Am J Epidemiol. 2013 Oct 15;178(8):1313-8. doi: 10.1093/aje/kwt120. Epub 2013 Aug 26.
The impact of influenza pandemics might be overestimated; the published studies of years of life lost (YLL) have typically ignored the presence of underlying chronic conditions or health risk behaviors in most deaths. We used data on deaths involving laboratory-confirmed 2009 influenza A(H1N1) virus infection that occurred between April 2009 and May 2010 in Hong Kong, China, to adjust for these underlying risk factors. Life expectancy was corrected with hazard-based modifications to the life tables. The excess hazards posed by underlying risk factors were added to the "baseline" age-specific hazards in the local life tables to reflect the life expectancy associated with each underlying risk factor. Of 72 deceased persons with laboratory-confirmed 2009 influenza A(H1N1) virus infection, 56% had underlying risk factors. We estimated that the 2009 pandemic was associated with 1,540 (95% confidence interval: 1,350, 1,630) YLL after adjustment for age and underlying risk factors. This figure is approximately 25% lower than the YLL estimate of 2,080 derived after adjustment for age but not for risk factors. Our analysis demonstrates the potential scale of bias in YLL estimation if underlying risk factors are ignored. The estimation of YLL with correction for underlying risk factors in addition to age could also provide a framework for similar calculations elsewhere.
流感大流行的影响可能被高估了；已发表的生命损失年（YLL）研究通常忽略了大多数死亡病例中潜在的慢性疾病或健康风险行为。我们使用了 2009 年 4 月至 2010 年 5 月期间在中国香港发生的实验室确诊 2009 年甲型 H1N1 流感病毒感染死亡病例的数据，以调整这些潜在的风险因素。通过对生命表进行基于风险的修正，来校正预期寿命。将潜在风险因素带来的额外风险加到当地生命表的“基线”年龄特异性风险中，以反映与每个潜在风险因素相关的预期寿命。在 72 名实验室确诊的 2009 年甲型 H1N1 流感病毒感染死亡病例中，有 56%的病例存在潜在的风险因素。我们估计，在调整年龄和潜在风险因素后，2009 年大流行与 1540 例（95%置信区间：1350 例，1630 例）YLL 有关。这一数字比调整年龄但不调整风险因素后的 YLL 估计值 2080 例低约 25%。我们的分析表明，如果忽略潜在的风险因素，在 YLL 估计中存在潜在的偏差规模。除年龄外，通过对潜在风险因素进行校正来估计 YLL，也可为其他地方的类似计算提供框架。
