ASN's Mission

To create a world without kidney diseases, the ASN Alliance for Kidney Health elevates care by educating and informing, driving breakthroughs and innovation, and advocating for policies that create transformative changes in kidney medicine throughout the world.

learn more

Contact ASN

1401 H St, NW, Ste 900, Washington, DC 20005

email@asn-online.org

202-640-4660

The Latest on Twitter

Kidney Week

Abstract: SA-PO191

Phosphate Overload Index and Risk of Cardiovascular Disease and Death in CKD: The CRIC Study

Session Information

Category: Bone and Mineral Metabolism

  • 402 Bone and Mineral Metabolism: Clinical

Authors

  • Chen, Jing, Tulane University School of Medicine, New Orleans, Louisiana, United States
  • Wolf, Myles, Duke University, Durham, North Carolina, United States
  • Isakova, Tamara, Northwestern University, Evanston, Illinois, United States
  • Geng, Siyi, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, United States
  • He, Hua, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, United States
  • Rosas, Sylvia E., Harvard University, Cambridge, Massachusetts, United States
  • Lora, Claudia M., University of Illinois Chicago, Chicago, Illinois, United States
  • Jaar, Bernard G., Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
  • Hamm, L. Lee, Tulane University School of Medicine, New Orleans, Louisiana, United States
  • Go, Alan S., Kaiser Permanente Division of Research, Oakland, California, United States
  • He, Jiang, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, United States
Background

Phosphate (Pi) overload may lead to adverse outcomes in CKD, but challenges persist in evaluating Pi overload because serum Pi levels remain in the normal range via tight regulation until later CKD stages, while FGF23 and PTH levels may be affected by factors including eGFR besides Pi. We developed a Pi overload index and studied its relationship with CVD and death in CKD.

Methods

The CRIC Study enrolled 3939 adults with CKD and without cirrhosis in the US. 3578 participants without missing data were included in this analysis. Atherosclerotic CVD (ASCVD) was defined as ischemic stroke, myocardial infarction, or peripheral artery disease. Incident ASCVD, heart failure (HF), and death events were adjudicated by the outcome assessment committee. Pi overload index was calculated as [serum Pi x (urinary Pi/Cr ratio) x alkaline phosphatase (ALP- a marker reflecting bone turnover)] to synergistically reflect the effect of high Pi intake on serum Pi, kidneys, and bones. Cox proportional hazards models were used to examine the multivariable association of baseline Pi overload index with the outcomes.

Results

During up to 13-year median follow-up, 769 ASCVD, 862 HF, and 1502 death events occurred. ALP was significantly correlated with serum Pi and PTH and began trending up at CKD stage 2. Pi overload index was significantly and positively correlated with 24-hour urinary Pi, FGF23, PTH, and dietary Pi and also began trending up at CKD stage 2. Higher Pi overload index was associated with higher rates of CVD outcomes and death in mulItivariable models(Table).

Conclusion

Pi overload index was independently associated with CVD outcomes and death and began trending up at CKD stage 2. Its value in diagnosing Pi overload needs to be confirmed in future studies.

Multivariable-Adjusted Hazard Ratios of Clinical Outcomes Associated with Phosphate Overload Index
QuartileASCVD
HR (95% CI)
HF
HR (95% CI)
Death
HR (95% CI)
Phosphate Overload Index   
< 121ReferenceReferenceReference
121 to < 1751.13 (0.91, 1.40)1.04 (0.84, 1.29)1.03 (0.88, 1.20)
175 to < 2591.26 (1.02, 1.56)1.10 (0.89, 1.36)0.98 (0.84, 1.15)
≥ 2591.37 (1.10, 1.71)1.26 (1.02, 1.56)1.28 (1.10, 1.50)
P value for linear trend0.0030.030.006

Adjusted for ASCVD risk factors, education, CVD, BMI, hemoglobin, 24-hour urinary protein, eGFR, and FGF23.

Funding

  • NIDDK Support