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.

The study is 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. After receiving a positive result, patients are generally referred for follow-up colonoscopies. This study revealed significant variation in the time between the positive fecal blood tests and the follow-up colonoscopies.

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. 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.

"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," Chubak said. "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."

The study did not determine whether delays in getting colonoscopies affected colorectal cancer mortality. Chubak said future research will examine whether patients' outcomes were affected by varying follow-up times.

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