To our knowledge, the present case series represents the largest single-institution study of glioma patients who have contracted SARS-CoV-2. At the time of analysis (July 13, 2022), a total of 88,932,987 cases of COVID-19 had been reported in the United States according to the Centers for Disease Control (CDC) for a total COVID-19 incidence rate of 26.8% [14]. In contrast, a COVID-19 incidence rate of 6.4% was seen in our glioma population. Compared to a national mortality rate of 1.1%, no patients in our population died from COVID-19-related causes. The authors of a recent COVID-19 case series in primary brain tumor patients from a Dutch national database reported that 63% of patients had a severe course of COVID-19 and 13% had a fatal outcome related to COVID-19 or its complications [15]. That study, however, was enriched for inpatient cases, thus not likely representing real-world incidence. Our data can also be compared to the CCC-19 dataset where authors reported a 30-day case fatality rate of 11% among patients with all types of cancer [16].
Hospitalization rate in our population was 17.2% which is higher than the national average admission rate of 5.6% although this may reflect that cancer patients are more likely than other patients to seek medical care and be admitted out of caution [14]; moreover, only 6.9% of patients qualified for and received COVID-19-specific treatment during admission. Of note, our hospitalization rate was much lower than that published in the CCC-19 database (55%) [16]. Although KPS declined in 20.7% of patients after contracting COVID-19, this functional decline is not unexpected in the natural history of glioma. On individual review of charts, this decline was felt to be due to disease progression as opposed to symptomatic sequelae from COVID-19 infection.
In summary, compared to the national average, our population of glioma patients had lower incidence rates of COVID-19, did not appear to be prone to a severe illness course, nor demonstrated an increased mortality rate. These findings suggest that glioma patients are not at increased risk of contracting or experiencing worse outcomes from COVID-19 infection. Several factors may have contributed to these results. First, anecdotally speaking, our neuro-oncology patient population tends to have high vaccination rates against SARS-CoV-2. It would reason that non-vaccination would be enriched in the current population of those who contracted COVID-19 (in this case 48.3% of patients had not yet received a vaccine). However, it is important to note that by the end of analysis, all but one patient had eventually become vaccinated. This fact might also explain the relatively low rate of COVID-19 re-infection (one patient, 3.4%).
Our study has several limitations. First, this was a retrospective analysis, which confers its own limitations. The limited sample size precludes ability to make meaningful statistical comparisons; however, we reiterate that this study currently represents the largest single-institution study of its kind. Single-institution studies are not necessarily generalizable, although they have the benefit of providing in-depth retrospective analysis of cases in a real-world population and are less likely than national databases to be skewed towards inpatient populations. In this case, single institution analysis also allows for a relatively standardized set of practices for both glioma and COVID-19 management.
COVID-19 represents an under-studied field within the neuro-oncological community. With COVID-19 variants continuing to impact the world, we hope that our results provide insight as to how this disease affects glioma patients and will drive future research in this important topic.