Clinical Characteristics and Outcomes of Hyperphosphatemia in Patients with Chronic Kidney Disease Stages 1–2

Abstract

Introduction: There was limited research on the epidemiology of hyperphosphatemia in early-stage chronic kidney disease (CKD) patients. We aimed to explore the clinical characteristics and prognostic value of hyperphosphatemia in patients with CKD stages 1–2. Methods: We enrolled adult patients with CKD stages 1–2 from 24 regional central hospitals across China. Hyperphosphatemia was defined as a serum phosphate level exceeding 1.45 mmol/L. The study outcomes included all-cause and cardiovascular (CV) mortality. Cox proportional hazard models were used to investigate the association of hyperphosphatemia with all-cause and CV mortality. Results: Among 99,266 patients with CKD stages 1–2 across China, the prevalence of hyperphosphatemia was 8.3%. The prevalence of hyperphosphatemia was increased with the level of urinary protein and was higher in younger and female patients. Among 63,121 patients with survival information, during a median of 5.2 years follow-up period, there were 436 (8.0%) and 4,695 (8.1%) deaths in those with and without hyperphosphatemia, respectively. After adjusting for potential confounders, compared with patients without hyperphosphatemia, patients with hyperphosphatemia were associated with a higher risk of all-cause mortality (hazard ratio: 1.28, 95% CI: 1.16–1.41). Although nearly 60.3% of hyperphosphatemia could be relieved without phosphate-lowering drug therapy among patients with CKD stages 1–2, transient hyperphosphatemia was also associated with an increased risk of all-cause mortality (p = 0.048). Conclusions: Hyperphosphatemia was not rare in patients with CKD stages 1–2 and was associated with an increased risk of mortality. Clinicians should closely monitor serum phosphorus levels in patients with CKD, even in those with normal kidney function.

Keywords

• chronic kidney disease
• early-stage chronic kidney disease
• hyperphosphatemia
• mortality