outpatient clinics. Methods: During 6 months, we promptly reevaluated in our headache unit (HU) patients discharged from ED. We compared the clinical characteristics of patients who referred to ED with those of HU outpatients visited in the same time interval. Discriminant Function Analysis and Correspondence Analysis were used to determine risk factors for ED referral. Results: We recruited 49 post-ED patients and 126 outpatients. The main reasons for ED admission were poor response to acute treatment and aura-related symptoms. Headache diagnoses made in ED were generally not confirmed later (overall concordance of 47%), except for cluster headache (CH) and migraine with aura (MA). ED patients complained higher headache intensity, longer duration, and prolonged aura compared to outpatients. Aura was the main risk factor associated with ED admission on statistical models, while less prominent risk factors were sex, age, and years from migraine onset. Conclusions: ED patients presented a more severe headache clinical phenotype compared with outpatients. Headache diagnosis remains difficult in the emergency setting and is more easily achieved for the headache forms with standout features, such as MA or CH. According to statistical models, the aura is the most important risk factor for ED admissions.背景：非致命性头痛占急诊科（Emergency Department, ED）就诊人次的3%，并可引发不良社会与经济后果。本研究旨在对比就诊于急诊科与头痛门诊的非致命性头痛患者的临床特征及危险因素。 方法：在6个月的研究周期内，我们对从急诊科转诊至本院头痛诊疗单元（Headache Unit, HU）的出院患者进行了及时复诊。我们对比了同期就诊于急诊科的患者与头痛门诊患者的临床特征。本研究采用判别函数分析与对应分析，以明确急诊科就诊的危险因素。 结果：本研究共纳入49名急诊科转诊患者与126名门诊患者。急诊科患者就诊的主要原因为急性治疗应答不佳及先兆相关症状。急诊科作出的头痛诊断后续大多未得到证实，总体诊断一致性仅为47%，仅丛集性头痛（Cluster Headache, CH）与有先兆偏头痛（Migraine with Aura, MA）除外。与门诊患者相比，急诊科就诊患者的头痛程度更重、发作持续时间更长，且先兆持续时间更久。统计模型显示，先兆是与急诊科就诊相关的最主要危险因素，而性别、年龄及偏头痛起病年限则为相对次要的危险因素。 结论：与门诊头痛患者相比，急诊科就诊患者的头痛临床表型更为严重。急诊环境下的头痛诊断仍存在较大难度，仅具备显著特征的头痛类型（如有先兆偏头痛或丛集性头痛）更易得到准确诊断。根据统计模型结果，先兆是急诊科就诊的最关键危险因素。