Is acute kidney injury age-dependent in older adults: an observational study in two centers from North China

BACKGROUND: Although aging increases susceptibility to acute kidney injury (AKI), whether the AKI risk and the association between AKI and adverse outcomes are age-dependent remain unclear in older adults. The current study aimed to identify whether AKI risk was age-dependent in older adults and to investigate whether the association between AKI and mortality increased with increasing age. METHODS: Medical records from 47,012 adult hospital admissions, including 30,194 older adults aged 60 or older, in two tertiary general hospitals were studied retrospectively. AKI was identified based on changes in blood creatinine levels according to the Kidney Disease: Improving Global Outcomes criteria. RESULTS: Among the total population and 30,194 older adult patients, the raw incidences of AKI were 8.2 and 8.3%, respectively. The curve of the age-grouped AKI incidence was “U-shaped”, which revealed a positive relationship between the AKI incidence and age among the older adults aged 75 years or older. This trend of the age-AKI relationship was supported by further multivariable analysis. After adjusting for the Charlson Comorbidity Index score, the AKI was associated with in-hospital mortality; however, the associations did not increase with increasing age. CONCLUSION: The AKI risk does not increase with age in older adults, except for those aged 75 and above. The association between AKI and in-hospital death did not increase in an age-dependent manner in older adults. TRIAL REGISTRATION: This study was retrospectively registered at clinicaltrials.gov (NCT03054142) on February 13, 2017.