Impact of ICU transfers on the mortality rate of patients with COVID-19: insights from comprehensive national database in France

Abstract

Background: The first wave of the COVID-19 pandemic confronted healthcare systems around the world with unprecedented organizational challenges, particularly regarding the availability of intensive care unit (ICU) beds. One strategy implemented in France to alleviate healthcare pressure during the first COVID-19 wave was inter-hospital transfers of selected ICU patients from overwhelmed areas towards less saturated ones. At the time, the impact of this transfer strategy on patient mortality was unknown. We aimed to compare in-hospital mortality rates among ICU patients with COVID-19 who were transferred to another healthcare facility and those who remained in the hospital where they were initially admitted to.

Method: A prospective observational study was performed from 1 March to 21 June 2020. Data regarding hospitalized patients with COVID-19 were collected from the Ministry of Health-affiliated national SI-VIC registry. The primary endpoint was in-hospital mortality.

Results: In total, 93,351 hospital admissions of COVID-19 patients were registered, of which 18,348 (19.6%) were ICU admissions. Transferred patients (n = 2228) had a lower mortality rate than their non-transferred counterparts (n = 15,303), and the risk decreased with increasing transfer distance (odds ratio (OR) 0.7, 95% CI: 0.6-0.9, p = 0.001 for transfers between 10 and 50 km, and OR 0.3, 95% CI: 0.2-0.4, p < 0.0001 for transfer distance > 200 km). Mortality decreased overall over the 3-month study period.

Conclusions: Our study shows that the mortality rates were lower for patients with severe COVID-19 who were transferred between ICUs across regions, or internationally, during the first pandemic wave in France. However, the global mortality rate declined overall during the study. Transferring selected patients with COVID-19 from overwhelmed regions to areas with greater capacity may have improved patient access to ICU care, without compounding the short-term mortality risk of transferred patients.

Fig. 1

Flowchart of patients with COVID-19 from the SI-VIC national registry in France from 1 March to 21 June 2020. 328 patients were lost to follow-up during their ICU stay and 265 during acute care after ICU discharge because hospital staff did not update outcome information in the SI-VIC system; 216 patients had missing information (age and sex) and eight patients were admitted to hospital prior to study commencement (1 Feb 2020)

Fig. 2

Kaplan–Meier survival curves for ICU patients with COVID-19 in France who were transferred versus those who were not transferred from 1 March to 21 June 2020

Fig. 3

Kaplan–Meier survival curves for COVID-19 patients in the ICU in France who were transferred versus those who were not transferred from 1 March to 21 June 2020 among patients hospitalized for 5 days or longer