Association of serum phosphate concentration with the incidence of intervention for peripheral artery disease in patients undergoing hemodialysis: 10-year outcomes of the Q-Cohort Study

Background and aims: Peripheral artery disease (PAD) is mainly caused by atherosclerosis and is a critical cardiovascular complication in patients undergoing hemodialysis. Although hyperphosphatemia is a risk factor for cardiovascular events, whether serum phosphate concentration is associated with PAD remains unclear. This study was performed to clarify the relationship between serum phosphate concentration and the risk of intervention for PAD in patients undergoing hemodialysis. Methods: In total, 3505 patients undergoing hemodialysis registered in the Q-Cohort Study were followed up for 10 years. The primary outcome was the incidence of major adverse limb events (MALE) as a surrogate endpoint of intervention for PAD. The patients were divided into quartiles according to the baseline serum phosphate concentration: Q1 (n = 886),< 4.2 mg/dL; Q2 (n = 837), 4.2-4.8 mg/dL; Q3 (n = 909), 4.9-5.6 mg/dL; and Q4 (n = 873), >= 5.7 mg/dL. A multivariable-adjusted Cox proportional hazards risk model was employed to examine the association between the serum phosphate concentration and the risk of MALE. Results: During a median follow-up period of 8.2 years, 257 patients required intervention with MALE. The Cox proportional hazards risk model showed that the risk of MALE in Q4 was significantly higher than that in Q1 (hazard ratio, 1.81; 95% confidence interval, 1.25-2.63). Every 1-mg/dL increase in serum phosphate concentration was also significantly associated with the increased incidence of MALE (hazard ratio, 1.24; 95% confidence interval, 1.10-1.39). Conclusions: An elevated serum phosphate concentration was associated with an increased risk of MALE in patients undergoing hemodialysis.