When Should Patients With Kidney Disease Receive Nephrology Referral?

Maureen Salamon

September 02, 2021

Basing referral of patients with chronic kidney disease (CKD) to nephrologists on 2-year kidney failure risk exceeding 1% would catch those at higher risk without increasing referral volumes generated from current laboratory-based guidelines, new research indicates.

And combining the two methods — predicted kidney failure risk with lab values — will lead to better patient outcomes by pinpointing CKD patients who most need specialty care, said study author Vishal Duggal, MD, who was a postdoctoral fellow in medical informatics at VA Palo Alto Health Care System, Palo Alto, California while conducting the research.

"We hope this can provide guidance to primary care physicians and nephrologists to give context for their decision-making," Duggal told Medscape Medical News.

The VA is the largest provider of CKD care in the United States, developing clinical practice guidelines for CKD management that include suggested indications for nephrology referral based on laboratory values. Laboratory values that are typically used to guide referral include estimated glomerular filtration rate (eGFR) and its rate of decline per year, as well as heavy proteinuria in patients with and without diabetes. 

Duggal and colleagues — who published their findings in the American Journal of Kidney Diseases — conducted a retrospective analysis of nearly 400,000 veterans with CKD over a yearlong period to determine if referral volume would change if it was based on the estimated risk for kidney failure, rather than solely using laboratory values.

They also estimated the potential volume of nephrology referrals based on a combination of both estimated risk for kidney failure and laboratory data.

Kidney failure risk was calculated using an electronic clinical decision support tool, called Kidney Failure Risk Equation (KFRE) incorporating age, eGFR, gender, and urine albumin-to-creatinine ratio.

Targeting Fewer Patients to Specialty Care  

Among all participants with CKD not already receiving nephrology care, more than 150,000 (41.5%) had a urine albumin or protein measurement leading to computable risk for end-stage kidney disease.

More than 66,200 patients met actual laboratory indications for referral but had not previously seen a nephrologist. Among these patients, 11,752 (17.7%) were referred to nephrology in the following year, and all had a median 2-year predicted risk for kidney failure of 1.5%.

Referred patients were more likely to meet several potential referral criteria, especially eGFR <30 mL/min/1.73 m2 and heavy proteinuria. Those with heavy proteinuria with diabetes, or the eGFR indication, had the highest predicted risk for kidney failure at 2 years, at 10% and 7.1% respectively.

Boosting referral volume can be problematic if patients aren't prioritized by need, Duggal said, noting that many reasons explain why fewer than 1 in 5 CKD patients meeting lab indications for referral aren't actually referred.

This can include patient preference, he noted: "Kidney disease is a disease of aging, and some patients don't want to see a specialist or escalate their care."

"Also, not everyone who has CKD is recommended to see a nephrologist, since primary care physicians do manage a lot of CKD as well."

Basing referral on predicted kidney failure risk alone, a 2-year risk threshold of ≥1%, would identify a comparable number of patients (n = 72,948) as laboratory-based criteria, the team found, although they note that the patients identified using the KFRE tool would be at higher risk than those identified by lab values alone.

But when they combined the two — a minimum kidney failure risk of ≥1% over 2 years being applied to all new patients meeting lab-based referral indications, those pinpointed for nephrology referral dropped by 42.3%, from 66,276 to an estimated 38,229 patients.

"The current guidelines that just incorporate lab values identify a significant number of patients who are at low risk of developing end-stage kidney disease (ESKD), so incorporating kidney failure risk into current guidelines would target fewer patients to get to specialty care," Duggal explained.

KFRE Tool Can Be Found Online

Duggal emphasized that his findings do not change nephrology referral guidelines, but said physicians can find the KFRE tool online and use it to supplement their decision-making about a patient's care.

"Further incorporating this [kidney failure] risk into referral practices might highlight a patient at extremely high risk who would benefit more from an interdisciplinary care team," he said.

This could include, for example, a nutritionist to help the patient modify his or her diet. "Getting that kind of teaching process in place for a patient might be highly valuable," he added.

Duggal has disclosed no relevant financial relationships.

Am J Kidney Dis. Published online August 24, 2021. Abstract

Maureen Salamon is a freelance health and medical writer based in New Jersey.

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