Ericka Samantha Teleg, MD

Lazcano U, Cuadrado-Godia E, Grau M, Subirana I, Martinez-Carbonell E, Boher-Massaguer M, Rodríguez-Campello A, Giralt-Steinhauer E, Fernández-Pérez I, Jiménez-Conde J, et al. Increased COVID-19 Mortality in People With Previous Cerebrovascular Disease: A Population-Based Cohort Study. Stroke. 2021.

The COVID-19 pandemic has shaped and changed the diagnostic, treatment, and management landscape in stroke healthcare throughout the world. The authors of this study emphasized several important points in the beginning in defining their research question: Is previous stroke an independent risk factor for mortality after COVID-19?

At the start, COVID-19 had stroke specialists and other health care specialists analyze mortality and risk of cerebrovascular disease in a population-based cohort in a prospective methodology. This is the strength of this article; using a prospective methodology to answer a research question such as theirs is a challenge since the pandemic landscape is continuously evolving. Several other studies utilized hospital cohorts.

They have laid out the following limitations of what we currently know and that is important for the audience to discern. First, hospital cohorts used in several studies mostly are retrospective in nature, and there are only a few prospective population-based studies. The previous findings in these retrospective studies cannot gather enough information that is reflective of the general population. Second, there are now heterogenous results in terms of the association of previous stroke and mortality due to COVID-19. Third, stroke has not been analyzed as an independent risk factor in the setting of COVID-19 infection. Fourth, subtypes of stroke in the setting of COVID-19 have not been ascertained, beyond initial case series of increased large vessel occlusions.

Their secondary aim is straightforward and that is to determine if this association is maintained within different sexes, age groups and stroke subtypes.

This a population-based, prospective cohort study. They used a linked health administration database that is based in Catalonia, Spain. Their timeline included cases from February 1, 2020 to July 31, 2020. However, these included cases were observed until December 31, 2020. The Catalan Service of Epidemiological Surveillance (SUVEC), which had COVID-19 positive cases within the period, utilized all available tests for COVID-19 detection. They included all cases that were positive within the population of Catalonia and included cases that were both symptomatic and asymptomatic and tracked the degree of illness. They used the term previous stroke as defined by the ICD code, including the subtypes, and included all comorbidities that have been associated with COVID-19, older age, obesity, smoking status, and previous cancer within five years. They also included information regarding socioeconomic status from the central registry. Deprivation index was not associated with mortality. In previous studies, a poor socioeconomic status predicted higher mortality due to poor baseline health status. Their primary outcomes included mortality after COVID-19, defined as any death occurring after COVID-19 positive infection, defined by death occurring during the study period. Data regarding deaths were obtained from local health registries.

In this study, their results reflect an analysis that covered 98% of the population in Catalonia, Spain. There were 91,629 COVID-19 cases from February 1, 2020 to July 31, 2020. This is the first study that was able to analyze the influence of each stroke subtype in the whole COVID-19 population. Together with this, previous cerebrovascular disease showed recent stroke had a higher risk of mortality than late stroke.

In terms of the distribution of stroke subtypes, cases with previous stroke were 5,752 and that is 6.2%; and most were ischemic strokes (3883 (67.6%)), followed by TIA (1237 (21.5%)), combined strokes (255, (4.43%)), hemorrhagic strokes (9203 (3.53%)), and SAH (170 (2.96%)). The cumulative incidence of mortality was higher in cases with previous stroke, globally, and for each subgroup, with a higher mortality incidence in ischemic, hemorrhagic and combined groups. Mortality risk is not increased in patients with previous TIA or SAH. For age, their results reflect previous stroke was associated with mortality in the age group <60 years, and the 60 to 79 years age group, but not in the older >80 years age group.

They have highlighted the public health implication of COVID-19 vaccination programs for younger than 80 years age group with previous stroke, not prioritized for vaccination, as a potential contributor for the age-group related results. This study provides comprehensive data analysis on demographics, comorbidities, and socioeconomic status of all COVID-19 cases. Study limitations include lack of ethnicity background evaluation, exclusion of  asymptomatic cases, and  final cause of death was not captured as part of this analysis.  

Overall, this study showed previous cerebrovascular disease was associated with higher mortality risk during the COVID-19 pandemic in Catalonia, Spain.