#5056 REGIONAL VARIATION IN COVID-19 HOSPITALISATION AND OUTCOMES IN ADULTS IN ENGLAND
Authors: Kolhe Nitin , Fluck Richard , Taal Maarten 
Published: June 2023

Abstract

Background and Aims
The possibility that population demographic characteristics, changes in viral strain and therapeutic advances in management of COVID-19 might influence clinical outcomes is of great interest given potential regional variations. The aim of our study was to describe regional variation in COVID-19 hospitalisation rates in England and factors affecting in-hospital mortality as well as acute kidney injury (AKI).

Method
In this retrospective cohort study using hospital episode statistics, we collected data from all adult hospitalised patients with COVID-19 infection (diagnostic code U07.1 in any of the 20 diagnoses codes) between 1st March 2020 and 31st March 2021, to end of discharge period. We also extracted all available secondary diagnoses and procedure codes. Patients with codes for chronic dialysis were excluded. We divided the observation period as per the dominant SARS CoV-2 variant and further, in relation to publication of the RECOVERY trial. SARS CoV-2 “Other” strain was prevalent between 1st March 2020 and 21st December 2020 and “Alfa” between 22nd December 2020 to 17th May 2021. The end date of each phase was based on more than 50% decline in each variant.

Results
We extracted 3,24,748 finished consultant episodes (FCE) for all patients with U071 code in any of the 20 diagnoses codes and admitted during the study period. After exclusion of multiple FCEs within same spell, chronic RRT and patients not residing in England, there were 749,844 unique admission spells with ICD10 code of U071 in one of the diagnoses codes in 337,029 patients. London had the highest number of COVID-19 admissions at 131,338 (18%) followed by North-west region with 122,683 admissions (16%). Population incidence of COVID-19 hospital admissions was highest in North-west at 21,167 per million population (pmp) and lowest in South-west at 9,292 admissions pmp. Patients with COVID-19 were younger (67.0 ± 17.7 years) in London as compared to patients in East of England (72.2 ± 16.8 years). Length of stay was lowest in North-east (12.2 ± 14.9 days) and highest in North-west (15.2 ± 17.9 days). As compared to London, all eight regions had higher odds of death, ranging from OR of 1.04 (95% CI 1.00, 1.07) in South-west to OR 1.24 (95% CI 1.21, 1.28) in North-west. Odds of death were lower in patients with COVID-19 in post-RECOVERY period, both with “Other” (OR 0.72, 95% CI 0.71, 0.74) and Alfa strain of SARS CoV-2 (OR 0.75, 95% CI 0.74, 0.76). Overall, AKI incidence was 30.3%. All eight regions in England had lower odds of developing AKI as compared to London. Post-RECOVERY periods with the “Other” variant (OR 0.87, 95% CI 0.85, 0.88) and “Alfa variant (OR 0.87, 95% CI 0.86, 0.88) both had lower odds of developing AKI.

Conclusion
This large national study of COVID-19 found a higher hospital admission rate and AKI incidence but lower odds of death in London compared with other regions in England. The incidence of AKI and mortality due to any cause were lower in the post-RECOVERY period irrespective of the prevalent SARS CoV-2 strain.