1. Positive fecal immunochemical test (FIT) results were associated with increased incidences of ischemic stroke, myocardial infarction, and all-cause mortality.
Evidence Rating Level: 2 (Good)
While fecal immunochemical tests (FIT) is a commonly used and effective screening tool for colorectal cancer (CRC), their clinical use in detecting other diseases is poorly known. As cardiovascular diseases and CRCs share risk factors such as old age, smoking, and physical inactivity, these conditions may share an underlying pathogenesis (i.e. systemic inflammation). Therefore, FIT results may share some insight into cardiovascular morbidity and all-cause mortality. In this nationwide population-based cohort study, 6 277 446 participants (over 50 years old) with CRC screening records from 2009-2012 in the South Korean National Health Insurance database were included. Patients with a history of cardiovascular disease and/or CRC were excluded. Over a median follow-up of 6.79 years, incidence rates of both ischemic stroke (4.88 vs 3.90 per 1000 patient years) and myocardial infarction (2.99 vs 2.44 per 1000 patient years) were higher in the FIT-positive over the FIT-negative group. This increased risk of ischemic stroke (aHR 1.25, 95%CI 1.23-1.27) and MI (aHR 1.09, 95% CI 1.19-1.25) remained significant after adjusting for demographic, social history, and comorbidity factors. Additionally, FIT-positive results were associated with increased all-cause mortality (aHR 1.15, 95% CI 1.07-1.23). Furthermore, these associated risks remained positive regardless of CRC and/or anemia status. By demonstrating an association between FIT positivity and increased stroke, MI, and all-cause mortality, these findings support a role for FIT beyond CRC screening. Nonetheless, randomized controlled trials would be needed to establish any causal relationships; future studies should also evaluate antithrombotic use, a common cause of false positive FIT results, and be capable of distinguishing between first-time and recurrent cardiovascular events.
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