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Abstract: PO1734

Apparently Paradoxical Relations of Serum Phosphate and Albumin Variability with Outcomes Are Explained by the Directional Change

Session Information

Category: Health Maintenance, Nutrition, and Metabolism

  • 1300 Health Maintenance, Nutrition, and Metabolism

Authors

  • Ye, Xiaoling, Renal Research Institute, New York, New York, United States
  • ter Meulen, Karlien J., Maastricht Universitair Medisch Centrum+, Maastricht, Limburg, Netherlands
  • Usvyat, Len A., Fresenius Medical Care North America, Waltham, Massachusetts, United States
  • Kooman, Jeroen, Maastricht Universitair Medisch Centrum+, Maastricht, Limburg, Netherlands
  • Kotanko, Peter, Renal Research Institute, New York, New York, United States
  • Maddux, Franklin W., Fresenius Medical Care North America, Waltham, Massachusetts, United States
Background

Evidence indicates that variability of serum phosphate (P) and albumin (Alb) is associated with higher risk of mortality. We aimed to study the variability of P and Alb with all-cause mortality taking into account the interaction with the averaged levels.

Methods

All adult incident HD patients (pts) treated in Fresenius Medical Care NA clinics between 2010&2018 were included. Serum P and Alb levels were averaged from month(mo) 1 to 6 after HD initiation. Variability of P and Alb were described by standard deviation(SD) and directional changes(DR). All-cause mortality was recorded between mo 7 and 18. Cox proportional hazards models with spline terms were applied to explore the association between variability of P & Alb and all-cause mortality. Additionally, tensor product smoothing splines were computed to study the effect of interactions between averaged values of parameters and their variability with outcomes.

Results

We enrolled 353,142 pts. Averaged P was 4.98 mg/dL, median SD and DR were 0.92 and 1.10. Baseline Alb was 3.61 g/dL, median SD and DR were 0.21, and 0.40. Across different levels of P, higher SD of P were associated with higher risk of mortality, especially in those pts with lower averaged P. Contrasting, in pts with low Alb, higher SD was associated with reduced mortality. Regarding Alb, an unidirectional relation between DR and outcome was observed, whereas the relation between DR with outcomes was bidirectional for P (Fig1&2).

Conclusion

The relationship between P variability and mortality was apparent at all levels of P. In well-nourished pts, higher P variability are associated with increased risk of mortality, which is related to the adverse effects of both an increase and a decline of this parameter. In pts with low Alb, the apparently paradoxical association between higher levels Alb variability and better survival due to an improvement of nutritional and inflammatory status, related to a positive DR. Due to possible nonlinear relations between risk factors and outcomes in patients on HD, variability should ideally be explored by various metrics.