P0559AKI SEASONALITY IN ENGLAND

Abstract

Abstract Background and Aims Incidence of Acute Kidney Injury (AKI) is known to be seasonal, peaking in winter months among hospitalised patients. Previous studies have suggested that the seasonality of AKI is likely to be influenced by the seasonality of the underlying acute illnesses that are associated with AKI. Mortality of patients with AKI has also been reported as being higher in winter, reflecting well-described excess winter mortality associations. Here we describe the seasonal variations of AKI alerts in England and the associated mortality rate using linked national databases. Method Serum creatinine changes compatible with KDIGO AKI stage 1, 2 and 3 are sent by laboratories in England as AKI alerts to the treating clinicians and the UK Renal Registry (UKRR). We linked the electronic AKI alerts to the Hospital Episode Statistics (HES) data, to identify patients who were hospitalised. We carried out descriptive statistics, and investigate the seasonal effect to the 30-day patient mortality from date of getting AKI alert, using multivariable Cox regression and sequentially adjusting for age, sex, Index of multiple deprivation (IMD) and peak AKI stage Results Winter has the highest number of AKI episodes (N=81,276), which is 6% higher than that in summer (N=76,329) (Table 1). For patients who had an AKI episode and admitted to hospitals, the crude 30-day mortality is higher in the winter season when compared to the summer [HR 1.28 (1.25-1.31), p<0.01] (Figure 1). After adjusting season by age, peak AKI stage, IMD and sex, winter season still has significantly higher 30-day mortality than summer [HR 1.24 (1.21-1.27), p<0.01]. Winter mortality peak is confounded by age and AKI severity, which explained the drop of hazard ratio at winter peaks; whereas season is not confounded by deprivation and sex. The pattern of seasonality varies with age, in age group 18-39, there were 26.1% of AKI episodes in summer and 23.3% in winter, whereas in age group >75, there were 23.7% in summer and 27.1% in winter. Conclusion Analysis of England data confirms seasonal peak in AKI during winter months. Additionally it shows increased risk of mortality for patients with AKI in winter months. Future work will investigate the impact of comorbidities and case-mix on outcomes. By understanding the seasonal variation of AKI, we can potentially plan preventive care and improve clinical practice.