Diagnostic utility of immunochemical fecal occult blood tests to detect lower gastrointestinal lesions in patients with chronic kidney disease.

PURPOSE: The immunochemical fecal occult blood test (iFOBT) is a useful method to screen for lower gastrointestinal (GI) bleeding-related lesions. However, few studies have investigated the diagnostic utility of iFOBT in chronic kidney disease (CKD).

METHODS: We included 691 patients with nondialysis-dependent CKD stages 2-5 or those receiving dialysis. Bleeding-related lower GI lesions were identified by colonoscopy, and the diagnostic utility of iFOBT was evaluated.

RESULTS: Bleeding-related lower GI lesions were found in 9.2% of 491 patients with CKD stage 2, 17.8% of 107 patients with CKD stage 3/4, and 25.8% of 93 patients with CKD stage 5/dialysis (p < 0.001). Compared with CKD stage 2, CKD stage 5/dialysis was independently associated with a 2.80-fold risk for bleeding-related lesions (p = 0.019). The iFOBT was positive in 92 (13.3%) patients and the area under the receiver operating curve (AUC) for a bleeding-related lesion was 0.64 (p < 0.001). The sensitivity of iFOBT increased as the CKD stage worsened (20.0 vs 52.6 vs 58.3%; p = 0.002). However, the specificity to detect bleeding-related lesions decreased with the severity of CKD stage (94.6 vs. 78.4 vs. 76.8%; p < 0.001). The AUC of iFOBT to detect adenoma or carcinoma was 0.54 (p = 0.046), and a similar pattern of sensitivity and specificity was observed between different CKD stages.

CONCLUSIONS: The prevalence of bleeding-related lower GI lesions and the sensitivity of iFOBT to detect these GI lesions increased in advanced CKD. However, iFOBT should be used cautiously in these patients because its specificity decreased.