#1280 Temporal trends in chronic kidney disease and mortality after acute kidney injury
Authors: Jensen Simon Kok , Christiansen Christian Fynbo , Heide-Jørgensen Uffe 
Published: May 2024

Abstract

Background and Aims
In 2015, the International Society of Nephrology formulated the “0by25” initiative, which aims to eliminate all preventable deaths due to acute kidney injury (AKI) by 2025. Numerus publications have added focus to the importance of clinical awareness and improved treatment for AKI. Ideally, this should translate to lower rates of AKI-associated adverse outcomes such as chronic kidney disease (CKD) and death.
To our knowledge, there are no studies describing temporal trends in the incidence of CKD following AKI. Moreover, only a few studies have examined the temporal trends in mortality following AKI and these studies included highly selected groups of patients not representative of general hospitalized patients and to an even lesser degree the general population. Hence, further examination of the prognosis after AKI is required to understand temporal trends in the quality of care for AKI and establish a foundation for both preventive and therapeutic measures. Therefore, we examined the temporal trends in CKD and mortality after AKI in Denmark.

Method
We identified adult individuals with AKI from 1 January 2007 to 31 December 2018 using population-based plasma creatinine (pCr) data covering both the primary care and hospital settings. AKI was defined in accordance with the Kidney Disease: Improving Global Outcomes (KDIGO) creatinine criteria. CKD after AKI was defined as ≥2 eGFR measurements from primary care or planned outpatient hospital visits &lt;60 mL/min/1.73 m2 separated by a period of ≥90 days or by a hospital diagnoses code related to chronic dialysis or kidney transplantation. Information on all-cause death was obtained from the Danish Civil Registration System. Annual crude and sex-and-age-standardized 1-year incidence rates of CKD and mortality after AKI were estimated using direct standardization.

Results
During the 2007-2018 period, 406,207 AKIs were identified in 274,269 distinct Danish residents. The mean age at the time of first AKI was 72 years (IQR, 61; 81) and 137,185 (50%) of first-time AKIs occurred in males. Twenty-eight percent of individuals had a Charlson Comorbidity Index (CCI) score of 0, while 42% had a CCI score of 1-2, and 30% a CCI score ≥3. The mean age, sex, and CCI score distributions were stable across the study period.
The age- and sex-standardized incidence rate of CKD after AKI ranged from 102 (95% CI, 99-106) per 1000 person-years in 2018 to 126 (95% CI, 119-133) per 1000 person-years in 2014. Besides a peak in 2014, the incidence of CKD after AKI showed little variation throughout the period.
The age-and sex-standardized mortality rate after AKI ranged from 317 (95% CI, 311-323) per 1000 person-years in 2018 to 392 (95% CI, 379-406) per 1000 person-years in 2007. From 2007 to 2013 there was a stable decline in the mortality rate after AKI. From 2014 to 2018 the rate showed little variation.

Conclusion
The rate of CKD after AKI was stable throughout the period, while there was a decline in mortality after AKI, especially in the years from 2007 to 2013. The decline in mortality after AKI is encouraging; however, the stable rate of CKD after AKI, despite increasing knowledge on AKI treatment and CKD prevention, warrants an evaluation of the contemporary quality of care for AKI in Denmark.