Abstract
Case fatality rate (CFR) is used to calculate mortality burden of COVID-19 under different scenarios, thus informing risk-benefit balance of interventions both pharmaceutical and nonpharmaceutical. However, observed CFR is driven by testing: as more low-risk cases are identified, observed CFR will decline. This report quantifies test bias by modeling observed CFR as log-log-linear function of test density (tests per population) in 163 countries. CFR declined almost 20% (e.g. from 5% to 4%) for each doubling of test density (p < 0.0001); this association did not vary by continent (interaction p > 0.10) although at any given test density CFR was higher in Europe or North America than in Asia or Africa. This effect of test density on observed CFR is adequate to hide all but the largest true differences in case survivorship. Published estimates of CFR should specify test density, and comparisons should correct for it such as by applying the provided model.
Article PDF
Avoid common mistakes on your manuscript.
References
Khalil A, von Dadelszen P, Draycott T, Ugwumadu A, O’Brien P, Magee L. Change in the incidence of stillbirth and preterm delivery during the COVID-19 pandemic. JAMA 2020;324;705–6.
Taquet M, Quoidbach J, Fried EI, Goodwin GM. Mood homeosta-sis before and during the coronavirus disease 2019 (COVID-19) lockdown among students in the Netherlands. JAMA Psychiatry 2021;78;110–12.
Oran DP, Topol EJ. Prevalence of asymptomatic SARS-CoV-2 Infection: a narrative review. Ann Intern Med 2020;173;362–7.
Ioannidis JPA. Infection fatality rate of COVID-19 inferred from seroprevalence data. Bull World Health Organ 2021;99;19F–33F.
Worldometers.info. COVID-19 Coronavirus Pandemic. 2020. Available from: https://www.worldometers.info/coronavirus/.
Puntmann VO, Carerj ML, Wieters I, Fahim M, Arendt C, Hoffmann J, et al. Outcomes of cardiovascular magnetic resonance imaging in patients recently recovered from coronavirus disease 2019 (COVID-19). JAMA Cardiol 2020;5;1265–73.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
This is an open access article distributed under the CC BY-NC 4.0 license (http://creativecommons.org/licenses/by-nc/4.0/).
About this article
Cite this article
Smith, M.P. Role of Ascertainment Bias in Determining Case Fatality Rate of COVID-19. J Epidemiol Glob Health 11, 143–145 (2021). https://doi.org/10.2991/jegh.k.210401.001
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.2991/jegh.k.210401.001