The Impact of the COVID-19 Pandemic on Healthcare Associated Bloodstream Infections in Scottish Intensive Care Units: A Retrospective Cohort Study

BackgroundHealthcare associated blood stream infections (BSI) pose a significant risk of morbidity and mortality for patients admitted to intensive care units (ICUs). Recent evidence suggests that the COVID-19 pandemic may have impacted the risk of acquisition.AimThis retrospective cohort study explored risk factors, including patient COVID-19 admission status, associated with incidence rates of BSI in Scottish ICUs during the COVID-19 pandemic compared to a pre-pandemic period.MethodsThree national databases were linked to create a dataset of 38,081 ICU admissions across 41 ICUs during a comparator period of March 2018 to December 2019, and pandemic period of March 2020 to December 2021. Population demographics and clinical risk factors were described according to period of admission and COVID-19 admission status. Cox regression models investigated the influence of risk factors on time to BSI, using a competing risk approach to account for death as a competing event.FindingsIn non-COVID-19 patients, the first two waves of the pandemic significantly increased hazards of BSI (Wave 1 cause-specific hazard ratio (HR) 1.27, 95% Confidence Interval (CI) 1.02-1.59, wave 2a HR 1.39, 95% CI 1.14-1.70), but not mortality. COVID-19 status on admission did not significantly increase hazard of BSI in the pandemic, however there was a significant interaction between COVID-19 and the use of intubation in increasing hazard of BSI (HR 4.64, 95% CI 2.07-10.4) and COVID-19 was significant in increasing the hazard of mortality (HR 2.26, 95% CI 1.77-2.88).ConclusionWhile rates of ICU-acquired BSI were higher during the pandemic period, and in COVID-19 admissions, the reasons for this are multifactorial. Interpretation must consider the competing risk of mortality and how this is influenced by differences in patient population, along with changes that occurred during the pandemic in relation to infection prevention and control procedures, ICU pressures, and COVID-19 treatment and vaccination.