Barriers to Follow-Up Colonoscopy After Positive FIT or Multitarget Stool DNA Testing

Discussion

CRC screening is recommended for all adults and has been shown to decrease the incidence and mortality from CRC. Current guidelines offer patients and providers a choice between different options.^2⇓–4 The stool-based tests, including FIT and mt-sDNA are specifically targeted for patients who prefer an alternative to colonoscopy or in whom colonoscopy would be difficult. The positive predictive value (PPV) of FIT testing for cancer is 2% to 11% and in a retrospective analysis, the PPV for detecting advanced neoplasia (advanced adenomas or cancer) was 24%.¹⁹ In the largest clinical trial of mt-sDNA testing, the PPV for advanced neoplasia was 24%.²⁰ Thus, it is important that patients with positive testing undergo appropriate evaluation with colonoscopy to detect and remove underlying neoplasia. The US Multisociety Task Force on Colorectal Cancer has recommended a minimum of 80% of patients have a follow-up colonoscopy after a positive FIT⁶ though similar guidelines for mt-sDNA are not in place.

In our study, which included patients from a vertically integrated health system, we found that compliance with follow-up colonoscopy after a positive FIT was only 46.7% and although compliance was higher after a positive mt-sDNA test, it was 71.5%, not nearly the preferred 100%. The colonoscopy frequency after positive FIT was in the range of previous reports.^{7⇓⇓⇓–11} One small study in a multispecialty group practice found close to 100% follow-up after positive mt-sDNA,¹² but the findings may not be generalizable to other settings. Moreover, we found that a combination of provider and health system issues were more frequent barriers to colonoscopy completion than patient-related factors, especially after positive FIT. Although this finding was in contrast with a recent VA-based study that found patient cancellation of colonoscopy was the most frequent reason for lack of colonoscopy after positive stool testing,⁹ they also reported system and provider factors as common deterrents. In a qualitative study from Ontario, Canada, attribution of a positive FIT to other causes and patient fear of colonoscopy were the 2 most common identifiable reasons for lack of follow-up.¹⁸ A recently published qualitative that included patients from federally qualified health centers also identified fear as a barrier but also determined that communication about the need for colonoscopy, transportation and cost of the procedure were additional obstacles.²¹

Whereas patients who are inherently reluctant to have a colonoscopy may have self-selected themselves for noninvasive screening options, we found several additional barriers to completion. A common reason for lack of compliance with colonoscopy in our study was that despite having a direct endoscopy referral system, providers ordered a gastroenterology clinic referral before colonoscopy, which the patient often did not keep. Although for certain patients (ie, those on anticoagulants or with a history of anesthetic reactions or inflammatory bowel disease) the gastroenterologist may have required visits before undertaking colonoscopy, in many cases the visit may not have been necessary and created another level of complexity. In addition, the extra appointment may not have been feasible for certain patients who could not miss work or other responsibilities or had transportation difficulties. In contrast, a VA based study found that referral to gastroenterology actually facilitated colonoscopy completion,¹⁰ which suggests that barriers to colonoscopy in an individual health care setting should be assessed before proposing solutions. We also noted that although some providers did not refer patients because of concerns of competing comorbidities or evidence of recent colonoscopy, these issues may not have been addressed before stool testing. Another potential barrier is the out-of-pocket cost associated with colonoscopy, which is considered diagnostic if performed as a result of a positive stool test. Our database did not include the out-of-pocket costs that patients faced.

Although we found a higher rate of follow-up after positive mt-sDNA testing than with positive FIT testing, reasons for lack of follow-up were generally similar between the 2 modalities. Whereas the reasons for this difference in follow-up frequency could not be determined from this study, the differences persisted even after adjustment for demographic characteristics such as insurance coverage. However, there may also be unmeasured physician and/or patient biases as to which test was ordered. If mt-sDNA was more likely to be ordered than FIT for patients who were more motivated at baseline to complete the follow-up that could account for some of the observed differences. In addition, for both FIT and mt-sDNA, colonoscopy performed as a follow-up to a positive stool test is generally considered to be diagnostic as opposed to screening and potentially subject to coinsurance; this could create an additional barrier for low-income patients. Physicians may have also ordered FIT testing as a confirmatory test to assess gastrointestinal blood loss as opposed to a screening test. In addition, the manufacturer of mt-sDNA employs a patient navigator program that encourages patients to return the kits. Although the navigators do not facilitate follow-up with colonoscopy after positive tests, they may have previously emphasized the importance of appropriate follow-up.

Multiple clinical trials have also evaluated interventions to improve follow-up of positive FIT tests²² though similar studies have not been performed for mt-sDNA. Based on a systematic review, it seems that the use of patient navigators and providing reminders or performance data to providers have the greatest efficacy, though studies were often prone to bias and the effect size was only moderate. In Kaiser Northern California, a multistep system-level strategy that included standardized tracking, reminders and navigator use improved colonoscopy completion from 73% to 85%.²³ A consensus conference also supported patient navigation as an effective strategy to improve follow-up with colonoscopy.²⁴ Recent work in an indigent patient population in New Hampshire has found to use of navigators to promote colonoscopy screening was effective in more than 97% of patients²⁵ and cost effective in both public health programs and endoscopy center outreach.²⁶

We recognize several strengths and limitations of our study. The sample includes patients from a large, diverse patient population from a Midwestern academic health care system with an electronic medical record system that encompasses office notes, test results, and procedures. Limitations include ambiguity about reasons for lack of follow-up if not documented in the clinical notes, as well as potentially missing procedure notes if a colonoscopy was performed at an outside facility, not scanned into the patient’s chart and not documented in an office note. This was a particular concern for mt-sDNA. In addition, in certain scenarios the patient may not have known about the referral to gastroenterology or colonoscopy and could not be contacted. We also could not measure certain patient characteristics that may have been associated with follow-up, including educational level, income, and language barriers.

In summary, follow-up colonoscopy after positive stool testing was higher for mt-sDNA than FIT, which should be considered in the programmatic evaluation of noninvasive screening options. However, follow-up after both tests was less than ideal. In our cohort, factors attributable to the provider and system were as frequently encountered as reasons for lack of follow-up colonoscopy as patient factors. These findings reinforce the need for multi-level interventions to improve follow-up.²⁷