Intensity of Serum Phosphate Lowering in Patients With Nondialysis Dependent Chronic Kidney Disease and...

The association between the reduction in serum phosphate and risk of renal replacement therapy (RRT) in patients with nondialysis dependent chronic kidney disease (NDD-CKD) remains inconsistent.

Using a retrospective cohort design, we enrolled 56,440 NDD-CKD patients with hyperphosphatemia from the Optum Clinformatics Data Mart database. The study exposure was defined as the percentage change in serum phosphate. The outcome was the initiation of RRT. Cox proportional hazard models was employed for analyses.

Among 56,440 NDD-CKD patients with HP, 10,822 (19.2%) patients initiated RRT during the follow-up period. Based on the changes in serum phosphorus, patients were classified into five groups: stable group (12,745, 22.6%), severe decrease group (24,300, 43.1%), slight decrease group (14,250, 25.2%), severe increase group (957, 1.7%), and slight increase group (4,188, 7.4%). The severe decrease (adjusted hazard ratio [aHR], 0.83; 95% confidence interval (CI), 0.78-0.90, P < .001) and slight decrease (aHR, 0.92; 95% CI, 0.86-0.98, P = .008) were associated with lower risk of RRT compared with stable group. Conversely, the severe increase group (aHR, 1.16; 95% CI, 1.01-1.34, P = .037) and slight increase group (aHR, 1.14; 95% CI, 1.05-1.23, P = .002) were associated with higher risk of RRT compared with stable group. We found a "J-shaped" relationship between decreases in serum phosphorus and RRT.

Our findings indicated that significant lowering of serum phosphorus was associated with lower risk of RRT. Maintaining low serum phosphorus may have a renoprotective effect and could delay the progression to RRT among NDD-CKD patients with HP.