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Abstract: TH-PO018

Lower Serum Bicarbonate Is Associated with an Increased Risk of AKI

Session Information

Category: Acute Kidney Injury

  • 101 AKI: Epidemiology, Risk Factors, and Prevention

Authors

  • Shah, Neil Ramesh, University of Colorado, Denver, Colorado, United States
  • You, Zhiying, UC Denver, Aurora, Colorado, United States
  • Jovanovich, Anna Jeanette, Denver VA / University of Colorado, Denver, Colorado, United States
  • Chonchol, Michel, University of Colorado, Denver, Colorado, United States
  • Kendrick, Jessica B., University of Colorado School of Medicine, Aurora, Colorado, United States
Background

Lower serum bicarbonate levels are associated with an increased risk of kidney disease progression. Whether lower serum bicarbonate levels are associated with an increased risk of developing acute kidney injury (AKI) is unclear. We tested the hypothesis that lower serum bicarbonate levels are associated with a higher risk of developing AKI.

Methods

We included 8,393 patients from the Systolic Blood Pressure Intervention Trial (SPRINT). Serum bicarbonate levels were measured at baseline in the SPRINT study. AKI was a predetermined adjudicated adverse event that was determined by hospital admission and discharge records with AKI as a recorded diagnosis. Serum bicarbonate was examined in clinically significant cutoffs ≤ 24, 25-28 and >28 mEq/L, with 25-28 mEq/L as the reference group. Cox proportional hazard models were used to examine the association between serum bicarbonate and development of AKI.

Results

The mean (SD) age, estimated glomerular filtration rate (eGFR), and serum bicarbonate level at baseline were 68 (9) years, 77 (23) ml/min/1.73m2 and 26.3 (2.6) mEq/L, respectively. Participants with serum bicarbonate levels ≤ 24 mEq/L were more likely to be male and to have lower baseline eGFR. After a median follow-up time of 3.3 years, 293 participants developed AKI. More patients in the lower bicarbonate group developed AKI (6.1% vs 2.8% in the 25-28 mEq/L and 2.1% in the >28 mEq/L). A bicarbonate level ≤ 24 mEq/L was associated with a significantly increased risk of AKI compared to those with a bicarbonate level of 25-28 mEq/L after full adjustment (HR 1.42, 95% CI 1.1 to 1.8).

Conclusion

Lower serum bicarbonate levels are an independent risk factor for the development of AKI.

Hazard Ratio (95%CI) of AKI
Serum Bicarbonate mEq/LUnadjustedModel 1*Model 2**
≦ 24
25-28
> 28
2.11 (1.7-2.7)
1.00
1.14 (0.8-1.6)
1.42 (1.1-1.8)
1.00
0.99 (0.7-1.4)
1.42 (1.1-1.8)
1.00
1.01 (0.7-1.4)

*Model 1: adjusted for age, gender, race, treatment assignment, smoking status, history of cardiovascular disease, heart failure, baseline body mass index, blood pressure and eGFR. **Model 2: adjusted for model 1 plus class of antihypertensive medication.

Funding

  • Other NIH Support