Regional Variation of COVID-19 Admissions, Acute Kidney Injury and Mortality in England - A National Observational Study Using Administrative Data

Background: This study explores regional variations in COVID-19 hospitalization rates, in-hospital mortality, and acute kidney injury (AKI) in England. We investigate the influence of population demographic characteristics, viral strain changes, and therapeutic advances on clinical outcomes.Methods: Using hospital episode statistics, we conducted a retrospective cohort study with 749,844 admissions in 337,029 adult patients with laboratory-confirmed COVID-19 infection (March 1, 2020, to March 31, 2021). Multivariable logistic regression identified factors predicting AKI and mortality in COVID-19 hospitalized patients.Results: London had the highest COVID-19 admissions (131,338, 18%), followed by the North-west region (122,683, 16%). The North-west had the highest population incidence of COVID-19 hospital admissions (21,167 per million population, pmp), while the South-west had the lowest (9,292 admissions pmp). Patients in London were relatively younger (67.0 ± 17.7 years) than those in the East of England (72.2 ± 16.8 years). The shortest length of stay was in the North-east (12.2 ± 14.9 days), while the longest was in the North-west (15.2 ± 17.9 days). All eight regions had higher odds of death compared to London, ranging from OR 1.04 (95% CI 1.00, 1.07) in the South-west to OR 1.24 (95% CI 1.21, 1.28) in the North-west. Older age, Asian ethnicity, emergency admission, transfers from other hospitals, AKI presence, ITU admission, social deprivation, and comorbidity were associated with higher odds of death. AKI incidence was 30.3%, and all regions had lower odds of developing AKI compared to London. Increasing age, mixed and black ethnicity, emergency admission, transfers from other providers, ITU care, and different levels of comorbidity were associated with higher odds of developing AKI.Findings: London exhibited higher hospital admission rates and AKI incidence, but lower odds of death compared to other regions in England.Trial Registration: Registered on www.clinicaltrials.gov (registration number NCT04579562).Funding: None.Declaration of Interest: We declare no competing interests.Ethical Approval: The study protocol was approved by the Health Research Authority and Wales Research Ethics Committee. The research involved analysis of anonymized data collected during normal care and obtained from NHS Digital. Written informed consent was waived due to the pandemic nature of the disease. The authors analysed and interpreted the data, ensuring adherence to the protocol and the principles of the Declaration of Helsinki. The manuscript adheres to STROBE guidelines.