key: cord-0893015-vmuegsqa authors: Lam, Regina W; Inselman, Jonathan W; Jeffery, Molly M; Maddux, Jacob T; Rank, Matthew A title: National decline in asthma exacerbations in US during COVID19 pandemic date: 2021-09-25 journal: Ann Allergy Asthma Immunol DOI: 10.1016/j.anai.2021.09.017 sha: 13aedc18fd091bb2c9eee6571633fd2c2e0994ac doc_id: 893015 cord_uid: vmuegsqa nan The authors report no conflicts of interest. Funding: National Institutes of Health, National Heart, Lung, and Blood Institute (NIH R21 HL140287) and the Mayo Clinic Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery. Infection with COVID-19 has led to over 4 million deaths worldwide, challenging our healthcare systems. At the same time, it has also led to an increased use of non-pharmaceutical interventions (NPIs) to minimize disease spread. COVID-era NPIs such as physical distancing are associated with an unprecedented decrease of non-COVID-19 viral respiratory diseases. [1] [2] [3] Viral respiratory infections are a common cause for asthma exacerbations that lead to ED and hospital use. There are now several reports suggesting that the rates of asthma hospitalizations and ED visits have decreased during COVID-19. [4] [5] [6] In this letter, we present trends of ED and hospital use for asthma exacerbations in a sample of people from across the US. We used the Optum Labs Data Warehouse (OLDW), a database of healthcare claims for over 200 million privately insured and Medicare Advantage enrollees, to build the cohort, starting with all enrollees who had a diagnosis of asthma using diagnostic codes from 2007-2020. 7 We defined ED and hospitalization events due to asthma as those where asthma was in the first diagnostic position for the claim or Our findings suggest that the decline in asthma exacerbations during the COVID19 pandemic are not unique to specific hospital systems or geographic locations. A study in Philadelphia, PA, found an 84% decrease in the emergency and inpatient settings, a study in Orange County, CA, found a 78% decrease in hospitalization and 90% decrease in emergency visits, and a prospective study in multiple US locations found a 41% reduction in asthma exacerbations using composite, patient-informed definition. 8, 9, 10 The significant decline in asthma exacerbations during the COVID-19 pandemic suggests, but does not prove, a causal relationship between physical distancing practices and reduced asthma exacerbations. Our results do not exclude the possibility that patients and families chose to avoid ED and hospital care for asthma during COVID. However, Salciccioli et al describe a similar trend in a prospective study that captured both remote and in-person asthma exacerbations, making it less likely for the result to be influenced by healthcare system avoidance. 10 Also, when they controlled for medication use and for air quality values, the decrease in asthma exacerbation rates were still observed. 10 Similarly, another study found that increased asthma medication adherence during the COVID-19 pandemic was not observed, at least in that population. 8 While we cannot exclude the possible influence of healthcare avoidance, air quality, or medication-taking behavior, these other studies suggest these factors are unlikely to be primary drivers of the decrease in asthma exacerbations rates. Our data, showing this trend in a large sample in the US, are consistent with previous studies demonstrating this trend, and further extend previous observations by comparing rates to 13 prior years and by using participants who were not enrolled in research studies. Our findings, together with other related studies, call for further research to better understand which NPIs may be most effective at reducing asthma exacerbations. Prospective trials of different NPI approaches (e.g., wearing facemasks during fall-winter respiratory infection season) could isolate interventional effects and potentially provide new management options for our patients with asthma. Decrease in hospital admissions for respiratory diseases during the COVID-19 pandemic: a nationwide claims study Decreased influenza activity during the COVID-19 pandemic-United States Public health measures during COVID-19 pandemic reduced hospital admissions for community respiratory viral infections Initial effects of the COVID-19 pandemic on pediatric asthma emergency department utilization COVID-19 lockdown dropped the rate of paediatric asthma admissions Impact of the COVID-19 Pandemic on Pediatric Emergency Department Use for Asthma Optum Labs: Building A Novel Node In The Learning Health Care System Pediatric Asthma Health Care Utilization, Viral Testing, and Air Pollution Changes During the COVID-19 Pandemic Evaluating the impact of coronavirus disease 2019 on asthma morbidity: A comprehensive analysis of potential influencing factors Effect of COVID19 on asthma exacerbation