BACKGROUND The concept of improvement of disability recently emerged as a new target in multiple sclerosis (MS) studies since the approval of new potent drugs and for testing drugs for neuroprotection and repair. OBJECTIVE To propose a simple estimator for assessing and comparing the prevalence of improvement over time between groups. METHODS The prevalence of a transient condition takes into account the incidence and the duration of such condition. We propose here the application of a modified Kaplan-Meier estimator to evaluate and compare between groups the prevalence of improvement over time in a cohort of 121 patients treated with autologous hematopoietic stem cell transplantation. RESULTS The prevalence of improvement after 5 years from transplant was 50.3% (95%CI: [38.0-63.0]) in relapsing-remitting patients and 6.5% (95%CI: [0-17.8]) in secondary-progressive patients (p < 0.001). Such a difference wouldn't be evident considering the traditional cumulative probability of improvement at 5 years (55.5% in relapsing-remitting vs 33.4% in secondary-progressive patients, p = 0.10). CONCLUSION This study shows the relevance of a new estimator of prevalence of improvement in MS. This estimator gives simple information on whether a drug can induce a durable improvement in disability and can be considered a potential outcome for trials assessing drugs for neuroprotection or repair.

中文翻译：

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残疾改善作为多发性硬化症试验的潜在结果的普遍性

背景技术自从新的强效药物被批准以及用于测试神经保护和修复药物以来，改善残疾的概念最近成为多发性硬化症（MS）研究的新目标。目的 提出一个简单的估计器，用于评估和比较组间随时间推移的改善流行率。方法 暂时性病症的流行考虑了这种病症的发生率和持续时间。我们在此建议应用改良的 Kaplan-Meier 估计器来评估和比较在 121 名接受自体造血干细胞移植治疗的患者队列中随时间推移的改善流行率。结果 移植后 5 年的改善率在复发缓解患者中为 50.3%（95%CI：[38.0-63.0]）和 6.5%（95%CI：[0-17. 8]）在继发性进展患者中（p < 0.001）。考虑到传统的 5 年累积改善概率（复发缓解患者为 55.5%，继发性进展患者为 33.4%，p = 0.10），这种差异并不明显。结论 本研究显示了新的 MS 改善患病率估计值的相关性。该估计值提供了关于药物是否可以导致残疾的持久改善的简单信息，并且可以被视为评估神经保护或修复药物的试验的潜在结果。结论 本研究显示了新的 MS 改善患病率估计值的相关性。该估计值提供了关于药物是否可以导致残疾的持久改善的简单信息，并且可以被视为评估神经保护或修复药物的试验的潜在结果。结论 本研究显示了新的 MS 改善患病率估计值的相关性。该估计值提供了关于药物是否可以导致残疾的持久改善的简单信息，并且可以被视为评估神经保护或修复药物的试验的潜在结果。