St. Joseph's Health Centre, Toronto, Ontario, Canada.
St. Michael's Hospital, Toronto, Ontario, Canada.
PLoS One. 2019 Jan 15;14(1):e0210833. doi: 10.1371/journal.pone.0210833. eCollection 2019.
Adverse events following immunization (AEFIs) are unwanted or unexpected health outcomes following vaccination, which may or may not be causally-linked to vaccines. AEFI reporting is important to post-marketing vaccine safety surveillance and has the potential to identify new or rare AEFIs, show increases in known AEFIs, and help to maintain public confidence in vaccine programs. Knowledge of the expected incidence (i.e. background rate) of a possible AEFI is essential to the investigation of vaccine safety signals. We selected three rarely reported AEFIs representing the spectrum of causal association with vaccines, from proven (immune thrombocytopenia [ITP]) to questioned (Kawasaki disease [KD]) to unsubstantiated (multiple sclerosis [MS]) and determined their background rates.
We extracted data on hospitalizations (CIHI Discharge Abstract Database) for ITP, KD, and MS among Ontario children for the period 2005 to 2014 from IntelliHEALTH. As ITP can be managed without hospitalization, we also extracted emergency department (ED) visits from the CIHI National Ambulatory Care Reporting System. For all conditions, we only counted the first visit and if the same child had both an ED visit and a hospitalization for ITP, only the hospitalization was included. We calculated rates by year, age group and sex using population estimates from 2005-2014, focusing on age groups within the Ontario immunization schedule around vaccine(s) of interest.
Per 100,000 population, annual age-specific incidence of ITP in children age 1 to 7 years ranged from 8.9 to 12.2 and annual incidence of KD in children less than 5 years ranged from 19.1 to 32.1. Average annualized incidence of adolescent (11-17 years) MS across the study period was 0.8 per 100,000.
Despite limitations, including lack of clinical validation, this study provides an example of how health administrative data can be used to determine background rates which may assist with interpretation of passive vaccine safety surveillance.
疫苗接种后不良反应（AEFI）是接种疫苗后出现的非预期或意外健康结果，这些反应可能与疫苗有关，也可能无关。AEFI 报告对于疫苗上市后安全性监测非常重要，有可能发现新的或罕见的 AEFI，显示已知 AEFI 的增加，并有助于维持公众对疫苗计划的信心。了解可能的 AEFI 的预期发生率（即背景发生率）对于疫苗安全性信号的调查至关重要。我们选择了三种罕见报告的 AEFI，代表了与疫苗因果关系的范围，从已证实（免疫性血小板减少症 [ITP]）到有疑问（川崎病 [KD]）到未证实（多发性硬化症 [MS]），并确定了它们的背景发生率。
我们从 IntelliHEALTH 中提取了 2005 年至 2014 年安大略省儿童因 ITP、KD 和 MS 住院（CIHI 出院摘要数据库）的数据。由于 ITP 可以在不住院的情况下得到治疗，我们还从 CIHI 国家门诊护理报告系统中提取了急诊就诊数据。对于所有情况，我们只计算了第一次就诊，如果同一个孩子既有急诊就诊又有 ITP 住院，只包括住院治疗。我们使用 2005-2014 年的人口估计数，按年、年龄组和性别计算发病率，重点关注与感兴趣疫苗（s）的安大略省免疫计划内的年龄组。
每 10 万人中，1 至 7 岁儿童的 ITP 年龄特异性发病率为每年 8.9 至 12.2，5 岁以下儿童的 KD 发病率为每年 19.1 至 32.1。整个研究期间，青少年（11-17 岁）MS 的平均年化发病率为每 10 万人 0.8。
尽管存在局限性，包括缺乏临床验证，但本研究提供了一个如何使用健康管理数据来确定背景发生率的示例，这可能有助于解释被动疫苗安全性监测。
