Excess mortality and potential undercounting of COVID-19 deaths by demographic group in Ohio

Quast, T.; Andel, R.

Background: There are significant gaps in our understanding of the mortality effects of COVID-19 due to evolving diagnosis criteria, shortages of testing supplies, and challenges faced by physicians in treating patients in crisis environments. Accurate information on the number of deaths caused by COVID-19, both population wide and for demographic subgroups, is vital for policy makers and health care providers. Methods: We performed a retrospective study of weekly data for Ohio, a large American state. To estimate expected mortality in 2020 we employed data from 2010 through 2019, adjusted for secular trends and seasonality. We estimated excess mortality as the number of observed deaths less the number of expected deaths. We conducted the analysis for the entire population and by gender, race, age, and county of residence. Findings: We estimated 1,485 (95% CI 680-2,345) excess all-cause deaths in Ohio from March 15, 2020 through May 23, 2020. When limited to deaths due to natural causes, the estimated excess number of deaths increased to 2,504 (95% CI 1,633-3,221), reflecting the countervailing effect of a decrease in deaths due to external causes. While the largest number excess of deaths was observed in the 80+ age group, excess deaths comprised 45.3% (95% CI 21.8-60.9) of observed deaths in the groups corresponding to ages between 20 and 49 years old. Our estimate of 729 (95% CI 355-966) excess deaths for this group substantially exceeds the reported number of COVID-19 deaths of 51. We found elevated excess deaths for older individuals, blacks, and males. Interpretation: Our methodology addressed some of the challenges of estimating the number of deaths caused by COVID-19. Our finding of high proportional levels of excess deaths among younger age groups suggests that increases in the infection rates for this cohort may have a greater mortality impact than expected. Funding: None.