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Abstract: FR-PO969

Association Between Laxative Use and Serum Phosphate Levels in Patients with CKD: A Large Nationwide Observational Study of US Veterans

Session Information

Category: CKD (Non-Dialysis)

  • 2302 CKD (Non-Dialysis): Clinical, Outcomes, and Trials

Authors

  • Sumida, Keiichi, The University of Tennessee Health Science Center, Memphis, Tennessee, United States
  • Mallisetty, Yamini, The University of Tennessee Health Science Center, Memphis, Tennessee, United States
  • Shrestha, Prabin, The University of Tennessee Health Science Center, Memphis, Tennessee, United States
  • Surbhi, Satya, The University of Tennessee Health Science Center, Memphis, Tennessee, United States
  • Thomas, Fridtjof, The University of Tennessee Health Science Center, Memphis, Tennessee, United States
  • Kalantar-Zadeh, Kamyar, University of California Irvine, Irvine, California, United States
  • Kovesdy, Csaba P., The University of Tennessee Health Science Center, Memphis, Tennessee, United States
Background

Reducing intestinal phosphate (P) absorption is key to maintain normal P balance in patients with CKD. Laxative use may enhance fecal P excretion and help reduce serum P levels; however, little is known about the association of laxative use with serum P levels.

Methods

In a nationwide cohort of 513,653 US veterans receiving care from the VA healthcare system from 2004-2006 and with ≥1 outpatient serum P measurements during the follow-up through 2019, we examined the association of time-varying non-P containing laxative use with serum P levels across CKD stages, using generalized estimating equations with adjustment for demographics, smoking status, BMI, comorbidities, and time-varying use of relevant drugs, number of different types of laxatives, serum calcium, and eGFR. Serum P levels at each P measurement were treated as a repeated multinomial outcome (i.e., <2.5 [low-P], 2.5-≤3.5 [normal-P: reference], and >3.5 mEq/L [high-P]).

Results

Patients were 66.5±11.9 years old; 94.3% were male; 20.9% were African American; and 39.4% were diabetic. Their baseline eGFR was 76.8±23.3 mL/min/1.73m2. There was no significant interaction between laxative use and eGFR (p=0.85). After multivariable adjustment, the use (vs. non-use) of laxatives was significantly associated with greater risk of low-P (adjusted OR [95% CI], 1.10 [1.04-1.16]) and high-P (1.07 [1.03-1.11]) in patients with CKD stages G1-2 (Table). The greater risk of low-P associated with laxative use was more pronounced in patients with more advanced CKD stages; while the laxative use-related risk of high-P was not evident in those with CKD stages G3-5 (Table).

Conclusion

The use of non-P containing laxatives was independently associated with greater likelihood of lower serum P levels in patients with CKD, particularly in those with more advanced CKD stages. Our findings suggest potentially distinct pharmacological contribution of laxatives to P homeostasis across CKD stages.

Funding

  • Veterans Affairs Support