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Serum Anion Gap Predicts All-Cause Mortality in Patients with Advanced Chronic Kidney Disease: A Retrospective
Sung Woo Lee1, Sejoong Kim2, Ki Young Na2,3
1Department of Internal Medicine, Eulji General Hospital, Seoul, 01830, Korea.
Insights
Albumin-adjusted serum anion gap (A-SAG) is a significant predictor of mortality in advanced chronic kidney disease (CKD) patients. Higher A-SAG levels indicate an increased risk of death in this vulnerable population.
Area of Science:
- Nephrology
- Clinical Chemistry
Background:
- Advanced chronic kidney disease (CKD) is associated with high cardiovascular outcomes and mortality rates.
- Identifying novel risk factors is crucial for improving clinical outcomes in CKD patients.
Purpose of the Study:
- To investigate the albumin-adjusted serum anion gap (A-SAG) as a potential independent risk factor for all-cause mortality in advanced CKD patients.
Main Methods:
- Retrospective analysis of data from 440 CKD patients (eGFR 15-60 mL/min/1.73m2).
- Calculation of A-SAG and analysis of all-cause mortality over a median follow-up of 5.1 years.
- Statistical analysis including ROC curve and Cox proportional hazards models after adjusting for confounders.
Main Results:
- A-SAG above 9.48 mmol/L was independently associated with a nearly threefold increased risk of all-cause mortality (HR 2.968, P=0.025).
- The area under the ROC curve for A-SAG predicting mortality was 0.616 (P=0.037).
- Serum beta-2 microglobulin and blood urea nitrogen (BUN) levels were positively correlated with A-SAG.
Conclusions:
- A-SAG is an independent risk factor for all-cause mortality in advanced CKD.
- Elevated A-SAG may be linked to increased beta-2 microglobulin or BUN levels.
- Further research is warranted to explore the clinical implications of A-SAG in CKD management.
Background And Objectives:
Cardiovascular outcomes and mortality rates are poor in advanced chronic kidney disease (CKD) patients. Novel risk factors related to clinical outcomes should be identified.
Methods:
A retrospective analysis of data from a randomized controlled study was performed in 440 CKD patients aged > 18 years, with estimated glomerular filtration rate 15-60 mL/min/1.73m2. Clinical data were available, and the albumin-adjusted serum anion gap (A-SAG) could be calculated. The outcome analyzed was all-cause mortality.
Results:
Of 440 participants, the median (interquartile range, IQR) follow-up duration was 5.1 (3.0-5.5) years. During the follow-up duration, 29 participants died (all-cause mortality 6.6%). The area under the receiver operating characteristic curve of A-SAG for all-cause mortality was 0.616 (95% CI 0.520-0.712, P = 0.037). The best threshold of A-SAG for all-cause mortality was 9.48 mmol/L, with sensitivity 0.793 and specificity 0.431. After adjusting for confounders, A-SAG above 9.48 mmol/L was independently associated with increased risk of all-cause mortality, with hazard ratio 2.968 (95% CI 1.143-7.708, P = 0.025). In our study, serum levels of beta-2 microglobulin and blood urea nitrogen (BUN) were positively associated with A-SAG.
Conclusions:
A-SAG is an independent risk factor for all-cause mortality in advanced CKD patients. The positive correlation between A-SAG and serum beta-2 microglobulin or BUN might be a potential reason. Future study is needed.
Trial Registration:
Clinicaltrials.gov NCT 00860431.
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