Type 2 Diabetics in US Have Too Many HbA1c Tests

Pam Harrison

December 16, 2015

Over 60% of adults in the United States with well-controlled type 2 diabetes receive more than the recommended number of tests for HbA1c. And excessive testing increases the risk of treatment being intensified despite a patient having normal HbA1c levels, a new retrospective analysis of an administrative claims database demonstrates.

The study was published online December 8 in the BMJ, by Rozalina McCoy, MD, of Mayo Clinic, Rochester, Minnesota, and colleagues.

"I think the most important drivers of HbA1c overtesting in the US are multifactorial," Dr McCoy told Medscape Medical News.

She and her colleague identified some factors that seem to play a role in how frequently patients are tested, including the number of different healthcare providers each patient sees and whether their endocrinologist also treats type 1 diabetes patients, who do require more frequent monitoring. Also, there was a wide geographic variation in frequency of testing.

And in an accompanying editorial, Rodney Hayward, MD, University of Michigan, Ann Arbor, says the current study "probably greatly underestimates" the size of the overtreatment problem among US patients with type 2 diabetes. This common belief that there is "no harm in looking" continues to result in not just waste in the healthcare system but palpable patient harm, he stresses.

Fragmentation of Care May Be Part of Explanation

Dr McCoy and colleagues analyzed 31,545 patients with type 2 diabetes between 2001 and 2013, who had to have stable glycemic control on two consecutive tests with an HbA1c level of under 7% for entry into the study. No patients were on insulin.

HbA1c testing frequency was measured within 24 months after the second or index test, and excessive testing was classified as patients who received five or more HbA1c tests a year, while "frequent" testing meant they received three to four HbA1c tests a year. Current guidelines recommend patients with stable glycemic control receive HbA1c tests once or twice a year.

Despite the mean HbA1c being 6.2%, testing frequency was excessive in 6% of the cohort and frequent in 55%.

Excessive testing increased the odds that the treatment regimen would be intensified by 35% compared with patients who received only the recommended number of tests per year.

Treatment intensification, by adding glucose-lowering drugs or insulin, occurred in 13% of patients tested excessively, 9% of those tested frequently, and 7% of those who were tested according to the guidelines (P < .001).

There was a direct correlation between the number of healthcare providers the patient saw each year and the likelihood of being tested excessively or frequently — each additional provider increased the odds of being tested excessively by 14% (odds ratio, 1.14) and by 5% for being tested frequently, compared with patients who received testing as recommended.

"Thus, fragmentation of care could explain part of why patients received excessive or frequent HbA1c testing, as health providers in one health system might not be aware of what was done by another provider elsewhere," Dr McCoy speculated.

And endocrinologists who are used to taking care of type 1 diabetes patients might also be accustomed to checking patients' HbA1c every 3 months and simply could be erroneously extending this practice to patients with type 2 diabetes, she added.

There was also evidence that practice patterns varied significantly in different parts of the country, with the highest prevalence of excessive testing in the Northeast US census region (8.9%) and the lowest prevalence in the Midwest region (4.0%).

Use of bundled testing also decreased the odds of patients receiving excessive testing by 18% compared with having the glycemic test done alone.

"Patients might also like the positive feedback that repeated good numbers on HbA1c provide," Dr McCoy offered. "So it's a combination of many factors."

Excessive Testing Fell Between 2009 and 2011

Interestingly, excessive testing rates remained unchanged between 2003 and 2008 compared with rates observed in 2001 and 2002.

And while trends in treatment intensification were lower after 2009 compared with 2001 and 2002, there was no change over time in the likelihood that patients would have their treatment deintensified.

But between 2009 and 2010, rates of excessive testing fell by approximately 25% and by approximately half by 2011.

As Dr McCoy and colleagues note, the US National Quality Forum designated unnecessary laboratory tests to be one of the nine areas of wasteful or inappropriate care in 2008. This position statement might help explain improvements seen in excessive testing rates after 2009, they suggest.

"The goal of our study was to urge patients and their physicians to have an honest and open discussion about the risks and benefits of both testing and treatment of type 2 diabetes," Dr McCoy said.

"Small variations in HbA1c should be expected and should not form the basis for treatment change," she added.

"Individualization is a very important part of taking care of these patients."

Focus Resources on Subgroup of Type 2 Diabetics With Poor Control

In his editorial, Dr Hayward says that current guidelines for HbA1c targets for type 2 diabetes "have changed little from those opinions originally formed 25 years ago when end-stage diabetes complications were rampant."

However, current evidence suggests that intensive HbA1c control does not benefit patients over the age of 50 with type 2 diabetes all that much.

This is partly because current therapies and strategies, including access to metformin, home blood glucose monitoring, and many good antihypertensive agents substantially reduce end-stage complications from the disease.

"Thus, it should not be surprising that recent evidence has found intensive glycemic control to have a small absolute effect on end-stage complications for most patients with type 2 diabetes," Dr Hayward states.

"And as the benefits of tighter glycemic control become smaller, the chances that treatment harms will outweigh treatment benefits become much greater."

He added that the public good is likely best served by spending more time and resources on the subgroup of patients who continue to be at substantial risk of diabetes-related morbidity and mortality, namely those with poor glycemic control or those with disease onset before the age of 45.

Dr McCoy is funded partly by the Agency for Healthcare Research and Quality. Disclosures for the coauthors are listed in the article. Dr Hayward has no relevant financial relationships.

BMJ 2015. Published online December 8, 2015. Article, Editorial

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