HbA_1c Overtesting Common in Stable, Diabetic Patients

More than 60 percent of adults with stable and controlled type 2 diabetes receive too many glycated hemoglobin (HbA_1c) tests, according to a study published online Dec. 8, 2015 in the British Medical Journal. The researchers say this excessive testing leads to potential overtreatment, waste of health care resources, and increased patient burden in diabetes management.

“Clinically unnecessary testing can have detrimental effects for both the patient and the health care system,” write the authors led by Rozalina McCoy, M.D., from the Mayo Clinic (Rochester, Minn.) “Excessive tests can cause unnecessary patient discomfort and anxiety, and because of the potential for false positive results caused by expected short-term biological and analytical variability of the HbA_1c test, they can increase the risk of further needless testing … and treatment change.”

While redundant HbA_1c testing has been previously identified as a problem, previous studies did not differentiate patients by level of glycemic monitoring needed. (Testing is recommended more frequently in those newly diagnosed, with variable glycemic control, receiving intensive insulin treatment, or undergoing treatment changes). The patients in this study had no history that would warrant intensive monitoring.

A national administrative claims database of 31,545 U.S. commercially insured adults (2001 to 2013) was retrospectively analyzed. Participants had non insulin-dependent type 2 diabetes with stable glycemic control. Testing frequency was classified as guideline recommended (2 times/ year or less); frequent (3 to 4 times/year); or excessive (5 times/year or more). Changes in treatment were evaluated through pharmacy claims within three months of the index test.

The researchers found that HbA_1c testing frequency was excessive in nearly 5.8 percent of patients and was frequent in 54.5 percent. Excessive testing increased the odds of treatment intensification, which the authors called “concerning” given that baseline HbA_1c was already less than 7 percent.

“We found that patients over age 65 years and those with high underlying disease burden were more likely to have excessive HbA_1c testing,” the researchers write. “Current guidelines recommend that patients with significant comorbidities should in fact be treated less intensely and have relaxed HbA_1c targets above 7.0 percent, making frequent testing in this population even less useful.”

There was significant geographical variability in testing frequency, with the highest prevalence of excessive testing in the Northeast (8.9 percent) and the lowest prevalence in the Midwest region (4.0 percent). Excessive testing rates remained unchanged in 2001 to 2008, but fell significantly after 2009. This may have resulted from the U.S. National Quality Forum’s designation of unnecessary laboratory tests as one of nine areas of wasteful or inappropriate care.

Takeaway: Although frequencies have dropped since 2009, excessive HbA_1c testing remains a problem in diabetic patients with stable glycemic control for whom guideline-compliant frequencies should be adequate.