Prescription drugs associated with false-positive results when using faecal immunochemical tests for colorectal cancer screening

Background The most common side effect in population screening programmes is a false-positive result which leads to unnecessary risks and costs. Aims To identify factors associated with false-positive results in a colorectal cancer screening programme with the faecal immunochemical test (FIT). Methods Cross-sectional study of 472 participants with a positive FIT who underwent colonoscopy for confirmation of diagnosis between 2013 and 2014. A false-positive result was defined as having a positive FIT (≥20 μg haemoglobin per gram of faeces) and follow-up colonoscopy without intermediate/high-risk lesions or cancer. Results Women showed a two-fold increased likelihood of a false-positive result compared with men (adjusted OR, 2.3; 95%CI, 1.5–3.4), but no female-specific factor was identified. The other variables associated with a false-positive result were successive screening (adjusted OR, 1.5; 95%CI, 1.0–2.2), anal disorders (adjusted OR, 3.1; 95%CI, 2.1–4.5) and the use of proton pump inhibitors (adjusted OR, 1.8; 95%CI, 1.1–2.9). Successive screening and proton pump inhibitor use were associated with FP in men. None of the other drugs were related to a false-positive FIT. Conclusion Concurrent use of proton pump inhibitors at the time of FIT might increase the likelihood of a false-positive result. Further investigation is needed to determine whether discontinuing them could decrease the false-positive rate.