Clinically isolated syndrome (CIS) refers to the initial clinical episode with symptoms suggestive of multiple sclerosis (MS). Due to limited number of long-term follow-up studies, progression pattern from CIS to more advanced stages remains unclear. In the current study, we constructed a Markov model to simulate the natural course of CIS. The model estimated the probabilities of transition from CIS to more advanced disease stages and the duration needed for the progression. The analysis showed: (1) CIS is a solid disease identity: more than 85% of the subjects with a diagnosis of CIS progress to RRMS or more advanced stages within 20 years; (2) the reduction of life expectancy in subjects with CIS is marginal.

中文翻译：

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临床孤立综合征的自然过程：使用马尔可夫模型的纵向分析。

临床孤立综合征（CIS）是指最初的临床发作，其症状提示多发性硬化症（MS）。由于长期随访研究的数量有限，从CIS到更晚期阶段的进展模式仍不清楚。在当前的研究中，我们构建了一个马尔可夫模型来模拟CIS的自然过程。该模型估计了从CIS过渡到更晚期疾病阶段的可能性以及进展所需的持续时间。分析表明：（1）CIS是一种实体疾病身份：在20年内，超过85％的诊断为CIS的患者已发展为RRMS或更晚期。（2）CIS受试者的预期寿命降低是微不足道的。