CKD Stage 3 Needs To Be Redefined
Kam Kalantar-Zadeh, MD, MPH, PhD
How often have you been consulted to verify the diagnosis of “CKD Stage 3” originating from a laboratory report in which the estimated glomerular filtration rate (eGFR) was calculated using serum creatinine values in combination with age, gender, and race?
I deal with quite a few such referrals, including some healthy individuals who have no sign of kidney disease other than an eGFR reported to be slightly below the magic number of 60 mL/min/1.73m2.
Not infrequently, I have to initiate extensive and expensive work-ups consisting of several blood and urine tests, including a series of 24-hour urine collections to calculate creatinine clearance. Fortunately, in most cases, I reassure the patient that I cannot substantiate the diagnosis of CKD Stage 3 and not even Stage 1 or 2, for that matter.
I have observed devastating “you-have-CKD” scenarios involving individuals who are in a state of shock for days to weeks before they see a nephrologist. Some of these so-called “CKD patients” encounter major life and career crises, including denial of insurance coverage upon new rehiring due to being labeled as “preexisting condition.”
Some primary care doctors call patients with “bad news,” telling them, “Unfortunately, your CKD is not even the early Stages 1 or 2, but it is a Stage 3.”
The term “chronic kidney disease” and its staging was introduced in 2002 and defined as an irreversible kidney disease that lasts three months or longer. Stage 3 CKD is defined as an eGFR below 60, which usually is calculated from the Modified Diet in Renal Disease (MDRD) study equation.
Although the introduction of CKD and its staging has led to improved education and awareness about kidney disease in the general population, it is time to refine the definition and to provide a better screening level to the laboratory centers and to primary care doctors other than an eGFR below 60.
It does not make sense that, in the United States, Stage 1 and 2 CKD each includes only four million to six million individuals in the United States, Stage 4 and 5 includes around half a million individuals each, and Stage 3 alone includes more than 15 million people.
This massive overestimate of CKD Stage 3 does not serve any popular interest and may indeed damage the credibility of the nephrology community. We should rethink the screening level and offer a more conservative and meaningful cutoff level, such as an eGFR of 45.
Kamyar Kalantar-Zadeh, MD, MPH, PhD, Associate Professor of Medicine and Pediatrics, and Director, Dialysis Expansion & Epidemiology, Harbor-UCLA Division of Nephrology & Hypertension.
Dr. Kalantar-Zadeh is Medical Director, Nephrology, for Renal & Urology News.