U.K. Team: GFR Estimates Important

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In diabetics, this improves the accuracy of renal disease detection and mortality predictions.

SAN FRANCISCO—British researchers have endorsed U.S. guidelines stating that screening diabetic patients for renal disease should involve estimated glomerular filtration rate (eGFR) in addition to testing for albuminuria.

In the United Kingdom, screening for renal disease in diabetic patients does not usually include an eGFR measurement.

The recommendation to add eGFR was made by Richard Hoefield, MD, specialist registrar in renal medicine at Salford Royal Hospital NHS Trust, Manchester, U.K. In a study, he and his colleagues found that microalbuminuria and reduced GFR independently predict mortality in type 2 diabetics.

“The global epidemic of chronic kidney disease is a significant public health issue affecting up to 10% of the adult population in the U.K.,” Dr. Hoefield pointed out. “Diabetes remains the most common cause of end-stage renal failure in the developed world and diabetic nephropathy the leading specific primary renal diagnosis for patients starting renal replacement therapy in the U.K.”

Diabetes will affect an estimated 20 million people worldwide by 2010, with type 2 diabetes accounting for 90% of cases, he added.

The National Kidney Foundation Kidney Disease Outcomes Quality Initiative guidelines (KDOQI) and the ADA recommend testing for microalbuminuria and serum creatinine at least annually for estimation of GFR in all adult diabetics regardless of the degree of urine albumin excretion. This practice aids in early detection and prevention of progression in patients with incipient kidney disease.

Although diabetes and CKD are associated with increased cardiovascular risk and premature mortality, few population-based studies of diabetic patients have examined cardiovascular risk and mortality based on eGFR and albumin:creatinine ratio (ACR) measurements, Dr. Hoefield added.

The study population included 2,565 diabetic adults whose baseline eGFR could be calculated using the Modified Diet in Renal Disease study formula and for whom ACR values were available. Microalbuminuria was defined as a baseline ACR that exceeded 3.5 mg/mmol.

Investigators placed subjects in one of four groups: eGFR greater than 60 mL/min/1.73 m2 with

normoalbuminuria (group 1), eGFR greater than 60 with albuminuria (group 2), eGFR less than 60 with normoalbuminuria (group 3), and eGFR less than 60 with albuminuria (group 4).

Results showed that an eGFR less than 60 was the strongest predictor of MI and that an eGFR less than 60 and albuminuria had an additive effect on all-cause mortality, Dr. Hoefield reported.

All-cause mortality for patients with an eGFR less than 60 without albuminuria was similar to those with GFR greater than 60 with albuminuria (slightly more than twice that of patients with an eGFR greater than 60 with normoalbuminuria), Dr. Hoefield and his colleagues said.

The researchers reported their findings here at the American Diabetes Association annual meeting.

“These data show that especially in the U.K., where we are only screening for albumin, there is a large group of patients with increased all-cause mortality whom we are going to miss, that is, patients with a GFR less than 60 who are albuminuria-negative,” he said.

Patients whose GFR was less than 60 who had microalbuminuria had nearly five times the risk of all-cause mortality.

The rates of MI and the need for renal replacement therapy increased from groups 1 through 4, according to the investigators. The decline in renal function was 12.5 times more rapid in diabetics with albuminuria than in those without albuminuria, the researchers found. In addition, the results revealed a 2.5% yearly decline in renal function in diabetics with albuminuria compared with a 0.2% yearly decline in diabetics without albuminuria.

“Overall, our findings mean that we need to revise our recommendations on screening diabetic patients to include the eGFR, in line with U.S. recommendations,” Dr. Hoefield told Renal & Urology News. “This would allow us to identify patients at risk of multiple bad outcomes who might otherwise be missed by our current guidelines.”

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