Is it Normal Aging or Chronic Kidney Disease?

By Joseph E. Scherger, MD, MPH

Vice President, Primary Care, Eisenhower Medical Center; Clinical Professor, Keck School of Medicine, University of Southern California

Dr. Scherger reports no financial relationships relevant to this field of study.

SYNOPSIS: Current clinical guidelines for the diagnosis of chronic kidney disease (CKD) resulted in more than half of adults > 70 years of age having CKD. Should these guidelines be changed to require age calibration for diagnosis and classification of CKD?

SOURCES: Glassock R, et al. An age-calibrated classification of chronic kidney disease. JAMA 2015;314:559-560.

Levey AS, et al. Chronic kidney disease in older people. JAMA 2015;314:557-558.

Current international guidelines classify chronic kidney disease (CKD) as having an estimated glomerular filtration rate (eGFR) of < 60 mL/min.¹ As our population ages, more patients are being diagnosed with CKD, since a decline in eGFR commonly occurs with age. By current guidelines, more than 50% of seniors ≥ 70 years of age have an eGFR of < 60 and are being diagnosed with CKD, resulting in a reported “epidemic” of this condition. Two teams of three academic nephrologists provided a pair of point/counterpoint articles about whether the threshold for diagnosing CKD should be age adjusted. Speaking in favor of this change, Glassock et al point out that there has not been a commensurate increase of end-stage renal disease (ESRD) in the general population of seniors. ESRD typically occurs in high-risk patients, such as those with diabetes, hypertension, or a family history of ESRD. These authors argued that “normal aging” results in a gradual decline in kidney function and the process should not be classified as a disease. They propose lowering the threshold for classifying CKD to 45 mL/min starting at age 65.

The common decline of eGFR in the elderly is very low risk. Glassock et al noted that there are only 0.6-0.8 cases of ESRD per 1000 patient-years in adults > 65 years of age without significant proteinuria.² Proteinuria tends to occur in patients at risk for ESRD, such as diabetics and hypertensives.

The second article called for no change in the guidelines. Levey et al said that the criteria for other conditions, such as atherosclerosis or lipid disorders, do not change based on age. They noted that age-related decline in kidney function is variable and is related to circulation, so a reduction in eGFR is a marker for vascular disease. They argued that recognizing eGFR decline is an important part of the management of elderly patients, such as with adjusting medications.

COMMENTARY

I practice in the Palm Springs, CA, a popular retirement community. Most of my patients are > 65 years of age. I frequently reassure elderly patients that their mildly elevated serum creatinine (eGFR < 60 but ≥ 45) is normal in their age group, particularly for patients > 80. I strongly favor the recommendation to have an age-appropriate classification for CKD.

Giving a patient a disease label, especially kidney failure, is frightening and results in patients thinking of themselves as sick. Each time we add a disease label to patients, they consider themselves less healthy and often behave accordingly. CKD is an important area of primary care medicine and we should develop more appropriate clinical guidelines for evaluation and management of these patients. Too many patients with no life- or even health-threatening disease visit nephrologists and end up with one more specialist they may not need.

REFERENCES

1. Kidney Disease: Improving Global Outcomes (KDIGO). KDIGO 2012 clinical practice guideline for evaluation and management of chronic kidney disease. Kidney Int Suppl 2013;3:1-150.
2. Hallan SI, et al. Chronic kidney disease prognosis consortium. Age and association of kidney measures with mortality and end-stage renal disease. JAMA 2012;308:2349-2360.