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Background

Cases of unnecessary screening and diagnostic tests have been reported in a variety of medical settings, ^1,2 ranging from commonly used tests such as CTs and MRIs to advanced genetic testing. ³ The provision of unnecessary services, including unwarranted or redundant testing, costs the U.S. health care system an estimated $201 billion annually. ⁴ It is therefore important to determine where unnecessary testing is occurring and also the factors associated with inappropriate use in order to lower health care costs. Given that complications can arise from testing procedures (e.g., perforation during a colonoscopy), it is also important to avoid unnecessary testing to improve patient care.

Follow-up colonoscopies for survivors of colorectal cancer are of particular interest. Among survivors, 28% to 50% have locoregional or distant cancer recurrence, and procedures such as a colonoscopy can identify abnormalities and increase patient survival. ⁵ One study showed that a follow-up colonoscopy reduced the risk of death by 43% for the group that received at least one test. ⁶ A significant amount of research has focused on the underutilization of follow-up colonoscopies. ^7–9 However, a growing body of evidence suggests that follow-up colonoscopies are often used more frequently than specified in medical guidelines, which define the optimal time interval for the next test after a normal colonoscopy finding to be three to five years. ^10–12

While a handful of studies have examined referrals for follow-up colonoscopies, even fewer have analyzed whether the results of the colonoscopy tests were positive or negative. ¹³ This knowledge gap is important to fill since rates of positive test results may yield information on whether colonoscopies are being given to patients who are at higher risk of cancer recurrence. This study combines Texas cancer registry data and Medicare claims to measure referral patterns of follow-up colonoscopies and to evaluate test results. Analysis of referrals illuminates the determinants of colonoscopies in colon cancer survivors; analysis of test results illuminates the benefit of such tests. By analyzing referral decisions and subsequent test results simultaneously, it is possible to understand whether patient and clinical factors are associated with test outcomes, as referring physicians might expect at the referral stage.

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