Supplementary Material for: Secular trends of the incidence of encephalitis and outcomes of postencephalitic epilepsy in Taiwan: A nationwide population-based study

Background: Encephalitis can lead to significant disability among survivors. Up-to-date estimates of encephalitis incidence and the risk of postencephalitic epilepsy (PE) are crucial for informing health policy.
Methods: We used the National Taiwan Insurance Research Database to estimate the standardized incidence of encephalitis for each year from 2003 to 2017. We analyzed PE among these cases.
Results: From 2003 to 2017, the age- and sex-standardized incidence of encephalitis increased from 5.95 (95% confidence interval [CI]: 5.61–6.28) to 10.46 (95% CI: 10.04–10.87) per 100,000 person-years, with an annual percentage change of 1.6% (1.1–2.2, p < 0.05). However, yearly variation was observed. The incidence was consistently higher in patients under 18 years than in those aged ≥ 18 years throughout the study period. In 2017, the highest annual incidence was seen in adults aged ≥ 70 years and in children aged 1–4 years. Approximately 20% of the survivors developed PE within 5 years, with the highest risk observed in infants under 1 year of age.
Conclusions: The overall incidence of encephalitis in Taiwan increased from 2003 to 2017. Pediatric patients, particularly those under 1 year of age, are more vulnerable to encephalitis and its long-term complications, including PE, compared to adults, except for those aged ≥ 70 years.

研究背景：脑炎可导致幸存者出现严重残疾。脑炎发病率及脑炎后癫痫（postencephalitic epilepsy, PE）发病风险的最新估算数据，对卫生政策制定具有关键指导价值。研究方法：本研究采用中国台湾地区全民健康保险研究数据库（National Taiwan Insurance Research Database），估算2003至2017年各年度脑炎的年龄-性别标化发病率，并对该研究队列中脑炎后癫痫的发生情况进行分析。研究结果：2003至2017年间，脑炎的年龄-性别标化发病率从每10万人年5.95（95%置信区间[CI]：5.61~6.28）升至10.46（95% CI：10.04~10.87），年度百分比变化为1.6%（1.1~2.2，P<0.05），且各年度发病率存在波动。整个研究周期内，18岁以下患者的脑炎发病率始终高于18岁及以上人群。2017年，70岁及以上成人与1~4岁儿童的脑炎发病率达到峰值。约20%的脑炎幸存者在发病后5年内出现脑炎后癫痫，其中1岁以下婴儿的发病风险最高。研究结论：2003至2017年，中国台湾地区脑炎的总体发病率呈上升态势。与成人（70岁及以上人群除外）相比，儿科患者，尤其是1岁以下婴儿，更易罹患脑炎及其包括脑炎后癫痫在内的长期并发症。