BACKGROUND A period of diagnostic uncertainty often characterizes the clinical transition from relapsing to secondary progressive multiple sclerosis (SPMS). OBJECTIVE The aim of this study was to describe the length of time required to reclassify relapsing-remitting MS (RRMS) patients who have clinically transitioned to SPMS (diagnosis uncertainty). METHODS This is a retrospective multicenter cohort study conducted in Argentina, identifying in every center all patients with diagnosis of MS who transitioned from RRMS to SPMS during the follow-up. We identified the dates of the last definitive RRMS and first definitive SPMS diagnoses for diagnostic uncertainty. The time required to reclassify RRMS who transitioned to SPMS and the time from disease onset to reclassify SPMS were calculated using the Kaplan-Meier method. RESULTS A total of 170 patients were included, where the mean age at disease onset (first symptom) was 36 ± 6 years; the length of time required to reclassify RRMS patients who transitioned to SPMS was 3.3 ± 1.1 years (range = 1-7 years); and the time from disease onset to classify SPMS was 19.4 ± 8.5 years (range = 16-35 years). CONCLUSION A period of diagnostic uncertainty regarding the transition from RRMS to SPMS was present in many of our patients, with a mean time of 3.3 years.

中文翻译：

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向继发性进行性多发性硬化过渡期间的诊断不确定性：阿根廷的多中心研究

背景诊断不确定期通常表征从复发到继发性进行性多发性硬化症(SPMS)的临床转变。目的 本研究的目的是描述重新分类已临床转变为 SPMS（诊断不确定性）的复发缓解型 MS (RRMS) 患者所需的时间长度。方法 这是一项在阿根廷进行的回顾性多中心队列研究，在每个中心确定所有在随访期间从 RRMS 转变为 SPMS 的 MS 诊断患者。我们确定了最后一次确定的 RRMS 和第一次确定的 SPMS 诊断的日期，以确定诊断的不确定性。使用 Kaplan-Meier 方法计算重新分类过渡到 SPMS 的 RRMS 所需的时间以及从疾病发作到重新分类 SPMS 的时间。结果 共纳入 170 名患者，其中发病（首发症状）的平均年龄为 36 ± 6 岁；对转为 SPMS 的 RRMS 患者进行重新分类所需的时间为 3.3 ± 1.1 年（范围 = 1-7 年）；从发病到分类 SPMS 的时间为 19.4 ± 8.5 年（范围 = 16-35 年）。结论 我们的许多患者存在一段关于从 RRMS 到 SPMS 过渡的诊断不确定期，平均时间为 3.3 年。