The Effects of Pre-Existing Hyponatremia and Subsequent-Developing Acute Kidney Injury on In-Hospital Mortality: A Retrospective Cohort Study

Abstract

Background and ObjectivesBoth hyponatremia and acute kidney injury (AKI) are common and harmful in hospitalized patients. However, their combined effects on patient mortality have been little studied.MethodsWe retrospectively enrolled 19191 adult patients who were admitted for 1 year. Pre-existing hyponatremia was defined as a serum sodium level < 135 mmol/L on the first measurement of their admission. AKI was defined as a rise in serum creatinine by ≥ 26.5 μmol/L or ≥ 1.5 times of the baseline value of creatinine during the hospital stay.ResultsThe prevalence of pre-existing hyponatremia was 8.2%. During a median 6.0 days of hospital stay, the incidence rates of AKI and in-hospital patient mortality were 5.1% and 0.9%, respectively. Pre-existing hyponatremia independently predicted AKI development and in-hospital mortality (adjusted hazard ratio [HR] 1.300, P = 0.004; HR 2.481, P = 0.002, respectively). Pre-existing hyponatremia and subsequent development of AKI increased in-hospital mortality by 85 times, compared to the patients with normonatremia and no AKI. In subgroup analysis, the AKI group showed higher rates of de novo hypernatremia than the non-AKI group during the admission. De novo hypernatremia, which might be associated with over-correction of hyponatremia, increased in-hospital mortality (HR 3.297, P <0.001), and patients with AKI showed significantly higher rates of de novo hypernatremia than patients without AKI (16.2% vs. 1.4%, P < 0.001, respectively).ConclusionPre-existing hyponatremia may be associated with the development of AKI in hospitalized patients, and both hyponatremia and hospital-acquired AKI could have a detrimental effect on short term patient mortality, which might be related to the inappropriate correction of hyponatremia in AKI patients.

Could sodium imbalances predispose to postoperative venous thromboembolism? An analysis of the NSQIP database

“…We report a 7.89% rate of pre-operative hyponatremia among surgical patients. Hyponatremia has been associated with increased mortality in patients with pre-existing acute kidney injury [ 24 ], chronic kidney disease [ 25 ], heart failure [ 26 – 29 ], COPD [ 30 ], hip fractures [ 31 ], and intracerebral hemorrhage [ 32 ]; in patients undergoing cardiac transplantation [ 33 ]; and in unselected inpatients with hyponatremia [ 9 , 34 , 35 ]. The reported mortality rate ranges from 5.2 to 22% [ 8 , 21 , 22 , 34 , 36 ].…”

Impact of Electronic Acute Kidney Injury (AKI) Alerts With Automated Nephrologist Consultation on Detection and Severity of AKI: A Quality Improvement Study

“…To minimize the information-processing burden of a real-time system, our system screened AKI events every midnight, defining AKI events as Scr concentration elevation of at least 1.5-fold or 0.3 mg/dL from baseline. 17,24 When physicians opened the patient's electronic medical record (EMR) the following morning, a pop-up window (screenshot in Fig S1, available as online supplementary material) displayed with the following message: "(Mild/Moderate/Severe) acute kidney injury (stage X). Do you want to send a consultation request to nephrology division?".…”

Simple Postoperative AKI Risk (SPARK) Classification before Noncardiac Surgery: A Prediction Index Development Study with External Validation

“…Numerous risk factors for PO-AKI have been previously reported. 1, [8][9][10][11][12][13][14][15][16][17][18][19][20] Although each reported risk factor showed some valid association with the risk of PO-AKI, the integration of such information is challenging. Nevertheless, an established risk index that can guide clinicians stratify patients' risks for PO-AKI is rare, particularly one that is practical for use in daily practice.…”