Acute Kidney Injury In Hospitalised Elderly Medical Patients: Types, Incidence, Risk Factors And Relation To Clinical Outcomes

Abstract

Background Acute kidney injury (AKI) is prevalent and increasing1,2. However, the prevalence and incidence of AKI and its relationship with chronic kidney disease (CKD) and effect on outcomes in hospitalised elderly patients are not well characterised. This study aimed to investigate the incidence, risk factors and relation to clinical outcomes of AKI, on admission and during hospitalisation, in hospitalised elderly patients.

Methods Analysis of 585 consecutive elderly (≥60 years) patients admitted to the Acute Care of the Elderly Unit (ACE) at the Canberra Hospital during 2014. Data on demographics, causes of admission, comorbidities, laboratory parameters, medications used, and clinical outcomes were collected. AKI was defined based on increased baseline serum creatinine according to Kidney Disease Improving Global Outcomes (KDIGO) criteria3. CKD was classified according to Kidney Disease Outcomes Quality Initiative (K/DOQI) criteria4.

Results AKI was diagnosed in 84 (14.4%) hospitalised patients. It was present at admission in 11.9% (53 of 445 patients in whom baseline data were available) and occurred during hospitalisation in 5.8% (31 of 530 admitted without signs of AKI) of patients. After adjustment with age and gender, the following variable were associated with AKI on admission: history of CKD stage ≥3 (OR = 51.46, 95%CI 6.99‐378.89, p < 0.001), dementia (OR = 1.90, 95%CI 1.06‐3.42, p = 0.030), atrial fibrillation (OR = 1.83, 95%CI 1.01‐3.13, p = 0.046), use of iron supplements (OR = 2.10, 95%CI 1.00‐4.38, p = 0.050), presence of leucocytosis (>11x109/L, OR = 4.48, 95%CI 2.44‐8.20, p < 0.001), metabolic acidosis (HCO3 < 22 mmol/L, OR = 2.27, 95%CI 1.25‐4.l7, p = 0.008) and hypoalbuminaemia (<33 g/L; OR = 1.98, 95%CI 1.06‐3.70, p = 0.033). Hypoalbuminaemia was also a significant determinant for developing AKI during hospitalisation (OR = 2.52, 95%CI 1.17‐5.42, p = 0.018). Stepwise regression analysis, which included age, gender, presence of CKD stage ≥3, coronary artery disease, congestive cardiac failure, dementia, chronic obstructive pulmonary disease and hypoalbuminaemia, revealed that AKI on admission or during hospitalisation was an independent and significant risk factor for in‐hospital death (OR 3.21, 95%CI 1.74‐5.92, p < 0.001), but there was no association with 3‐month readmission, or being discharged to a permanent residential care facility.

Conclusion AKI in the elderly is common, nearly one in six hospitalised geriatric patients is admitted with or developed AKI during hospitalisation. The strongest risk factors for AKI are CKD stage ≥3, dementia, atrial fibrillation and hypoalbuminaemia (a potentially modifiable risk factor). AKI on admission or during hospitalisation in elderly patients is associated with fatal outcome. These findings indicate the need of new aggressive preventive and therapeutic strategies in this population.