Chronic kidney disease (CKD) is the gradual, and often permanent, loss of kidney function. It is a progressive condition that can result in significant morbidity and mortality. The condition is common in the elderly , and impacts the PACE population. Nearly 50% of individuals over 70 years old meet the definition of CKD and 38% of this age group has stage 3 or stage 4 CKD.
Two of the most notable causes of CKD are hypertension (HTN) and diabetes mellitus (DM.) Patients with HTN, DM, and family history of kidney failure are at a higher risk for developing CKD and should be monitored closely.
Kidney damage can be defined as structural or functional abnormalities of the kidney, evidenced by markers, such as microalbuminuria, polycystic kidneys, hydronephrosis, kidney size, cortical thickness, etc. Microalbuminuria is a definable marker of kidney damage and can be measured with a spot urine check. Levels of >30 mg/dl (MA/Cr ratio) are significant for clinical microalbuminuria. This is a simple test that can be performed in the clinic.
Observation, control of blood pressure.
Observation, control of blood pressure and risk factors.
Planning for endstage renal failure.
To define kidney disease as chronic, the kidney abnormalities must be chronic, as evidenced by repeated findings over time. For example, to establish CKD 3, two eGFR values <60, must have occurred at least 90 days apart. An eGFR < 60 represents a loss of at least half of the normal function of the kidneys, and is presumed to represent kidney damage. Therefore, all individuals with an eGFR <60 mL/min/1.73 m2 for 3 months are considered CKD with or without kidney damage.
As noted in the above chart, for CKD stages 1 and 2, there must be other evidence of renal disease to properly diagnose, thus supporting the need to first identify if kidney damage exists.
The eGFR can fluctuate in patients and this is common. It is not uncommon for these fluctuations to be large and require movement of stages, either up or down. The main concern is whether the eGFR is progressively worsening.
Many methods have been used to calculate eGFR, and others are still being proposed. Most commercial and hospital laboratories use the MDRD (Modified Diet in Renal Disease) equation, as this formula requires only age, gender, and other factors readily available to the lab. The chief problem for PACE participants is that the MDRD method has not been validated in patients over 70 years old and thus risks under-detecting CKD in the aged.
Another method of measuring kidney function is the Cockcroft-Gault equation. This method is based on age, ideal weight and creatinine. It's widely employed by pharmacists as the equation for creatinine clearance is used to determine renal dosing of many medications. As such, this method has direct clinical relevance for PACE participants, whose multi-morbid conditions mean they take an average of nine or more medications.
Either of these methods are easily available to the practitioner on smartphone apps. Capstone recommends the Cockcroft-Gault method, especially for those over 70 years old.
The key to proper diagnosis and coding of CKD is to first, establish presence of kidney damage, assess the eGFR, and document, document, document.