False-Positive Results in a Population-Based Colorectal Screening Program: Cumulative Risk from 2000 to 2017 with Biennial Screening
Menée en Espagne à partir de l'analyse des résultats de 130 134 tests de recherche de sang occulte dans les selles réalisés entre 2000 et 2017 auprès de 48 499 participants à un programme biennal de dépistage du cancer colorectal (âge : 50 à 69 ans), cette étude évalue le taux de faux positifs en fonction du type de test utilisé (test au gaïac ou test immunochimique) et de l'âge des patients
Background: The aim of this study was to estimate the cumulative risk of a false-positive (FP) result in a fecal occult blood test (FOBT) through 7 screening rounds and to identify its associated factors in a population-based colorectal cancer screening program.
Methods: Retrospective cohort study, which included participants ages 50 to 69 years of a colorectal cancer screening program in Catalonia, Spain. During this period, 2 FOBTs were used (guaiac and immunochemical). A discrete-time survival model was performed to identify risk factors of receiving a positive FOBT with no high-risk adenoma or colorectal cancer in the follow-up colonoscopy. We estimated the probability of having at least 1 FP over 7 screening rounds.
Results: During the period of 2000 to 2017, the cumulative FP risk was 16.3% (IC95%: 14.6%–18.3%), adjusted by age, sex, and type of test. The median number of screens was 2. Participants who began screening at age 50 years had a 7.3% [95% confidence interval (CI), 6.35–8.51] and a 12.4% (95% CI, 11.00–13.94) probability of an FP with 4 screening rounds of guaiac-based test and immunochemical test, respectively. Age, the fecal immunochemical test, first screening, and number of personal screens were factors associated with an FP result among screenees.
Conclusions: The cumulative risk of an FP in colorectal screening using FOBT seems acceptable as the colonoscopy, with its high accuracy, lengthens the time until additional colorectal screening is required, while complication rates remain low.
Impact: It is useful to determine the cumulative FP risk in cancer screening for both advising individuals and for health resources planning.
Cancer Epidemiology Biomarkers & Prevention , résumé, 2018