Why are death rates from COVID-19 dropping?

A new study published in the Journal of Hospital Medicine provides insight into COVID-19 death rates over time. 

Since the start of the COVID-19 pandemic, the number of infected individuals has been growing followed by increases in mortality. Initially, New York was one of the hardest hit cities and medical personnel prepared for the continuation of rising death tolls. However, recent reports show a decline in mortality trends. To understand the causes of why death rates from COVID-19 appear to be dropping, researchers at the NYU Grossman School of Medicine examined hospital mortality or discharge between the months of March and August 2020.

Information was gathered from 5,263 patient records treated at NYU Langone hospitals. All hospital cases included those who were 18 or older and who had confirmed positive for the coronavirus infection. The researchers created a death prediction model by assigning different risk factors such as age, sex, ethnicity, and disease indicators, and the severity of patient illness upon hospitalization.

The researchers find declines in average COVID-19 patient age and in death rates.

The researchers found the average hospital stay time for most patients to be around eight days. In August, the probability of death after a COVID-19 infection was 22% lower than in March. The average chronic disease diagnosis— lung disease, diabetes, etc., similarly dropped from 81-72%. Death rates were lower across all age groups, though interestingly the median patient age decreased from 63 to 47.

The decline in COVID-19 mortality cases can be attributed to a shift in population demographics from previously older to now younger individuals. Younger patients with the viral infection present with less severe symptoms, shorter course of illness, and quicker recovery. However, age is only a partial contributing factor to better COVID-19 survival. Improved illness outcomes could also be a result of social distancing, mask wearing, early testing, improved treatments, and overall greater awareness.

This study used impressive data analysing techniques to provide a big-picture overview of COVID-19 death trends, however the sample population only included those from the New York region. This limitation ignores other health systems and population demographics. Future studies are now required to expand the investigation to include more areas and people. Determining why death rates from COVID-19 are dropping provides insight into working treatments and hope to beat the virus.

Written by Melody Sayrany

References:

1. Horwitz, L. et al. Trends in Covid-19 risk-adjusted mortality rates in a single health system. (2020). doi:10.1101/2020.08.11.20172775

• Nyulangone. Study helps explain declines in death rates from COVID-19. EurekAlert! Available at: https://www.eurekalert.org/pub_releases/2020-10/nlh-she102120.php. (Accessed: 31st October 2020)

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