School of Public Health, The University of Hong Kong, Level 6, Core F, Cyberport 3, 100 Cyberport Road, Pokfulam, Hong Kong.
Comput Math Methods Med. 2013;2013:637064. doi: 10.1155/2013/637064. Epub 2013 Feb 21.
The total number of influenza cases with medical attendance has been estimated from sentinel surveillance data in Japan under a random sampling assumption of sentinel medical institutions among the total medical institutions. The 2009 pandemic offered a research opportunity to validate the sentinel-based estimation method using the estimated proportion of infections measured by the population-wide seroepidemiological survey employing hemagglutinin inhibition (HI) assay. For the entire population, we estimated the age-standardized proportion of infections at 28.5% and 23.5% using cut-off values of HI titer at 1 : 20 and 1 : 40, respectively. Investigating the age profiles, we show that the estimated influenza-like illness (ILI) cases with medical attendance exceeded the estimated infections among those aged from 0 to 19 years, indicating an overestimation of the magnitude by sentinel-based estimation method. The ratio of estimated cases to estimated infections decreased as a function of age. Examining the geographic distributions, no positive correlation was identified between the estimated cases and infections. Our findings indicate a serious technical limitation of the so-called multiplier method in appropriately quantifying the risk of influenza due to limited specificity of ILI and reporting bias. A seroepidemiological study should be planned in advance of a pandemic.
基于哨点医疗机构在全部医疗机构中随机抽样的假设，从日本的哨点监测数据中估算了有就医记录的流感病例总数。2009 年的大流行提供了一个使用人群血清流行病学调查（采用血凝抑制（HI）试验）测量的感染比例进行验证基于哨点的估计方法的研究机会。对于整个人群，我们使用 HI 滴度的截断值分别为 1:20 和 1:40，估计感染的年龄标准化比例分别为 28.5%和 23.5%。研究年龄分布表明，估计有就医记录的流感样疾病（ILI）病例数超过了 0 至 19 岁人群的估计感染数，表明基于哨点的估计方法高估了疾病的严重程度。估计病例数与估计感染数的比值随年龄的增加而降低。检查地理分布，未发现估计病例数与感染数之间存在正相关关系。我们的研究结果表明，由于 ILI 的特异性有限和报告偏倚，所谓的乘数法在适当量化流感风险方面存在严重的技术限制。应在大流行之前预先计划进行血清流行病学研究。
