The association of intensive care capacity transfers with survival in COVID-19 patients from a Scottish district general hospital: A retrospective cohort study

Abstract

Background: During the second wave of COVID-19 cases within Scotland, local evidence suggested that a large number of interhospital transfers occurred due to both physical capacity and staff shortages. Although there are inherent risks with transferring critically ill patients between hospitals, there are signals in the literature that mortality is not affected in COVID-19 patients when transferred between intensive care units. With a lack of evidence in the Scottish population, and as the greatest source of capacity transfers in our critical care network at that time, we sought to determine whether these transfers impacted on survival to hospital discharge. Methods: We conducted a retrospective cohort study of all patients admitted to our unit between the 1st October 2020 and the 31st March 2021 with a primary diagnosis of COVID-19 pneumonia. Patients were grouped according to whether they underwent an interhospital capacity transfer or not, either for unit shortage of beds or unit shortage of staff. The primary outcome measure was survival to ultimate hospital discharge, and secondary outcomes included total ventilator days and total intensive care unit length of stay. Baseline characteristic data were also collected for all patients. Survival data were entered into a backward stepwise logistic regression analysis that included transfer status, and coefficients transformed into odds ratios and 95% confidence intervals. Results: A total of 108 patients were included. Of these, 30 were transferred to another intensive care unit due to capacity issues at the base hospital. From the baseline characteristic data, age was significantly higher in those transferred out, while other characteristics were similar. Unadjusted mortality rates were 30.8% for those not transferred, and 40% for those transferred out. However, when entered into a logistic regression analysis to attempt to control for confounders in the baseline characteristics, being transferred had an odds ratio of 1.14 (95% confidence interval 0.43–3.1) for survival to hospital discharge. Total ventilator days and total ICU length of stay were both higher in the transferred patients. Conclusion: This unique study of COVID-19 patients transferred from a Scottish district general hospital did not show an association between transfer status and survival to hospital discharge. However, the study was likely underpowered to detect small differences. As the situation continues to evolve, a prospective regional multi-centre study may help to provide more robust findings.