UCSF

Background & aims

The fecal immunochemical test (FIT) is an alternative to colonoscopy and can increase overall screening for colorectal cancer (CRC). However, little is known about the frequency of and reasons for mishandled FIT samples.

Methods

We performed a prospective study, nested within a randomized controlled trial of patients, recruited from December 2015 through August 2017, who were not up to date with colorectal cancer screening (50-75 years old). The patients were randomly assigned to usual care or outreach groups that received a mailed FIT with low literacy level instructions or a reminder call, or both. We examined frequency of and reasons for mishandled FIT samples, including absence of collection date; time from collection to laboratory receipt of more than 14 days; or mishandling of stool, buffer, or cap. The outcomes were the frequency of mishandled FIT samples, effects of outreach on mishandling, and positive results from the FIT among proper and mishandled samples.

Results

FIT samples were returned from 1871 patients assigned to usual care and 3045 who received the low literacy level instructions and a reminder call. In total, 19.8% of samples were mishandled; most of these (93.7%) had not labeled the date of stool collection but were still processed. Of the received samples, 1.2% of were not processed because the time from patient collection to laboratory receipt was more than 14 days. Outreach was associated with a lower proportion of mishandled samples (16.5% vs 25.0% for usual care; P < .0001). The proportion of mishandled samples was lowest among patients who received the low literacy level instruction and a reminder call (12.8%, P < .0001). There was no significant difference in proportions of positive results between properly processed samples (7.5%) and improperly processed samples (6.2%) (P = .14).

Conclusion

In a prospective study of patients who were not up to date with colorectal cancer screening, we found that almost 20% of FIT samples were mishandled, with most patients missing the stool collection date. Patient outreach was associated with a lower proportion of mishandled samples, but there was no difference in proportions of positive results between properly and improperly handled samples. Our findings indicate that routine processing of undated FIT samples is associated with similar rates of positive results. There are limited data on test characteristics for FIT samples beyond the 14 days of stool acquisition. The inclusion of low literacy level instructions with reminder calls was associated with improved patient handling of the FIT sample. ClincialTrials.gov no: NCT02613260.