Differences between patients with inpatient- and outpatient-onset acute lower gastrointestinal bleeding: An observational study.

The clinical severity and course of acute lower gastrointestinal bleeding (ALGIB) are believed to differ between inpatient-onset and outpatient-onset cases, but no reports have investigated these issues in detail. We aimed to evaluate the clinical differences between inpatient- and outpatient-onset ALGIB.Medical records of patients who had undergone emergency colonoscopy for ALGIB were retrospectively reviewed. The severity was evaluated using the NOBLADS score. Patients with obvious ALGIB relapse and/or persistent iron-deficiency anemia after emergency colonoscopy were considered to exhibit a poor clinical course.We reviewed 723 patients with ALGIB and divided them into the inpatient-onset cohort (172 patients) and outpatient-onset cohort (551 patients). Compared with the outpatient-onset cohort, the inpatient-onset cohort had a significantly higher proportion of patients with a poor clinical course (51.2% vs 21.6%; P < 0.001) and a significantly higher mean NOBLADS score (3.6 ± 1.1 vs 2.5 ± 1.0; P < 0.001). The most common bleeding source was acute hemorrhagic rectal ulcer (52.3%) in the inpatient-onset cohort, and colonic diverticular bleeding (29.4%) in the outpatient-onset cohort. Multivariate analysis showed that a platelet count <15 × 104 /μL and albumin concentration <3 g/dL were significantly associated with a poor clinical course in the inpatient-onset cohort.The clinical course was significantly worse in the inpatient-onset cohort than in the outpatient-onset cohort. The bleeding source, clinical characteristics, and clinical course differed between the inpatient- and outpatient-onset cohorts. The clinical course in the inpatient-onset cohort may depend on the patient's condition at ALGIB onset.