120 Fecal Immunochemical Test Performance Over Multiple Rounds of Annual Testing in an Outreach Screening Program

Abstract

One sample quantitative FIT kits (either NS-Plus Chemistry analyzer, Alfresa Pharma Corp., Japan or OC-Sensor DIANA IFOB Test System, Eiken Chemical Company Ltd., Japan) were used. The primary outcome was return of a completed one sample FIT kit. Patients with positive results (≥75 ng hgb/mL) were recommended colonoscopy. The primary outcome was compared by distribution method, return method and kit type using multivariate regression to adjust for patient, physician factors and kit type. Results Of the 3780 patients in our cohort, 685 (18%) returned a completed FIT kit. Of the 1839 that were mailed a kit, 436 (24%) returned it compared to 249 (13%) of the 1941 who were asked to visit their family physician to pick up a kit. Rates of return were similar in those who were asked to drop off a kit (330 of 1890 (18%)) and those who were asked to mail it back (344 of 1818 (19%)). After adjustment for kit type as well as patient and physician factors, FIT kit return was significantly associated with distribution method (single mail out vs. pick up: O.R. 2.97, 95% C.I. 2.04 4.32, p < 0.0001 and repeat mail out vs. pick up: O.R. 2.75, 95% C.I. 2.27 3.33, p < 0.0001) but not with method of return. 13.6% of participants had result of 75ng hgb/mL or greater while 10.9% had a result of 100 ng hgb/mL or higher. Positivity rates declined with increasing time from stool collection to testing. Conclusions Improved participation rates were associated with directly mailing the FIT kit but not with method of return. Our findings are of considerable interest to decision-makers in jurisdictions where FIT is being considered or is used in organized CRC screening.