Danish Dementia Research Centre, Department of Neurology, Copenhagen University Hospital-Rigshospitalet, Copenhagen, Denmark.
National Centre for Register-Based Research, Department of Economics and Business Economics, Aarhus BSS, Aarhus University, Aarhus, Denmark.
Eur J Neurol. 2024 Dec;31(12):e16489. doi: 10.1111/ene.16489. Epub 2024 Oct 6.
Previous studies have reported conflicting results regarding the association between influenza vaccination and dementia. This association was investigated in a nationwide register-based cohort study.
Using nationwide registries, dementia-free adults aged ≥65 years in Denmark from 2002 to 2018 without previous influenza vaccinations were included. Poisson regression facilitated confounder-adjusted comparisons of dementia rates for ever versus never vaccinated, number of vaccinations and within/after 5 years from first vaccination. Sensitivity analyses included stratification on age and sex.
Vaccination during follow-up was associated with a slightly higher rate of dementia when adjusted for sociodemographic factors and comorbidities, both within and after the first 5 years from first vaccination (incidence rate ratio [IRR] 1.04; 95% confidence interval [CI] 1.03-1.05). The rate of dementia decreased with increasing number of vaccinations. The highest rate was amongst those with only one vaccination (IRR 1.14; 95% CI 1.12-1.17) and the rate of dementia was only decreased amongst those with six or more vaccinations (IRR 0.95; 95% CI 0.93-0.97). Applying the same models to control outcomes of hip fracture and cancer resulted in higher rates amongst vaccinated people of 6% and 7%, respectively. Vaccinated people also had a 10% higher mortality rate.
Our results do not support the case for a preventive effect of influenza vaccination on the risk of dementia in the general population, as reported by some previous studies. However, the higher dementia rate amongst vaccinated people found in this study is probably due to residual confounding, indicated by a higher rate for control outcomes and mortality.
既往研究报道流感疫苗接种与痴呆之间的关联结果相互矛盾。本研究通过一项全国范围内基于登记的队列研究对此关联进行了调查。
本研究纳入了 2002 至 2018 年期间丹麦年龄≥65 岁、无既往流感疫苗接种史且无痴呆的成年人作为研究对象。采用泊松回归比较了从未接种疫苗者与全程接种疫苗者、接种疫苗次数与接种后 5 年内痴呆发生率之间的差异。敏感性分析包括按年龄和性别分层。
在调整了社会人口学因素和合并症后，随访期间接种疫苗与痴呆发生率升高相关，无论是在首次接种后 5 年内还是之后（发病率比 [IRR] 1.04；95%置信区间 [CI] 1.03-1.05）。接种疫苗次数越多，痴呆发生率越低。仅接种 1 剂疫苗者的痴呆发生率最高（IRR 1.14；95% CI 1.12-1.17），而接种 6 剂或以上疫苗者的痴呆发生率仅降低（IRR 0.95；95% CI 0.93-0.97）。将相同模型应用于髋部骨折和癌症的控制结局，发现接种者的发生率分别升高 6%和 7%。接种者的死亡率也升高了 10%。
本研究结果不支持既往一些研究报道的流感疫苗接种可降低普通人群痴呆风险的结论。然而，本研究中接种者痴呆发生率较高可能归因于残余混杂，这表现在控制结局和死亡率方面更高的发生率。
