Shivarov Velizar, Grigorova Denitsa, Yordanov Angel
Department of Experimental Research, Medical University Pleven, 5800 Pleven, Bulgaria.
Department of Probability, Operations Research and Statistics, Faculty of Mathematics and Informatics, Sofia University, 1504 Sofia, Bulgaria.
Healthcare (Basel). 2023 Sep 20;11(18):2594. doi: 10.3390/healthcare11182594.
The COVID-19 pandemic has led to millions of documented deaths worldwide, with diverse distribution among countries. Surprisingly, Bulgaria, a middle-income European Union member state, ranked highest in COVID-19 mortality. This study aims to assess whether Bulgarian cancer patients experienced a higher relative risk (RR) of death compared to the general Bulgarian population during the pandemic.
Data from the Bulgarian National Statistical Institute and the Bulgarian National Cancer Registry were analyzed to estimate monthly RR of death in cancer patients compared to the general population before and during the first two years of the pandemic. The impact of the COVID-19 waves and predominant SARS-CoV-2 variants on RR was evaluated on various cancer types and age groups using a multiple linear regression approach.
During the COVID-19 waves, both the general population and cancer patients experienced a significant increase in mortality rates. Surprisingly, the RR of death in cancer patients was lower during pandemic waves. The results from the statistical modeling revealed a significant association between the COVID-19 waves and reduced RR for all cancer patients. Notably, the effect was more pronounced during waves associated with the Alpha and Delta variants. The results also showed varying impacts of the COVID-19 waves on RR when we analyzed subsamples of data grouped depending on the cancer type, age and sex.
Despite increased overall mortality in Bulgarian cancer patients during the pandemic, the RR of death was lower compared to the Bulgarian general population, indicating that protective measures were relatively effective in this vulnerable group. This study underscores the importance of implementing and encouraging preventive measures, especially in cancer patients, to mitigate the impact of future viral pandemics and reduce excess mortality.
新冠疫情已导致全球数百万例有记录的死亡，各国分布情况各异。令人惊讶的是，保加利亚这个中等收入的欧盟成员国在新冠死亡率方面排名最高。本研究旨在评估保加利亚癌症患者在疫情期间与保加利亚普通人群相比是否经历了更高的死亡相对风险（RR）。
分析了保加利亚国家统计局和保加利亚国家癌症登记处的数据，以估计疫情头两年之前和期间癌症患者与普通人群相比的每月死亡RR。使用多元线性回归方法评估了新冠疫情波次和主要的新冠病毒变异株对RR的影响，涉及各种癌症类型和年龄组。
在新冠疫情波次期间，普通人群和癌症患者的死亡率均显著上升。令人惊讶的是，在疫情波次期间癌症患者的死亡RR较低。统计建模结果显示，新冠疫情波次与所有癌症患者RR降低之间存在显著关联。值得注意的是，在与阿尔法和德尔塔变异株相关的波次中，这种影响更为明显。当我们分析根据癌症类型、年龄和性别分组的数据子样本时，结果还显示了新冠疫情波次对RR的不同影响。
尽管保加利亚癌症患者在疫情期间总体死亡率有所上升，但与保加利亚普通人群相比，死亡RR较低，这表明保护措施在这一弱势群体中相对有效。本研究强调了实施和鼓励预防措施的重要性，尤其是在癌症患者中，以减轻未来病毒大流行的影响并降低超额死亡率。
