Decreased Incidence of Michigan Emergency Department Visits for Febrile Neutropenia Observed After Public Health Measures for the COVID-19 Pandemic

Importance: Masking and social distancing appear to decrease the of febrile neutropenia in susceptible populations, especially among patients with hematologic malignancies.Objective: To determine whether COVID-19 infection mitigation efforts, namely masking and social distancing, results in a reduction in the incidence of febrile neutropenia.Design: This was a retrospective cohort study comparing the incidence of FN in the 13 months prior to (Year 0) and 13 months following (Year 1) the public health executive orders (PHEO) in Michigan. Data voluntarily submitted by Michigan emergency departments to the National Syndromic Surveillance Program (NSSP) was queried for all ED visits from April 1st, 2019 to March 31st, 2021.Setting: Population based study.Participants: A population-based sample of patients who reported to a Michigan emergency department and on whom data was captured.Intervention(s): Population based masking and social distancing.Main Outcome(s) and Measure(s): The primary study outcome was the incidence of FN as a proportion of emergency visits in the 13-months before and 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 public health executive orders aimed at reducing the spread of the COVID-19 virus.Results: There was a total of 8,979,221 total ED visits captured during the study period. In Year 0 there were 5,073,081 recorded ED visits and 3,906,140 in Year 1, a decrease of 23%. 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 the incidence of FN was significantly lower in the period following PHEO (22% vs 17%, p=0.02, Table 2).Conclusions and Relevance: Our study 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 clinical trials as well as informing future recommendations for the prevention of FN.