Peritoneal dialysis patients with longer serum phosphorus time in range tied to lower mortality risk: Study

The findings, published in BMC Nephrology, highlight the importance of maintaining serum phosphorus levels within 1.13–1.78 mmol/L for peritoneal dialysis patients.

Mineral bone disease (MBD) is a common complication of end-stage kidney disease. Serum phosphorus is an essential element of the human body that is proven to be a central indicator in MBD and is critical for the initiation and progression of cardiovascular calcification (CVC), which is strongly related to cardiovascular (CV) events, CV mortality, and all-cause mortality. For every rise in 0.323 mmol/L (1 mg/dL) in phosphorus level, the risk of all-cause mortality and CV mortality increased by 18% and 13%, respectively.

Major studies about the phosphorus-mortality relationship have focused on the hemodialysis (HD) population, and the relationship between serum phosphorus time in range and mortality risk in peritoneal dialysis patients remains uncertain. Therefore, Guobao Wang, Guangdong Provincial Key Laboratory of Renal Failure Research, Guangzhou, China, and colleagues aimed to evaluate the association between serum phosphorus time in range and all-cause mortality in the Chinese PD population.

For this purpose, the researchers conducted a multicenter, retrospective, cohort study of 1,915 patients collected from 2008 to 2020 in four Chinese centers. Serum phosphorus time in range was estimated as the months during the first year a patient's serum phosphorus level was within the target range (defined as 1.13–1.78 mmol/L).

The study's primary outcome was all-cause mortality. The secondary outcomes included CV mortality and PD withdrawal. The association was assessed using the Cox proportional hazards regression model with comprehensive adjustments.

The study revealed the following findings:

· The primary outcome occurred in 13.0% of PD patients over a median follow-up of 28 months.

· The serum phosphorus time in range was negatively associated with all-cause mortality (per 3-month increments, adjusted HR [aHR], 0.83), PD withdrawal (per 3-month increments, aHR, 0.89), and CV mortality (per 3-month increments, aHR, 0.87).

· Competing-risk model showed that the relationship of serum phosphorus time in range with all-cause mortality remained stable.

· None of the variables including demographics, history of diabetes and CV disease, and several PD-related and clinical indicators modified this association.

In conclusion, the researchers observed that longer serum phosphorus time in range in the first year was significantly associated with lower all-cause mortality and CV mortality risk in PD patients. The findings stress the importance of maintaining serum phosphorus concentration within 1.13–1.78 mmol/L for PD patients.

"If confirmed, these findings suggest a potential avenue to improve clinical outcomes in this population," the researchers wrote.

Reference:

Huo, Z., Liu, D., Ye, P. et al. Longer serum phosphorus time in range associated with lower mortality risk among peritoneal dialysis patients: a multicenter retrospective cohort study. BMC Nephrol 25, 117 (2024). https://doi.org/10.1186/s12882-023-03395-9