Quest Diagnostics’ tests for low density lipoprotein (LDL) cholesterol now use a new calculation that improves the tests’ accuracy and does not require the patient to fast ahead of the test. It is the first provider of nonfasting lipid testing.
The new calculation is designed to replace the standard Friedewald calculation used in cholesterol tests since 1972, Quest said in a statement. It is not affected by recent food intake and is based on a formula from Seth Martin, M.D., a cardiologist at the Johns Hopkins School of Medicine, from whom Quest has licensed the calculation.
The change in calculation does not affect pricing or insurance coverage, Quest said.
"Fasting for eight to 12 hours visiting a patient service center for a blood draw in the morning is challenging and may deter many patients from participating in lipid testing. Now, millions of people no longer have to go through this process to receive a reliable lipid test result through Quest Diagnostics," said Jay Wohlgemuth, senior vice president, R&D, medical, and chief medical officer at Quest Diagnostics, in the statement.
While patients are typically asked to fast for as many as 12 hours before taking a cholesterol blood test, new international guidelines announced last year say it’s fine—even preferable—to skip the fast. As we spend most of our days not fasting, a fasted blood cholesterol reading may not reflect our “normal” cholesterol levels, according to the rationale.
The value of the new calculation is its improved accuracy. About one-fifth of patients who had LDL cholesterol at levels below 70 mg/dL according to the old Friedewald method actually had a value of 70 mg/dL or higher, a recent study showed. This resulted in their getting the wrong treatment.
"Accordingly, ongoing use of Friedewald estimation may lead to the misclassification of high-risk individuals and subsequent under-utilization of lipid-lowering therapies," wrote the authors, which include Martin. Quest Diagnostics did not participate in the study.