Supplementary Material for: Potassium Iodide for Cutaneous Inflammatory Disorders: A Monocentric, Retrospective Study

<b><i>Objectives:</i></b> Potassium iodide (KI) is a medication that has been used for decades in dermatology and it is mentioned as a treatment option in all major dermatology textbooks. Yet, there is little recent information on its efficacy. In our study, we wanted to retrospectively evaluate the therapy response to KI in our patients. <b><i>Methods:</i></b> The hospital information system was searched for patients treated with KI at the Department of Dermatology (University Hospital Zurich) in the last 20 years (January 1, 1998 to December 31, 2017). A total of 52 patients were found and, subsequently, 35 patients were included in our study. <b><i>Results:</i></b> KI was prescribed for the following skin conditions: erythema nodosum, disseminated granuloma anulare, necrobiosis lipoidica, nodular vasculitis, cutaneous sarcoidosis, and granulomatous perioral dermatitis/ rosacea. The median duration of KI intake was 5 ± 7.7 weeks (range 1–26). The global assessment of efficacy by the treating physician showed an improvement of disease in about a third of all patients. No response was seen in 14 patients and 9 even had a progression of disease. An adverse event was documented in 16 cases. <b><i>Conclusions:</i></b> Our findings show that an improvement was reached in only about a third of all cases. High response rates with only mild side effects (in 16 out of 35 patients) were observed.

**研究目的**：碘化钾（Potassium iodide, KI）是一种已应用于皮肤病学领域数十年的临床药物，所有主流皮肤病学教科书均将其列为治疗选择之一。然而近年来关于其疗效的公开资料却较为匮乏。本研究旨在回顾性评估本院患者接受KI治疗后的临床应答情况。

**研究方法**：检索苏黎世大学医院皮肤科1998年1月1日至2017年12月31日这20年间，接受KI治疗的患者的医院信息系统记录，共筛选出52例患者，最终纳入本研究的患者共35例。

**研究结果**：KI被用于治疗以下皮肤疾病：结节性红斑、播散性环状肉芽肿、脂质渐进性坏死、结节性血管炎、皮肤结节病以及肉芽肿性口周皮炎/酒渣鼻。患者服用KI的中位疗程为5±7.7周，疗程范围为1~26周。接诊医师对疗效的整体评估显示，约三分之一的患者病情得到改善；14例患者未出现临床应答，另有9例患者病情甚至出现进展。共有16例患者记录到不良事件。

**研究结论**：本研究结果显示，仅约三分之一的病例可通过KI治疗获得病情改善。尽管仅35例患者中有16例出现了轻度不良反应，但本研究仍观察到了较高的治疗应答率。