Decreased incidence of febrile neutropenia in Michigan following masking and social distancing orders for the COVID-19 pandemic: A population based cohort study

Abstract

Background: It has been theorized that 75%-80% of febrile neutropenia (FN) is caused by endogenous pathogens, while up to 20% of cases are thought to be caused by a viral infection. It is unknown if precautions such as masking and social distancing reduce the risk of FN in susceptible populations.

Aim: To determine whether coronavirus disease 2019 (COVID-19) infection mitigation efforts, namely masking and social distancing, were associated with a reduction in the incidence of FN.

Methods: This was a retrospective population based cohort study comparing the incidence of FN in the 13 mo prior to (Year 0) and 13 mo following (Year 1) the public health executive orders (PHEO) in Michigan. Data was queried for all emergency department (ED) visits from April 1, 2019 to March 31, 2021 from the National Syndromic Surveillance Program, a program which collects data that is voluntarily submitted by approximately 89% of Michigan EDs. The primary study outcome was the incidence of FN as a proportion of ED visits in the 13-mo before and 13-mo after COVID-19 mitigations efforts, namely masking and social distancing. We hypothesized that there would be a significant decrease in the incidence of FN in the period following the PHEO aimed at reducing the spread of the severe acute respiratory syndrome coronavirus 2 virus.

Results: There was a total of 8979221 total ED visits captured during the study period. In Year 0 there were 5073081 recorded ED visits and 3906140 in Year 1. There was a significant reduction in the proportion of total ED visits with a diagnosis of FN, decreasing 13.3% across periods (0.15% vs 0.13%, P = 0.036). In patients with a hematologic malignancy a more impressive reduction in the incidence of FN was evident following PHEO (22% vs 17%, P = 0.02).

Conclusion: We found a significant association between social distancing and mask guidelines implemented on a large public scale with decreased rates of FN, particularly in those with a hematologic malignancy. These findings may be useful in the design of future research and recommendations regarding the prevention of FN.

Keywords: COVID-19; Febrile neutropenia; Hematology; Malignancy; Public health; SARS-CoV-2.

Figure 1

Incidence of febrile neutropenia in patients with an associated diagnosis of hematologic malignancy compared to those without a diagnosis of hematologic malignancy. Patients with a diagnosis of a hematologic malignancy were significantly more likely to be febrile than those without a diagnosis of hematologic malignancy in Year 0 (21.2% vs 29.3%, P < 0.0001). This difference was not seen after implementation of public health guidelines in Year 1 (20.2% vs 23.8%, P = 0.12).