#6283 REGIONAL VARIATION OF ACUTE KIDNEY INJURY IN COVID-19 IN ENGLAND
Authors: Kolhe Nitin , Fluck Richard , Taal Maarten 
Published: June 2023

Abstract

Background and Aims
The recent worldwide COVID-19 pandemic has identified acute kidney injury (AKI) as a serious complication of COVID-19. Previous reports suggest that AKI associated with COVID-19 has higher morbidity and mortality compared to AKI due to other causes. Limited data has suggested that regional variation in COVID-19 incidence is related to population density. However, little is known about the effect of region, SARS CoV-2 strains, steroid treatment and other determinants on incidence and mortality in patients with COVID-19 complicated by AKI. The aim of this study was to determine the regional variation of COVID-19 AKI and predictors of mortality in these patients.

Method
This retrospective cohort study used hospital episode statistics. Data were collected from all adult hospitalised patients with COVID-19 infection and AKI (diagnostic code U07.1 and N17 in any of the 20 diagnoses codes) between 1st March 2020 and 31st March 2021 until discharge. 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 in relation to publication of the RECOVERY trial. SARS CoV-2 “Other” strain was prevalent between 1st March 2020 and 21st December 2020, “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 749,844 unique admission spells in 337,029 patients with U071 code in any of the 20 diagnostic codes from 3,324,748 FCEs and admitted during the study period. We excluded patients not resident in England, multiple and duplicate FCEs within a spell. Out of 749,844 admissions, 63,147 patients had 227,268 admissions with AKI. Population incidence of AKI was highest in London at 6316 pmp and lowest in South West 2394 pmp. Mean length of stay was lowest in North East at 15.6 ± 15.9 days and highest in South West at 19.3 ± 18.3 days. London had highest proportion of patients with Asian (15.1%) and Black ethnicity (16.1%). Proportion of AKI patients dialysed varied from 2.5% in North West to 6.5% in London. Unadjusted mortality was highest in North West at 31.8% and lowest in London at 25.4%. In multivariable analysis, increasing age (OR 1.04, 95%CI 1.04, 1.04), Asian ethnicity (OR 1.13, 95%CI 1.08, 1.17), emergency admissions (OR 1.7, 95%CI 1.51, 1.9), and transfers (OR 1.18, 95%CI 1.03, 1.34), ITU admission (OR 5.16, 95%CI 4.98, 5.34) and acute dialysis (OR 2.74, 95%CI 2.6, 2.89) had higher odds of death (Figure 1a). All regions had higher adjusted odds of death as compared to London (Figure 1b). Post RECOVERY trial, the odds of death was lower with prevalent “Other” SARS CoV-2 (OR 0.78, 95%CI (0.76, 0.8) and "alfa” variant (OR 0.80, 95%CI 0.78, 0.82).

Conclusion
In this large national study of COVID AKI, London had lowest adjusted odds of death despite a higher proportion of patients receiving dialysis. The odds of death were lower after the publication of RECOVERY trial which may have resulted in practice pattern change.