BACKGROUND AND OBJECTIVES All 4 previous nationwide surveys of multiple sclerosis (MS) in Japan were conducted before the discovery of anti-aquaporin-4 (AQP4) antibodies; thus, neuromyelitis optica spectrum disorder (NMOSD) was included in MS, as optic-spinal MS. We aimed to clarify the epidemiologic features and trends of MS and NMOSD in Japan separately using a fifth nationwide survey. METHODS The primary survey, in which a questionnaire was sent to 3,799 selected departments (including neurology/internal medicine, pediatrics, and ophthalmology), explored the estimated number and prevalence of patients with MS or NMOSD in 2017, and the secondary survey collected detailed characteristics of the patients using a second questionnaire. RESULTS The response rates for the primary and secondary surveys were 60.1% and 53.9%, respectively. The estimated total number of patients with MS or NMOSD was 24,800, 2.5-fold higher than that in the fourth survey in 2003. The crude prevalence was 19.6 per 100,000 patients (14.2 for MS and 5.4 for NMOSD), compared with 7.7 per 100,000 patients in the fourth survey. Patients with MS showed milder disability (median Expanded Disability Status Scale [EDSS] score: 2.0 [interquartile range 1.0-4.5] vs 2.5 [1.0-6.0]), decreased secondary progression (8.5% vs 15.2%), and increased usage of disease-modifying drugs (63.7% vs 37.2%) compared with those with conventional MS in the fourth survey. The proportions of oligoclonal bands and Barkhof criteria fulfillment on MRI, which are features of classical MS, increased with advancing year of birth. Patients with NMOSD also showed less disability and shorter disease duration than patients with optic-spinal MS in the fourth survey (EDSS score: 3.5 [2.0-5.5] vs 3.8 [2.0-6.0]; disease duration: 8.0 [3.9-14.8] vs 10.0 [5.0-16.0]). Among patients with NMOSD, disability was exacerbated by a history of longitudinally extensive spinal cord lesions and anti-AQP4 antibody positivity, which both decreased with advancing year of birth. DISCUSSION The prevalences of MS (particularly with classical features) and NMOSD have been increasing in Japan, suggesting the contribution of environmental factors. However, disabilities in patients with MS and NMOSD have been mitigated. Extensive usage of various disease-modifying drugs could be a factor contributing to this disability mitigation in MS.

中文翻译：

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第五次全国调查显示日本多发性硬化症和视神经脊髓炎谱系疾病的患病率和残疾情况。


背景和目标 日本之前所有 4 次多发性硬化症 （MS） 全国调查都是在发现抗水通道蛋白 4 （AQP4） 抗体之前进行的;因此，视神经脊髓炎谱系疾病 （NMOSD） 作为视脊髓 MS 包含在 MS 中。我们旨在通过第五次全国性调查分别阐明日本 MS 和 NMOSD 的流行病学特征和趋势。方法 初步调查向 3,799 个选定科室（包括神经内科、儿科和眼科）发送了一份问卷，探讨了 2017 年 MS 或 NMOSD 患者的估计人数和患病率，二次调查使用第二份问卷收集了患者的详细特征。结果 主要和次要调查的回复率分别为 60.1% 和 53.9%。估计 MS 或 NMOSD 患者总数为 24,800 人，比 2003 年第四次调查高出 2.5 倍。粗患病率为每 100,000 名患者 19.6 例（MS 为 14.2 例，NMOSD 为 5.4 例），而第四次调查为每 100,000 名患者 7.7 例。在第四次调查中，与传统 MS 患者相比，MS 患者表现出较轻的残疾（扩展残疾状态量表 [EDSS] 评分中位数：2.0 [四分位距 1.0-4.5] vs 2.5 [1.0-6.0]），继发性进展减少（8.5% 对 15.2%），以及疾病缓解药物的使用增加（63.7% 对 37.2%）在第四次调查中。MRI 上寡克隆带和 Barkhof 标准满足的比例是经典 MS 的特征，随着出生年份的增加而增加。在第四次调查中，与视脊髓 MS 患者相比，NMOSD 患者的残疾程度也较低且病程较短（EDSS 评分：3.5 [2.0-5.5] vs 3.8 [2.0-6.0];病程：8.0 [3.9-14.8] 与 10.0 [5.0-16.0]）。在 NMOSD 患者中，纵向广泛性脊髓病变病史和抗 AQP4 抗体阳性加剧了残疾，这两种情况都随着出生年份的增加而降低。讨论 MS （尤其是具有经典特征的） 和 NMOSD 在日本的患病率一直在增加，这表明环境因素的贡献。然而，MS 和 NMOSD 患者的残疾已经得到缓解。广泛使用各种疾病缓解药物可能是导致 MS 残疾缓解的一个因素。