Development of a COVID-19 Application Ontology for the ACT Network

Clinical data networks that leverage large volumes of data in electronic health records (EHRs) are significant resources for research on coronavirus disease 2019 (COVID-19). Data harmonization is a key challenge in seamless use of multisite EHRs for COVID-19 research. We developed a COVID-19 application ontology in the national Accrual to Clinical Trials (ACT) network that enables harmonization of data elements that that are critical to COVID-19 research. The ontology contains over 50,000 concepts in the domains of diagnosis, procedures, medications, and laboratory tests. In particular, it has computational phenotypes to characterize the course of illness and outcomes, derived terms, and harmonized value sets for SARS-CoV-2 laboratory tests. The ontology was deployed and validated on the ACT COVID-19 network that consists of nine academic health centers with data on 14.5M patients. This ontology, which is freely available to the entire research community on GitHub at https://github.com/shyamvis/ACT-COVID-Ontology, will be useful for harmonizing EHRs for COVID-19 research beyond the ACT network.

Mapping a Pandemic: SARS-CoV-2 Seropositivity in the United States

Asymptomatic SARS-CoV-2 infection and delayed implementation of diagnostics have led to poorly defined viral prevalence rates. To address this, we analyzed seropositivity in US adults who have not previously been diagnosed with COVID-19. Individuals with characteristics that reflect the US population (n = 11,382) and who had not previously been diagnosed with COVID-19 were selected by quota sampling from 241,424 volunteers (ClinicalTrials.gov NCT04334954). Enrolled participants provided medical, geographic, demographic, and socioeconomic information and 9,028 blood samples. The majority (88.7%) of samples were collected between May 10th and July 31st, 2020. Samples were analyzed via ELISA for anti-Spike and anti-RBD antibodies. Estimation of seroprevalence was performed by using a weighted analysis to reflect the US population. We detected an undiagnosed seropositivity rate of 4.6% (95% CI: 2.6 - 6.5%). There was distinct regional variability, with heightened seropositivity in locations of early outbreaks. Subgroup analysis demonstrated that the highest estimated undiagnosed seropositivity within groups was detected in younger participants (ages 18-45, 5.9%), females (5.5%), Black/African American (14.2%), Hispanic (6.1%), and Urban residents (5.3%), and lower undiagnosed seropositivity in those with chronic diseases. During the first wave of infection over the spring/summer of 2020 an estimate of 4.6% of adults had a prior undiagnosed SARS-CoV-2 infection. These data indicate that there were 4.8 (95% CI: 2.8-6.8) undiagnosed cases for every diagnosed case of COVID-19 during this same time period in the United States, and an estimated 16.8 million undiagnosed cases by mid-July 2020.

Cardiorespiratory Fitness Is Associated with Gait Changes among Firefighters after a Live Burn Training Evolution

BACKGROUND: Recommendations have been proposed for minimum aerobic fitness among firefighters but it is unclear if those criteria relate to performance on the fireground. Less fit individuals fatigue more quickly than fit individuals when working at comparable intensity and may have gait changes, increasing risk of falls. We evaluated the effect of fatigue during a live burn evolution on gait parameters and functional balance comparing them to aerobic fitness levels. METHODS: A total of 24 firefighters had gait and balance tested before and after a live burn evolution. Data were stratified by aerobic fitness of greater/less than 14 metabolic equivalents (METs). RESULTS: Analysis of gait cycles measurements before and after the live burn evolution revealed that single leg stance, cycle, and swing time decreased (p < 0.05) but there were no differences in the other measures. There were no differences in time to complete the functional balance test, or errors committed before or after a live burn evolution. When firefighters were sorted by fitness level of 14 METs, there were no differences for errors or time before or after the live burn evolution. Balance data were analyzed using a linear regression. Individuals with lower fitness levels required more time to complete the test. CONCLUSION: A 14-MET criterion failed to distinguish gait or balance characteristics in this group. However, less fit firefighters did require more time to complete the balance test (p = 0.003). Aerobic fitness alone does not predict gait changes among firefighters following a live burn evolution but does appear to influence functional balance.

Effects of Low-Dose Aspirin Therapy on Thermoregulation in Firefighters

BACKGROUND: Heart attack is the most common cause of line-of-duty death in the fire service. Daily aspirin therapy is a preventative measure used to reduce the morbidity of heart attacks but may decrease the ability to dissipate heat by reducing skin blood flow. METHODS: In this double-blind, placebo-controlled, crossover study, firefighters were randomized to receive 14 days of therapy (81-mg aspirin or placebo) before performing treadmill exercise in thermal-protective clothing in a hot room [38.8 +/- 2.1degrees C, 24.9 +/- 9.1% relative humidity (RH)]. Three weeks without therapy was provided before crossing to the other arm. Firefighters completed a baseline skin blood-flow assessment via laser Doppler flowmetry; skin was heated to 44degrees C to achieve maximal cutaneous vasodilation. Skin blood flow was measured before and after exercise in a hot room, and at 0 minutes, 10 minutes, 20 minutes, and 30 minutes of recovery under temperature conditions (25.3 +/- 1.2degrees C, 40.3 +/- 13.7% RH). Platelet clotting time was assessed before drug administration, and before and after exercise. RESULTS: Fifteen firefighters completed the study. Aspirin increased clotting time before and after exercise compared with placebo (p = 0.003). There were no differences in absolute skin blood flow between groups (p = 0.35). Following exercise, cutaneous vascular conductance (CVC) was 85 +/- 42% of maximum in the aspirin and 76 +/- 37% in the placebo groups. The percentage of maximal CVC did not differ by treatment before or after recovery. Neither maximal core body temperature nor heart rate responses to exercise differed between trials. CONCLUSION: There were no differences in skin blood flow during uncompensable heat stress following exercise after aspirin or placebo therapy.