Early post-transplantation hypophosphatemia and the risk of graft failure and cardiovascular mortality after kidney transplantation.

Aarts, B. (Brigit) (2015) Early post-transplantation hypophosphatemia and the risk of graft failure and cardiovascular mortality after kidney transplantation. thesis, Medicine.

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Abstract

Background and objectives Post-transplantation hypophosphatemia, phosphate levels below 0.7 mmol/L, is common after kidney transplantation. Hypophosphatemia is probably the consequence of still elevated levels of fibroblast growth factor 23 (FGF23) and parathyroid hormone (PTH). Long-term exposure to FGF23 and PTH, have been associated with adverse patient and graft outcomes, but may also reflect good graft function. We therefore investigated whether post-transplant hypophosphatemia is associated with graft failure or mortality. Design, setting, participants & measurements In a cohort of renal transplant recipients (n=957), the lowest serum phosphate during the first year post-transplantation was recorded. We analyzed the association between the lowest serum phosphate, either as a categorical (absent >0.7 mmol/L, mild 0.5-0.7 mmol/L, severe <0.5 mmol/L) or as a continuous variable (per halving), and the outcomes graft failure and mortality. This was done by multivariable Cox regression analyses adjusted for known risk factors for adverse patient and graft outcomes. Results 821 patients (86%) developed hypophosphatemia during the first year post-transplantation, of which 446 patients (47% of the total cohort) had severe hypophosphatemia. Lowest levels of serum phosphate were reached at 33 [21-51] days after transplantation. During follow-up for 9 [5-12] (median [IQR]) years, 181 (19%) patients developed graft failure and 295 (31%) patients died. The development of hypophosphatemia was significantly associated with a lower risk of graft failure (full model HR, severe vs no hypophosphatemia; 0.41 [0.22-0.73], P<0.01 mild vs no hypophosphatemia 0.41 [0.24-0.72], P<0.01). Furthermore, hypophosphatemia was associated with a reduced risk of cardiovascular mortality (severe vs no hypophosphatemia: 0.29 [95% CI 0.13-0.67], P<0.01 mild vs no hypophosphatemia: 0.25 [0.11-0.58], P<0.01). Hypophosphatemia was not associated with non-cardiovascular mortality. Conclusions The development of post-transplantation hypophosphatemia in the first year after kidney transplantation is associated with a lower risk of both graft failure and cardiovascular mortality. This indicates that an optimal renal phosphate excretion capacity after transplantation is beneficial for graft and patient outcomes.

Item Type:	Thesis (Thesis)
Supervisor name:	Navis, Prof. Dr. G.J. and Borst, Dr. M.H. de
Faculty:	Medical Sciences
Date Deposited:	25 Jun 2020 10:50
Last Modified:	25 Jun 2020 10:50
URI:	https://umcg.studenttheses.ub.rug.nl/id/eprint/1115

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