Using Real-World Evidence to Understand Disparities, Clinical Inertia

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Merck's Center for Observational and Real-World Evidence has spent several years gathering evidence on clinical inertia and is now working on solutions to overcome it at the point of care.

Treatments for diabetes have never been better. In particular, the number of therapy choices for those with type 2 diabetes (T2D) has multiplied to 40 branded medications across 12 different classes over the past 20 years.

That’s the good news. The bad news, according to a report issued last winter by the American Diabetes Association (ADA), is that the average glycated hemoglobin (A1C) in the United States hasn’t budged in a decade.1

There are many reasons for this, but one that ADA has identified is clinical inertia, which occurs when patients’ therapy is not increased even though they are not reaching their glycemic targets. The phenomenon prompted ADA to convene a clinical inertia summit last November with researchers, clinicians, leaders from industry, and other stakeholders to review evidence and make recommendations on this problem. The initiative, “Overcoming Therapeutic Inertia: Diabetes For Life,” is ongoing.

Clinical inertia isn’t just a concern of the ADA. It’s also one of the issues that interests researchers at Merck’s Center for Observational and Real-World Evidence (CORE), which uses claims data and other databases for observational studies, which are used to demonstrate the value of therapies and to understand challenges such as medication adherence.

One of CORE’s leaders, Swapnil Rajpathak, MBBS, DrPH, executive director for the center’s cardiometabolic section, took part in ADA’s summit on clinical inertia last fall and shared observations in a white paper based on CORE’s research with Cleveland Clinic, Harvard, Carolinas Healthcare System, and Aetna. “Findings from US studies showed that a large proportion of patients with type 2 diabetes were not meeting their glycemic targets on metformin, had no or delayed treatment intensification, and among those whose medication regimen was intensified, had a median time to intensification of more than 1 year,” he said.

By contrast, Rajpathak shared that a study conducted with Aetna showed that following clinical guidelines helps improve outcomes—and lower costs—in high-risk subgroups.

Yet, in the real world, things may or may not turn out this way. The American Journal of Managed Care® spoke with Rajpathak during ADA’s 79th Scientific Sessions in San Francisco, California, held June 7-11, 2019, about studies that CORE was presenting at the meeting regarding disparities and clinical inertia.

Race, Age Can Affect Clinical Inertia


Rajpathak said that for years, most of the research into disparities in diabetes has involved disease burden. Merck has spent the past 3 to 4 years gathering evidence about disparities in disease management, including data about how race and age can affect clinical inertia.

“We know there is disparity in the levels of control. We are hypothesizing that clinical inertia may contribute to that disparity,” said Rajpathak.

The first abstract presented at ADA used 2015 data from the GE Centricity Electronic Medical Record Data Base.2 Researchers identified patients with T2D taking metformin and at least 1 other antihyperglycemic agent and who had been enrolled in the database at least 12 months prior to starting dual therapy. Participants had their therapy intensified at some point during the 2 years after the start of the study.

They found that older patients were less likely to have their therapy intensified at higher A1C levels than younger patients. In recent years, guidelines have allowed for more flexibility in glycemic control with older patients to avoid hypoglycemia, but it’s impossible to say whether this is the reason for this finding.

Compared with white patients, black patients were more likely to have their therapy intensified at higher A1C levels. There was no apparent pattern of intensification by geographic region.

Rajpathak was asked: does this mean physicians are waiting until black patients have higher A1C levels to give them an additional drug for T2D? He said that can’t be inferred from the data.

Type of Coverage Affects Glycemic Control

“We don’t have a good metric to measure the underserved population,” Rajpathak said. “A proxy we use is a patient who has no insurance or patients who have Medicaid, who typically are low-income.”

This proxy came up in a second study, which linked results from the National Health and Wellness Survey, a self-administered internet survey of about 75,000 adults 18 years or older, with 2 electronic health record (EHR) databases that totaled more than 100 million patients. The study population included adults with T2D who responded to the survey from 2015-2018 and EHR database measurements for at least 6 corresponding months.

Patients were recorded as having an A1C of either less than 7% or 7% or greater. Of the 501 patients recorded, black patients were significantly more likely to have uncontrolled A1C than white patients (odds ratio [OR], 2.0; 95% CI, 1.02-3.92; P = .04) , and Medicaid and uninsured patients were far more likely to have uncontrolled A1C than those with commercial insurance (OR, 2.81; 95% CI, 1.46-5.4; P <.005). There were no differences by geographic region.3

Study of Kaiser Permanente Belies Expectations

The Merck group’s study of data of T2D patients in the Kaiser Permanente system show that access to quality care can close the disparity gap. Researchers identified adult patients diagnosed with T2D between 2003 and 2014 and followed them through June 30, 2018. Demographic data, cardiovascular disease risk factors, medical history, and medication use were all recorded from the EHR. Age- and sex-adjusted rates of mortality and events—heart attacks and heart failure—were estimated by race and ethnicity. All-cause mortality and incidence of heart attacks and heart failure were slightly higher among white patients than black patients in the Kaiser system, although the differences were not large.4

Looking Ahead to Solutions

Rajpathak said that the research that Merck’s CORE group has undertaken will now be used to test solutions, including projects with the Cleveland Clinic.

“Clinical inertia doesn’t always equal physician inertia,” he said. “That’s a common misconception.” Lack of treatment intensification can be related to patient factors—if a physician knows that the patient isn’t taking the prescribed medication, they may try to get the patient to stick with a dosing schedule first, instead of adding a prescription the patient may not take.

Rajpathak said factors such as a physician’s lack of time can also contribute to the problem. The Merck group now wants to test different point-of-care solutions to overcoming clinical inertia, such as prompts from an EHR. Solutions will likely involve getting patients more engaged and target not just the physician, but the multidisciplinary team—diabetes educators, pharmacists, and nurses.

What about continuous glucose monitoring (CGM)? Rajpathak said that some newer systems, including Abbott’s FreeStyle Libre, are less invasive, but use of CGM for those with T2D “is still a debated issue.”

Work on disparities suggests that besides racial and age differences, insurance status can affect whether clinical inertia occurs.

“Clinical inertia awareness is important—not just in the United States—it’s a global issue,” Rajpathak said.


  1. Carls G, Huynh J, Tuttle E, Yee J, Edelman SV. Achievement of glycated hemoglobin goals in the US remains unchanged through 2014. Diabetes Ther. 2017;8:863-873.
  2. Fernandes G, Sawhney B, Hannachi H, et al. Clinical inertia in relation to sociodemographic factors among patients with type 2 diabetes (T2D) in the United States. Presented at: American Diabetes Association 79th Scientific Sessions, San Francisco, CA; June 7-11, 2019. Abstract 1496-P.
  3. Pawaskar M, Nguyen J, Huynh S, Haskell T, Lee L, Rajpathak S. Socioeconomic disparities in the management of glycemic control among adults with type 2 diabetes in the United States. Presented at: American Diabetes Association 79th Scientific Sessions, San Francisco, CA; June 7-11, 2019. Abstract 1496-PUB.
  4. An J, Nichols GA, Qian L, et al. Racial and ethnic disparities in mortality and cardiovascular disease in patients with type 2 diabetes in a US integrated healthcare system. Presented at: American Diabetes Association 79th Scientific Sessions, San Francisco, CA; June 7-11, 2019. Abstract 423-P.