Cross-sectional case-control studies (Blue)
Read on for our pick of COVID-19-related cross-sectional case control studies from the scientific press for April 2023:
- The association between COVID-19 and cognitive performance: A Mendelian randomization analysis
- Incidence of Guillain-Barré syndrome in South Korea during the early COVID-19 pandemic
The association between COVID-19 and cognitive performance: A Mendelian randomization analysis
People with COVID-19 had poorer general cognitive functioning compared to people without COVID-19. The causal link between COVID-19 and cognitive impairment is still unknown. Mendelian randomization (MR) is a statistical approach based on genome-wide association studies (GWAS) to construct instrumental variables (IVs) and can effectively bring down the confounding bias of environmental or other disease factors, because alleles are randomly assigned to offspring.
The authors of this article found a consistent evidence that cognitive performance was causally associated with COVID-19; this suggests that people with better cognitive performance are less likely to be infected with COVID-19. The reverse MR analysis treating COVID-19 as the exposure and cognitive performance as the outcome demonstrated an insignificant association, indicating the unidirectionality of the relationship. The authors concluded underlying that their study provided credible evidence that cognitive performance has an impact on COVID-19. Future research should focus on long-term impact of cognitive performance on COVID-19.
Ran S, Yao J, Liu B. The association between COVID-19 and cognitive performance: A Mendelian randomization analysis. Alzheimers Dement. 2023 Mar 11. doi: 10.1002/alz.13017. Epub ahead of print. PMID: 36905350.
Incidence of Guillain-Barré syndrome in South Korea during the early COVID-19 pandemic
Guillain-Barré syndrome (GBS) is an immune-mediated polyradiculoneuropathy, often triggered by infection. The authors of this article aimed to investigate how the incidence of GBS changed in the early stages of the coronavirus 2019 (COVID-19) pandemic when nationwide infections declined due to non-pharmaceutical interventions. In particular they conducted a nationwide population-based retrospective GBS cohort study using data from the Health Insurance Review and Assessment Service of Korea. Patients with new-onset GBS were defined as those who were first hospitalized between 1 January 2016 and 31 December 2020 with an International Classification of Disease, 10th Revision code, for GBS (G61.0) as a primary diagnosis. The incidence of GBS in the pre-pandemic years (2016-2019) was compared with that in the first pandemic year (2020). Nationwide epidemiological data for infections were collected from the national infectious disease surveillance system. A correlation analysis was performed to determine the incidence of GBS and nationwide trends of various infections.
Overall, 3,637 new-onset GBS cases were identified. The age-standardized incidence of GBS in the first pandemic year was 1.10 (95% confidence interval, 1.01-1.19) per 100,000 persons. Compared to the first pandemic year, the incidence of GBS during the pre-pandemic years (1.33-1.68/100,000 persons/year) was significantly higher, with incidence rate ratios of 1.21-1.53 (P < 0.001). Nationwide cases of upper respiratory viral infections were significantly reduced in the first pandemic year; however, Campylobacter infections peaked in the summer of the pandemic. The nationwide epidemiology of parainfluenza virus, enterovirus, and Campylobacter infections correlated positively with GBS incidence. The authors concluded that the overall GBS incidence decreased in the early stages of the COVID-19 pandemic, which can be attributed to the dramatic reduction in viral illnesses due to public measures.
Choi SA, Hwang J, Lim BC, Chae SA. Incidence of Guillain-Barré syndrome in South Korea during the early COVID-19 pandemic. Front Neurol. 2023 Feb 21;14:1125455. doi: 10.3389/fneur.2023.1125455. PMID: 36895908; PMCID: PMC9989167.
