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How Many SARS-CoV-2-Infected People Require Hospitalization? Using Random Sample Testing to Better Inform
Nir Menachemi1, Brian E Dixon, Kara K Wools-Kaloustian
1Department of Health Policy and Management (Dr Menachemi) and Department of Epidemiology (Dr Dixon), Indiana University Richard M. Fairbanks School of Public Health and Regenstrief Institute, Inc, Indianapolis, Indiana; Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana (Dr Wools-Kaloustian); and Department of Biostatistics (Dr Yiannoutsos) and Department of Health Policy and Management (Dr Halverson), Indiana University Richard M. Fairbanks School of Public Health, Indianapolis, Indiana.
Context:
Existing hospitalization ratios for COVID-19 typically use case counts in the denominator, which problematically underestimates total infections because asymptomatic and mildly infected persons rarely get tested. As a result, surge models that rely on case counts to forecast hospital demand may be inaccurately influencing policy and decision-maker action.
Objective:
Based on SARS-CoV-2 prevalence data derived from a statewide random sample (as opposed to relying on reported case counts), we determine the infection-hospitalization ratio (IHR), defined as the percentage of infected individuals who are hospitalized, for various demographic groups in Indiana. Furthermore, for comparison, we show the extent to which case-based hospitalization ratios, compared with the IHR, overestimate the probability of hospitalization by demographic group.
Design:
Secondary analysis of statewide prevalence data from Indiana, COVID-19 hospitalization data extracted from a statewide health information exchange, and all reported COVID-19 cases to the state health department.
Setting:
State of Indiana as of April 30, 2020.
Main Outcome Measures:
Demographic-stratified IHRs and case-hospitalization ratios.
Results:
The overall IHR was 2.1% and varied more by age than by race or sex. Infection-hospitalization ratio estimates ranged from 0.4% for those younger than 40 years to 9.2% for those older than 60 years. Hospitalization rates based on case counts overestimated the IHR by a factor of 10, but this overestimation differed by demographic groups, especially age.
Conclusions:
In this first study of the IHR based on population prevalence, our results can improve forecasting models of hospital demand-especially in preparation for the upcoming winter period when an increase in SARS CoV-2 infections is expected.
