WASHINGTON—Patients on hemodialysis (HD) who have elevated serum phosphate levels may be at increased risk for peripheral artery disease (PAD), according to new study findings presented at the American Society of Nephrology’s Kidney Week 2019 meeting.
Of 3506 patient on HD in the Q-cohort study, PAD developed in 257 (7.3%) over 10 years of follow-up, Sho Shimamoto, MD, of Kyushu University in Fukuoka, Japan, and colleagues reported. PAD was identified by intervention including endovascular therapy, revascularization, and amputation.
At baseline, investigators grouped patients into quartiles by their serum phosphate level: Q1 (886 patients), levels less than 4.2 mg/dL; Q2 (838 patients), levels 4.2 to 4.8 mg/dL; Q3 (90 patients), levels 4.9 to 5.6 mg/dL; and Q4 (873 patients), levels of 5.7 mg/dL or more. In an adjusted, multivariate Cox proportional hazards risk model, PAD risk increased significantly by 23% for every 1 mg/dL increase in serum phosphate concentration. Furthermore, Q4 patients had a significant 72% higher risk for PAD compared with Q1 patients. Patients with a history of cardiovascular events (but no diabetes) and those with high serum C-reactive protein levels appeared particularly prone to PAD.
Although serum phosphate is a known risk factor for cardiovascular events in hemodialysis patients, the new study findings clarify the relationship between serum phosphate level and PAD risk.
“Peripheral artery disease (PAD) is caused by arteriosclerosis and is one of the critical cardiovascular complications in hemodialysis patients,” Dr Shimamoto’s team noted.
According to 2005 guidelines from the Kidney Disease Outcomes Quality Initiative (KDOQI), patients should be evaluated for the presence of peripheral vascular disease at dialysis initiation. Evaluation should include physical examination including an assessment of arterial pulse and skin integrity. Specialized studies, such as duplex studies or invasive testing, should be undertaken if abnormalities are detected.
Despite the increased use of endovascular procedures over open procedures to treat PAD, controversies persist on the optimal treatment for patients with end-stage renal disease and critical limb-threatening ischemia, a Kidney Disease Improving Global Outcomes (KDIGO) work group stated. KDIGO is hosting a controversies conference on central and peripheral arterial diseases in CKD in Ireland in February 2020. The group noted that risk models such as Society of Vascular Surgery’s Wound, Ischemia and Foot Infection (WIFI) and others may allow a more individualized approach to inform clinician and patient decision-making.
Shimamoto S, Yamada S, Hiyamuta H, et al. Association of serum phosphate with peripheral artery disease (PAD) in hemodialysis patients: Ten-year outcomes of the Q-Cohort Study. Presented at the American Society of Nephrology’s Kidney Week 2019 meeting held November 5 to 10, 2019, in Washington DC. Abstract FR-PO168.
National Kidney Foundation K/DOQI Clinical Practice Guidelines for Cardiovascular Disease in Dialysis Patients. Am J Kidney Dis 45:S1-S154, 2005 (suppl 3).
KDIGO Controversies Conference on Central & Peripheral Arterial Diseases in CKD. Accessed on December 10, 2019 at https://kdigo.org/wp-content/uploads/2019/06/KDIGO-Central-Peripheral-Arterial-Disease_Scope-for-Public-Review.pdf