Introduction and Aims: Epidemiology of acute kidney injury requiring dialysis (AKI-D) has reported variable findings in spite of studies originating from same country. One postulated reason for this has been regional variation in the epidemiology. To understand the regional variation in AKI-D, combined regional data from a national database of hospital admissions and discharge with census data from office of national statistics (ONS) over a period of fifteen years to determine the change in trend in the regional incidence and case fatality of AKI requiring dialysis in England.
Methods: In this population-based observational study, we used the national hospital episode statistic dataset to identify 54,252 AKI-D patients of all ages, in nine regions of England between 2000 and 2015. To identify AKI-D, we included procedure codes for haemodialysis or hemofiltration and excluded codes for arteriovenous fistula or arteriovenous shunt in any of the 24 procedures during the inpatient admission. To avoid misclassification of people with end stage renal disease (ESRD) starting dialysis as AKI, we specifically excluded ESRD patients and chronic kidney disease stage 5 (CKD-5) patients starting dialysis. We excluded all AKI-D patients if they did not belong to the nine regions of England. To obtain population incidence of AKI-D for each region, we obtained mid-year population of the region in each year from 2000 to 2015 from the ONS.
Results: Of 203,758,879 completed discharges in England between 1st April 2000 and 31st March 2015, we identified 54,252 patients who had AKI-D in the nine regions of England. When AKI-D was expressed per 100,000 hospitalizations, Yorkshire had one of the lowest incidences of AKI-D throughout the 15-year period, though it had the highest increase in incidence of AKI-D (16.5 fold). From 2008 to 2015, London continued to have highest incidence of AKI-D per 100,000 hospitalizations, with the highest incidence of AKI-D in 2012-13 at 70 cases per 100,000 completed hospital discharges. In the period 2000-01, the population incidence of dialysis requiring AKI was lowest in Yorkshire at 7.9 per million people (pmp) and highest in West Midland at 25.6 pmp. However, after 15 years, in 2014-15, the population incidence was highest in London (157.8 pmp) and lowest in South West (119.5 pmp). In a multivariable adjusted model, using London as the reference, in the period of 2000-2005, North East (OR 1.38; 95%CI 1.01, 1.90), East Midlands (OR 1.38; 95%CI 1.01, 1.90) and West Midlands (OR 1.38; 95%CI 1.01, 1.90) had higher odds for death, while East of England had significantly lower odds for death (OR 0.66; 95% CI 0.49, 0.90). North East had higher odds for death in all three 5-year periods as compared to other 8 regions. In 2005-10 and 2010-15, West Midlands, East of England, South East and South West had lower odds for death as compared to London (figure 1)
Conclusions: The incidence of AKI-D has increased considerably in all regions of England in last 15-years, with considerable regional variation. There has been no significant improvement in case-fatality in any of the regions over a 15-year period.
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