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Equating eGFR Levels And Renal Function In Impaired Risk Cases

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As the aging population in the U.S. continues to expand, the life insurance industry has enhanced its focus on the risks associated with underwriting older applicants. This is particularly so when determining the level of kidney functionality among older applicants and its direct correlation to mortality rates within this demographic.

The increased attention on the elderly market has had a positive effect on underwriting decisions on older applicants. In addition, it will improve testing processes in the long term to the benefit of younger generations.

When evaluating kidney functionality, underwriters use several serum and urine test values to help assess the overall mortality risk of a proposed insured. One of the most debated of these values is the “estimated glomerular filtration rate” (eGFR). As its name suggests, it’s an estimate, not an exact measurement, and mortality assumptions can be significantly impacted by small changes to the eGFR.

The eGFR is based primarily on the concentration of serum creatinine in the blood. Serum creatinine results from the breakdown of creatine in the muscles and is excreted from the body by the kidneys.

The measure of creatinine cleared during a 24-hour period defines the creatinine clearance and correlates directly to the level of kidney function. In cases of renal disease, or where kidney damage or obstruction exists, creatinine clearance values fall. This suggests the degree of failure by the kidneys to eliminate waste and regulate the volume of body fluid.

Calculating the creatinine clearance from a blood specimen provides the underwriter with a snapshot of kidney function, but it can be “out of focus” with reality. The eGFR is the best estimate of this capability, since 24-hour urine collections are impractical, and there can be issues with accuracy in collection.

The original iteration of the eGFR calculation to determine estimated creatinine clearance used age, weight and gender to massage the serum creatinine value.

Another earlier method used race as an additional factor, based on studies available at the time that were race-based. This method often resulted in distinct differences by race when considering African Americans versus Caucasians. Since race can no longer be considered in insurance determinations and is generally transparent to the underwriter, it is not reasonable to consider for eGFR calculations.

The third and most commonly used method by many companies today disregards both race and weight. Since race cannot be used as a determinant factor in underwriting the risk and, since fat does not contribute to increased levels of creatinine in the body, the argument here is that weight should also not be a factor in evaluating proposed insureds.

Regardless of the test’s accuracy, there are other factors that can alter the result. A more favorable eGFR can result from artificially low serum creatinine levels caused by malnutrition, vegetarian diets, amputation or paraplegia, to name a few.

Additionally, unfavorable results can derive from artificially high serum creatinine caused by muscular build (or low body fat) and some medications such as cimetidine (Tagamet, which is generally available over-the-counter) or trimethoprim (Bactrim).

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There is a belief that this most commonly used method for calculating eGFR tends to create more “false positive” results because there are more factors that can lower the value rather than raise the value. However, this theory does not validate the specific results of some proposed insured clients that fall on the “false negative” side of the equation and would generally be more adversely underwritten.

Producers may wish to question an adverse decision as it relates to questionable kidney function if the producer is aware that the client has a muscular build and knows which medications the client is taking. Raising the question alone may not invalidate the mortality assumption, but it may necessitate evaluation by, and opinion from, the proposed insured’s physician in some cases where the findings could be explained by physical build or medications.

An additional factor that has been questioned is how the age of a proposed insured impacts the testing process. Laboratories disagree to some extent on this factor. Some suggest that one’s age causes no significant change in the results, but others claim that lower eGFR at older ages is a reasonable outcome. This question may need more study to be resolved, but it demonstrates the concern with the calculation.

Given the disagreements on the normal eGFR ranges expected for gender, the differences, though relatively small, demonstrate yet another element that is not entirely clear across all industry experts.

As a general rule, laboratory differences based on materials that are used to test elements of serum should not alter the rating outcome, depending on the insurance company’s use of laboratory results. But inherent in the insurance process is the existence of external factors that can artificially inflate serum creatinine results when tested in the laboratory and, therefore, any eGFR calculation.

For instance, delays in processing fluids can create artificially-high values due to glycolysis (breakdown of glucose in the serum over time) or heat exposure. The resulting high serum creatinine values create a poorer picture of renal function with the eGFR calculation. While glycolysis is evident and reported by insurance laboratories on specific specimens, the only suggested indicator for heat exposure is the time delay from collection to processing and there is no test to validate that possibility.

Even when a known delay exists in the processing or glycolysis of the serum, it should not automatically invalidate the specimen or the mortality assumptions of the case. The condition of the serum may suggest that further testing is needed by the personal physician; the goal would be to assess accurately the kidney function depending upon extent of kidney function abnormality and the specific facts on specimen handling.

Underwriting is not an exact science, and science relative to renal testing does not make underwriting any easier to navigate. The art form of underwriting, when properly used, must consider the variables and all aspects of the case before reaching the best decision on the risk to be accepted.

Sometimes, when going “by the book” is simply not the best approach, the art of underwriting can be implemented with the intention of making every rating decision as accurate as possible.

Everett Kunzelman is vice president and chief underwriter, and Clifford Hale is vice president and chief medical officer, for Jackson National Life Insurance Company, Lansing, Mich. Their respective e-mail addresses are [email protected] and [email protected]