Association of alkaline phosphatase with mortality in patients on peritoneal dialysis

Patients with end-stage kidney disease (ESKD) undergoing peritoneal dialysis (PD) experience high mortality rates, necessitating the establishment of reliable prognostic markers. Although serum alkaline phosphatase (ALP) is routinely measured while assessing chronic kidney disease-mineral and bone disorder, its clinical relevance for mortality risk in patients undergoing PD has not been fully established.

Using multivariable Cox proportional hazards models, this retrospective cohort study examined the association between baseline ALP levels and risk of all-cause and cardiovascular mortality in 1,108 patients with ESKD who newly initiated PD between 2000 and 2020.

The median ALP level of the overall cohort was 76.0 IU/L (interquartile range, 60.0-95.3 IU/L). The mean age of the patients was 60.6 years (standard deviation [SD], 14.4 years), and 55.8% were male. During a median follow-up of 4.0 years, a 1-SD increase in ALP level was significantly associated with a 23% and 64% higher risk of all-cause mortality (95% confidence interval [CI], 1.09-1.38) and cardiovascular mortality (95% CI, 1.21-2.24), respectively. The patients were stratified into tertiles (T1-T3) based on ALP level. Compared with the T1 group, the adjusted hazard ratios for all-cause mortality were 1.11 (95% CI, 0.84-1.48) in T2 and 1.39 (95% CI, 1.05-1.85) in T3. The relationship between elevated ALP and higher risk of all-cause mortality was consistent when ALP was treated as a time-dependent variable.

Elevated ALP levels were associated with increased risk of all-cause and cardiovascular mortality in patients undergoing PD.