Chronic Kidney Disease Progression and Outcome According to Serum Phosphorus in Mild-to-Moderate Kidney Dysfunction

Abstract

SummaryBackground and objectives Several factors might alter serum phosphate homeostasis and induce hyperhosphatemia in patients with chronic kidney disease (CKD) not requiring dialysis. However, whether and to what extent hyperphosphatemia is associated with a poor prognosis in different CKD patient groups remain to be elucidated.Design, setting, participants & measurements We utilized the "Prevenzione Insufficienza Renale Progressiva" (PIRP) database, a large project sponsored by the Emilia-Romagna Health Institute. PIRP is a collaborative network of nephrologists and general practitioners located in the Emilia-Romagna region, Italy, aimed at increasing awareness of CKD complications and optimizing CKD patient care. We identified 1716 patients who underwent a GFR and serum phosphorous assessment between 2004 and 2007. We tested whether phosphate levels Ն4.3 mg/dl are associated with the risk of CKD progression or all causes of death.Results Older age and male sex were associated with lower phosphate levels. Instead, higher phosphate levels were noted in patients with diabetes. Patients with phosphate levels Ն4.3 mg/dl were at an increased risk of starting dialysis or dying (hazard ratio 2.04; 95% confidence interval [1.44, 2.90]). Notably, subgroup analyses revealed that the magnitude of the risk associated with hyperphosphatemia varied depending on age, sex, diabetes, and different stages of CKD.Conclusions These analyses lend support to the hypothesis that phosphorous abnormalities might have a negative effect on the residual renal function and prognosis in different groups of CKD patients. However, the risk associated with hyperphosphatemia might vary in specific CKD patient subgroups.

Hyperphosphatemia in Chronic Kidney Disease: Patient Characteristics and Dialysis Mortality during the First Year of Dialysis

“…The association between hyperphosphatemia and lower age is now well recognized, as it has been shown in several previous studies in different settings: in the community setting, this association was found in a general population [19], a diabetic population [20], and a CKD population [21]; in the hospital setting, the association was shown in vascular patients scheduled for major surgery [22] and also in a dialysis population [9,10]. Various mechanisms may explain this association, including increased undernutrition with age, decreased renal phosphate reabsorption, and hormonal factors.…”

Phosphorus and the Kidney: What Is Known and What Is Needed

“…These findings have been corroborated independently in other countries. For example, an Italian group showed an association between serum phosphorus and the likelihood of death in >1700 CKD patients (13). A recent meta-analysis including 47 studies and 327,644 CKD participants further supports the evidence of an association between higher serum phosphorus and mortality in this population (14).…”

Effects and safety of iron-based phosphate binders in dialysis patients: a systematic review and meta-analysis

“…Clinical evidence demonstrates that hyperphosphatemia is associated with an adverse effect on renal or cardiovascular function and an increased mortality risk, independent of other traditional risk factors. [3][4][5] The Kidney Disease Outcomes Quality Initiative (KDOQI) in the USA have recommended serum phosphorus targets of 3.5-5.5 mg/dL (1.13-1.78 mmol/L) in patients receiving dialysis. 6 Despite dietary restriction and adequate dialysis, the majority of dialysis patients suffering from hyperphosphatemia still need oral phosphate binders to control their phosphate levels and thereby reduce mortality.…”