Background: There are few studies investigating the relationship between phosphate level variability and clinical prognosis in hemodialysis (HD) patients. This study aimed to evaluate the impact of phosphate variability on clinical outcomes in maintenance HD patients using a population-based cohort.
Methods: We analyzed data from 55,225 patients who underwent periodic HD quality assessments and claims review. Phosphate variability was assessed using the residual standard deviation (SD) from a within-subject linear regression model based on six phosphate measurements per patient. Participants were categorized into quartiles based on phosphate variability. A balanced cohort was created using generalized boosted models for relevant covariates.
Results: After weighting, the residual phosphate SDs were 0.35 ± 0.00 mg/dL (Q1), 0.57 ± 0.00 mg/dL (Q2), 0.79 ± 0.00 mg/dL (Q3), and 1.22 ± 0.00 mg/dL (Q4). The mean follow-up duration across all quartiles was 50 ± 0.2 months. Multivariable Cox regression analysis revealed that patients in the Q4 group had a significantly higher hazard ratio (HR) for all-cause mortality and dementia compared with the Q1 group. Among all quartiles, Q1 showed the lowest HR for dementia. These trends were consistent with those observed in spline curve analyses. However, no significant association was found between phosphate variability and cardiovascular events.
Conclusions: High phosphate variability was associated with increased risk of all-cause mortality and dementia in maintenance HD patients.
Keywords: dementia; hemodialysis; phosphate; survival.