Adherence to the at-home, DNA-based test for colorectal cancer (CRC) detection, Cologuard, among Medicare beneficiaries was up, according to recent research — it was 71%, or higher than the overall adherence (64%) to colorectal cancer screening guidelines in the US.1 The study, published in the Journal of Medical Screening, sought to evaluate whether test-takers were using the test as directed.2

“This is definitely good news — that adherence and compliance [are] higher for this home-based method,” said Ronit Yarden, PhD, MHSA, senior director of medical affairs at the Washington, D.C.-based Colorectal Cancer Alliance, which was not involved in the research.

However, it’s unclear what impact adherence to this test will have on survival outcomes, she noted.

Cologuard is a stool-based test that combines DNA and immunochemical assays to detect early-stage CRCs. With less accuracy, it also detects advanced precancerous lesions and polyps with high-grade dysplasia. It is indicated for screening among individuals 40 years and older who are at average risk for CRC.


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According to the distributor of the assay, Exact Sciences Corporation, 95% of users see no out-of-pocket costs for the test.3 However, a recent analysis requested by the Centers for Medicare and Medicaid Services determined that at current reimbursement rates, triennial use of the test is in the long term “less effective and considerably more costly” for taxpayers than other screening tests—an assertion that Exact Sciences has pushed back against, arguing that the research was flawed.4,5

The study, which was funded by Exact Sciences, encompassed 368,000 Medicare beneficiaries (64% female) between the ages of 65 to 85 years whose physicians had prescribed a Cologuard test between September 2016 to August 2017. Adherence was defined as completion of the test within a year of the order date.

Primary care physicians (PCPs) placed the majority of orders compared with gastroenterologists (88% vs 6%, respectively), but patients getting the test through their PCPs had a lower adherence rate than those who got it from a gastroenterologist. (71% vs 78%, respectively). Overall, 71% of individuals who had a valid order for Cologuard “followed through and completed the test,” explained Paul Limburg, MD, MPH, chief medical officer for screening at Exact Sciences, professor of medicine at the Mayo Clinic, and a coauthor of the study. There was little variation in adherence across age groups, sex, Medicare coverage type, and across states. 

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Adherence rates for other tests in the CRC screening sphere vary. A retrospective longitudinal study of more than 670,800 Kaiser Permanente plan members who were invited to take an at-home fecal immunochemical (FIT) test suggested that 48.2% completed the test at the first round of screening.6 Other studies have found adherence rates of 42% or even 28% for FIT tests.7,8 Though these studies examined different populations — making direct comparisons difficult — Dr Limburg interprets the high adherence to Cologuard tests as a positive sign.

To Dr Yarden, the results underscore the importance of having access to home-based screening methods, since clinic-based methods such as colonoscopies are less acceptable to some individuals. “Because there is [the preparation] that everybody is afraid of, and then there’s the sedation, and then the intrusiveness,” and sometimes also financial considerations, she noted. (Some studies have reported adherence rates of 38.4% for colonoscopy-based screening.)8