Philadelphia, Pennsylvania - Patients who received positive fecal blood test results as part of the screening process for colorectal cancer experienced wide variations in the time between a positive result and a follow-up colonoscopy across four U.S. health care systems, according to a study published in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research.

“Fecal blood testing is one of the recommended strategies for colorectal cancer screening, but it works only when positive tests are followed up with a colonoscopy,” said the study’s lead author, Jessica Chubak, PhD, an associate investigator with Group Health Research Institute in Seattle.

Chubak and colleagues studied data from four U.S. health care systems, which were selected to provide a geographically and ethnically diverse study population. The study evaluated 62,384 patients, all of whom were between 50 and 89 years old and had received a positive result from a fecal blood test between Jan. 1, 2011, and Dec. 31, 2012.

The researchers found significant variation across health care systems in the median number of days between the positive fecal blood test and the colonoscopy: 41, 47, 84, and 174 days. The probability of a patient having a colonoscopy performed within a year ranged from 58.1 percent to 83.8 percent.

Chubak and fellow researchers also discovered that the oldest patients, those between 70 and 89 years old, were at the highest risk of not receiving a follow-up colonoscopy. Follow-up rates were also lower for patients who had never before been tested for colorectal cancer, and for those with comorbid conditions.

Chubak’s study did not examine all factors influencing follow-up time, but she said previous research in other settings indicates that lack of referrals and patient nonadherence are believed to be among them.

The four health care systems evaluated in this study were: Group Health, Kaiser Permanente Northern California, Kaiser Permanente Southern California, and Parkland Health and Hospital System, University of Texas Southwestern Medical Center. Chubak noted that the systems that had the shortest follow-up times used organizational strategies such as setting ambitious targets for follow-up, reporting results to leadership, and contacting patients who had not scheduled follow-up colonoscopies. The system with the longest follow-up time was a public health system whose patients may have faced personal or socioeconomic barriers to successfully continuing the screening process.

“We noticed in all four health systems that most patients who received a follow-up colonoscopy did so within six months of their positive fecal blood test,” Chubak said. “It is important for providers or health care systems to know that if a patient hasn’t received a colonoscopy within six months of a positive fecal blood test, they are unlikely to in the future—at least not without some further intervention.

“Understanding the variability in follow-up colonoscopy after a positive fecal blood test may help health care providers and systems identify patients in need of targeted interventions to complete follow-up,” Chubak continued.

Chubak said the primary limitation of the study is that it did not determine whether delays in getting colonoscopies affected colorectal cancer mortality. She said future research will examine whether patients’ outcomes were affected by varying follow-up times.

“Ultimately, that information will be critical for making the colorectal cancer screening process as effective as possible,” Chubak said.

This study was funded by the National Cancer Institute. Chubak declares no conflicts of interest.