Occult Blood in Feces Is Associated With an Increased Risk of Ischemic Stroke and Myocardial Infarction: A Nationwide Population Study

BACKGROUND: Although occult hemoglobin in feces is universally valued as a screening tool for colorectal cancer (CRC), only few studies investigated the clinical meaning of fecal immunochemical test (FIT) in other diseases. We evaluated the clinical utility of FIT in patients with cardiovascular diseases (namely, ischemic stroke and myocardial infarction [MI]). METHODS AND RESULTS: Using the National Health Insurance database, participants (aged >50 years) with CRC screening records from 2009 to 2012 were screened and followed up. Subjects with a history of cardiovascular diseases and CRC were excluded. Ischemic stroke, MI, and other comorbidities were defined by International Classification of Diseases, Tenth Revision (ICD‐10), codes. Age, sex, smoking, alcohol consumption, regular exercise, diabetes mellitus, hypertension, dyslipidemia, and body mass index were adjusted in a multivariate analysis. A total of 6 277 446 subjects were eligible for analysis. During the mean 6.79 years of follow‐up, 168 570 participants developed ischemic stroke, 105 983 developed MI, and 11 253 deaths were observed. A multivariate‐adjusted model revealed that the risk of ischemic stroke was higher in the FIT‐positive population (adjusted hazard ratio [HR], 1.09; 95% CI, 1.07–1.11). Similarly, FIT‐positive subjects were at an increased risk of MI (adjusted HR, 1.09; 95% CI, 1.06–1.12). Moreover, increased all‐cause mortality was observed in the FIT‐positive population (adjusted HR, 1.15; 95% CI, 1.07–1.23). The increased risk remained consistent in the stratified analysis on anemia and CRC status. CONCLUSIONS: Positive FIT findings were associated with ischemic stroke, MI, and mortality. Occult blood in feces may offer more clinical information than its well‐known conventional role in CRC screening.