Do Anticoagulation or Antiplatelet Treatment Affect the Positive Predictive Value of iFOBT in Patients Undergoing Colorectal Cancer Screening? A Case-control Study

Purpose: The immunochemical fecal occult blood test (iFOBT) is the most used primary screening test for colorectal cancer (CRC) worldwide. A growing number of patients potentially targeted by CRC screening programs are on oral anticoagulant or chronic antiplatelet therapy, mainly for primary or secondary cardiovascular prophylaxis. Scanty and controversial results are reported in the literature as concerns diagnostic performances of iFOBT in this subset of patients. Present study is aimed to evaluate whether the chronic use of anticoagulation or antiplatelet therapies may affect the positive predictive value of iFOBT in a CRC screening scenario. Methods: From 2006 to 2008 all the iFOBT positive patients on anticoagulant or antiplatelet therapy recorded in a regional mass-screening program database were retrospectively enrolled in the study. The above treatments included warfarin and acetylsalicylic acid, ticlopidine or clopidogrel. Control groups were derived by the same database and included iFOBT positive patients matched in a ratio 1:2 for age (+/− 3 years of age), sex, site and date of colonoscopy for both anticoagulant and antiplatelet therapy. The positive predictive value of iFOBT for high and low-risk adenoma (HRA, LRA) and carcinoma (C) were calculated in the case and control groups. Proportions were compared by means of Chi-squared test. Results: Since 2006 to 2008, 2376 patients were recorded in the regional database. Of them, 53 (2%) were on anticoagulation (control group 106 patients) and 172 (6.6%) were on antiplatelet treatment (control group 344 patients). Main results for anticoagulant and antiplatelet therapy are shown in Table 1 and 2, respectively.Table 1Table 2Conclusion: The positive predictive value of iFOBT is not affected by ongoing anticoagulant or antiplatelet therapy. Therefore, according to the results of present study, these treatments should not be interrupted in patients undergoing iFOBT CRC screening.