Background The neuropsychiatric side effects of efavirenz occur mainly early during treatment and are usually mild. A lesser-known and serious complication is late-onset efavirenz toxicity causing ataxia and encephalopathy. Data regarding this condition are limited. Objectives We describe the clinical picture of late-onset efavirenz toxicity, investigate co-morbidities and report outcomes. Method This descriptive study of all patients with late-onset efavirenz toxicity was conducted over three years at Kalafong Provincial Tertiary Hospital, Pretoria, South Africa. Results Forty consecutive patients were identified. Mean age was 42.1 years, three patients (7.5%) were male and the mean efavirenz level was 49.0 μg/mL (standard deviation [s.d.]: 24.8). Cerebellar ataxia (82.5%) and encephalopathy (47.5%) were the most common presenting features (40.0% had both); four patients presented with psychosis. Presence of encephalopathy and/or cerebellar ataxia was associated with higher efavirenz levels compared with psychosis (52.1 μg/mL, s.d.: 24.1 vs 25.0 μg/mL, s.d.: 17.1). In most patients, symptoms resolved, but four patients (10.0%) died, and one patient remained ataxic. Conclusion Late-onset efavirenz toxicity typically presented with ataxia and encephalopathy, but psychosis can be the presenting feature. The outcome after withdrawal was good, but the mortality of 10.0% is concerning. Recent changes in guidelines favour dolutegravir, but many patients remain on efavirenz, and awareness of the condition is vital. What this study adds This large, single-centre study contributes to the limited data of HIV-positive patients with late-onset efavirenz toxicity and emphasises its ongoing relevance in clinical practice.

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迟发性依非韦伦毒性：一项来自南非比勒陀利亚的描述性研究。

背景 依非韦伦的神经精神副作用主要发生在治疗早期，而且通常很轻微。一种鲜为人知的严重并发症是迟发性依非韦伦毒性导致共济失调和脑病。关于这种情况的数据是有限的。目标 我们描述迟发性依非韦伦毒性的临床表现，调查合并症并报告结果。方法 这项描述性研究在南非比勒陀利亚的 Kalafong 省三级医院进行了三年多，对所有迟发性依非韦伦毒性患者进行了描述性研究。结果 确定了 40 名连续患者。平均年龄为 42.1 岁，三名患者 (7.5%) 为男性，平均依非韦伦水平为 49.0 μg/mL（标准差 [sd]：24.8）。小脑性共济失调 (82.5%) 和脑病 (47.5%) 是最常见的表现特征 (40. 0% 两者都有）；四名患者出现精神病。与精神病相比，存在脑病和/或小脑性共济失调与更高的依非韦伦水平相关（52.1 μg/mL，标准差：24.1 vs 25.0 μg/mL，标准差：17.1）。大多数患者的症状得到缓解，但有 4 名患者 (10.0%) 死亡，1 名患者仍处于共济失调状态。结论 迟发性依非韦伦中毒通常表现为共济失调和脑病，但精神病也可能是首发特征。撤药后的结果很好，但 10.0% 的死亡率令人担忧。指南的最新变化有利于多替拉韦，但许多患者仍在服用依非韦伦，因此了解病情至关重要。这项研究增加了什么