The Institute for Clinical Evaluative Sciences, Toronto, Canada.
Vaccine. 2010 Dec 16;29(2):240-6. doi: 10.1016/j.vaccine.2010.10.049. Epub 2010 Oct 31.
The objective of this study was to evaluate the effectiveness of influenza vaccines in reducing all-cause mortality among community-dwelling elderly. We included 25,922 Ontario residents over age 65 who responded to population health surveys. After full adjustment, influenza vaccination was associated with a statistically significant reduction in all-cause mortality during influenza seasons (hazard ratio (HR)=0.61; 95% CI 0.47-0.79). Contrary to expectations, statistically significant associations between influenza vaccination and mortality were also observed during periods preceding (HR=0.55; 95% CI 0.40-0.75) and following (HR=0.74; 95% CI 0.59-0.94) influenza seasons, indicating the presence of residual confounding. Adjustment for functional status indicators, excluding individuals with high one-year predicted mortality at baseline, and moving the start date of follow-up failed to eliminate the refractory confounding. Since observational studies are prone to bias, future efforts to estimate vaccine effectiveness in the elderly should strive to minimize bias through improved data quality, novel data sources, and/or new analytical techniques.
本研究旨在评估流感疫苗在降低社区居住的老年人群全因死亡率方面的效果。我们纳入了 25922 名年龄在 65 岁以上、对人群健康调查做出回应的安大略省居民。经过充分调整后，流感疫苗接种与流感季节全因死亡率的显著降低相关（风险比（HR）=0.61；95%置信区间 0.47-0.79）。出乎意料的是，在流感季节之前（HR=0.55；95%置信区间 0.40-0.75）和之后（HR=0.74；95%置信区间 0.59-0.94），流感疫苗接种与死亡率之间也存在统计学上显著的关联，表明存在残余混杂。调整功能状态指标、排除基线时一年预测死亡率高的个体，以及更改随访开始日期，均未能消除顽固混杂。由于观察性研究容易出现偏倚，未来评估老年人疫苗效果的研究应通过提高数据质量、利用新数据源和/或新分析技术，努力将偏倚最小化。
