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Abstract: FR-PO157

Analysis of the Association Between Serum Phosphorus Concentration and Mortality in Patients with Decreased Renal Function: Results from NHANES 2003-2006

Session Information

Category: Bone and Mineral Metabolism

  • 402 Bone and Mineral Metabolism: Clinical

Authors

  • Mendonça, Luís Carlos, Centro Hospitalar São João, Porto, Portugal
  • Pereira, Luciano, Centro Hospitalar São João, Porto, Portugal
  • Norton, Susana Moreira, Centro Hospitalar São João, Porto, Portugal
Background

High serum phosphorus concentration is associated with increased mortality among the different stages of chronic kidney disease (CKD). However, studies are very heterogeneous and most of them lack an appropriate adjustment for relevant confounders. This concern is particularly notable in the pre-dialysis setting. We investigated the association between serum phosphorus concentration and mortality in individuals with decreased renal function using a prospective nationwide cohort of adults from the United States of America.

Methods

We analyzed non-dialysis-dependent adults with an estimated glomerular filtration rate (eGFR) inferior to 90 ml/min/1.73m2, using data from the National Health and Nutrition Examination Survey (NHANES) 2003-2006. Serum phosphorus concentration and several covariates including albuminuria, intact parathyroid hormone (PTH), 25-OH-vitamin D, C-reactive protein (CRP) and ingested phosphorus were evaluated at baseline. All-cause and cardiovascular deaths were recorded through 31 December 2011. We used the terciles of serum phosphorus concentration which were < 3.6 (T1), 3.6-4.1 (T2) and > 4.1 mg/dL (T3). Adjusted Cox proportional hazard models were fitted to estimate hazard ratios (HR) for all-cause and cardiovascular mortality.

Results

We included 3480 individuals (males 56.9%, age 61.1±18.5 years). A total of 735 deaths was recorded over a median follow-up of 80 months. Comparing with the T1, the adjusted HR for all-cause mortality was 0.84 (95% confidence interval (CI) 0.66-1.08) for T2 (p=0.178) and 1.31 (95% CI 1.1-1.6) for T3 (p=0.013). Decreasing eGFR (p<0.001) and 25-OH-vitamin D (p=0.019) and increasing PTH (p=0.038) and CRP (p=0.02) presented a significant independent association with all-cause mortality, however, none of them had a significant interaction with serum phosphorus terciles. For cardiovascular mortality, the adjusted HR was 0.94 (95% CI 0.56-1.57) for T2 (p=0.823) and 1.24 (95% CI 0.88-1.76) for T3 (p=0.201).

Conclusion

We observed a significant independent association between the highest tercile of serum phosphorus and all-cause mortality in patients with decreased eGFR. Despite a numerical trend, it was not found a significant association with cardiovascular mortality.