Survival of hospitalized COVID-19 patients in Northern Italy: a population-based cohort study by the ITA-COVID19 Network
Authors: Rossi P. Giorgi , Ferroni E. , Alegiani S. Spila , Pitter G. , Leoni O. , Cereda D. , Marino M. , Pellizzari M. , Sultana J. , Trifirò G. , Massari M. ,   the ITA-COVID19 working group
Published: May 2020

Background

COVID-19 case fatality rate in hospitalized patients varies across countries and studies, but reliable estimates specific for age, sex, and comorbidities are needed to design trials for COVID-19 interventions. Aim of this study is to provide population-based survival curves of hospitalized COVID-19 patients.

Methods

A cohort study was conducted in Lombardy, Veneto, and Reggio Emilia using COVID-19 registries linked to hospital discharge databases containing patient clinical histories. All patients with positive SARS-CoV-2 RT-PCR test on oral/nasopharyngeal swabs hospitalized from 21st February to 21st April 2020 were identified. Kaplan Meier survival estimates were calculated at 14 and 30 days for death in any setting, stratifying by age, sex and Charlson Index.

Findings

Overall, 42,926 hospitalized COVID-19 patients were identified. Patients’ median age was 69 years (IQR: 57-79), 62·6% were males, 69·4% had a Charlson Index of 0. In total, 11,205 (26·1%) patients died over a median follow-up of 24 days (IQR: 10-35). Survival curves showed that 22·0% of patients died within 14 days and 27·6% within 30 days of hospitalization. Survival was higher in younger patients and in females. Younger patients with comorbidities had a lower survival than older ones with comorbidities.

Interpretation

Over 27% of hospitalized COVID-19 patients died within one month in three areas of Northern Italy that were heavily affected by SARS-CoV-2 infection. Such a high fatality rate suggests that trials should focus on survival and have follow-up of at least one month.

Funding

The study did not receive any external funding.

Research in context

Evidence before this study

Two recent systematic reviews with meta-analyses report case fatality rates of three to four percent in COVID-19 patients. Most studies on hospitalized cohorts report only slightly higher figures. These figures do not correspond to those derived from routinely collected clinical data in most European countries, reporting a 10% case fatality rate which has been increasing over time since the epidemic started.

Robust and precise survival estimates of hospitalized COVID-19 patients which take into account prognostic factors such as age, sex and burden of comorbidities are needed to design appropriate phase II and phase III clinical studies of drugs targeting COVID-19.

Added value of this study

In this study we present the first survival estimates by age, sex and Charlson index for a large population-based cohort of Italian hospitalized COVID-19 patients.

Implications of all the available evidence

Over 27% of COVID-19 patients died within one month from hospital admission. Such a high fatality rate suggests that studies should prioritize mortality as primary outcome. Furthermore, we found that the fatality rate reaches a plateau 30 days after hospitalization, suggesting that studies should have at least one month of follow up to observe deaths; shorter follow-up could lead to overestimation of treatment benefits.