Hospital load and increased COVID-19 related mortality in Israel

Hagai Rossman,Jonathan Somer,Eran Segal,Asaf Ben Arie,Malka Gorfine,Tomer Meir,Smadar Shilo,Uri Shalit,Rom Gutman

doi:10.1038/s41467-021-22214-z

Abstract

The spread of Coronavirus disease 19 (COVID-19) has led to many healthcare systems being overwhelmed by the rapid emergence of new cases. Here, we study the ramifications of hospital load due to COVID-19 morbidity on in-hospital mortality of patients with COVID-19 by analyzing records of all 22,636 COVID-19 patients hospitalized in Israel from mid-July 2020 to mid-January 2021. We show that even under moderately heavy patient load (>500 countrywide hospitalized severely-ill patients; the Israeli Ministry of Health defined 800 severely-ill patients as the maximum capacity allowing adequate treatment), in-hospital mortality rate of patients with COVID-19 significantly increased compared to periods of lower patient load (250–500 severely-ill patients): 14-day mortality rates were 22.1% (Standard Error 3.1%) higher (mid-September to mid-October) and 27.2% (Standard Error 3.3%) higher (mid-December to mid-January). We further show this higher mortality rate cannot be attributed to changes in the patient population during periods of heavier load.

Highlights

We assessed excess mortality using a model developed for predicting patient mortality based on data of day-by-day patient disease course[6]
We show that during a peak of hospitalizations in September and October 2020, patient deaths significantly exceeded the model’s mortality predictions, while reverting to match the predictions as patient load subsided in October, and showing renewed excess mortality as hospital load has increased again since late December
We applied a prediction model on nationwide hospitalization data originating from the Israeli Ministry of Health (MOH) to predict mortality of hospitalized patients with COVID-19 based on their age, sex, and clinical state on their first day of hospitalization

Summary

Introduction

We assessed excess mortality using a model developed for predicting patient mortality based on data of day-by-day patient disease course[6]. We show that during a peak of hospitalizations in September and October 2020, patient deaths significantly exceeded the model’s mortality predictions, while reverting to match the predictions as patient load subsided in October, and showing renewed excess mortality as hospital load has increased again since late December. As Israel has a relatively small geographical area and small population, and national restrictions were placed on the entire country at the same time (such as school closures and lockdowns) – cases and hospitalizations dynamics were similar across different hospitals, and so the analysis was conducted on a national level. Hospitalization dynamics for Israel’s 15 largest hospitals, and which account for almost 75% of national COVID-19 related hospitalizations during this period, are shown in Supplementary Fig. 1

Methods

Results

Conclusion