False-positive results in a population-based colorectal screening programme: cumulative risk from 2000 to 2017 with biennial screening
Menée en Espagne à partir de données portant sur 48 499 participants ayant subi entre 2000 et 2017 un ou plusieurs tests de recherche de sang occulte dans les selles dans le cadre d'un programme biennal de dépistage du cancer colorectal (âge : 50 à 69 ans), cette étude estime le taux cumulé de résultats faussement positifs après 7 sessions de dépistage, puis identifie les facteurs associés
Background: The aim of this study was to estimate the cumulative risk of a false-positive (FP) result in a faecal occult blood test (FOBT) through seven screening rounds, and to identify its associated factors in a population-based CRC screening programme.
Methods: Retrospective cohort study which included participants aged 50-69 years of a CRC screening programme in Catalonia, Spain. During this period, two FOBTs were used (guaiac and immunochemical). A discrete-time survival model was performed to identify risk factors of receiving a positive FOBT with no CRC or high risk-adenoma or CRC in the follow-up colonoscopy. We estimated the probability of having at least one FP over seven screening rounds.
Results: During the period 2000-2017, 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 two. Participants who began screening at age 50 had a 7.3% (95% 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 faecal immunochemical test, first screening and number of personal screens were factors associated with an FP result among screenees.
Conclusions: The cumulative risk of FP in CRC screening using FOBT seems acceptable as the colonoscopy, with its high accuracy, lengthens the time until additional CRC 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