Modified N score is helpful for identifying patients who need endoscopic intervention among those with black stools without hematemesis.

Objectives: Although black stools are one of the signs of upper gastrointestinal bleeding, not all patients without hematemesis need endoscopic intervention. There is no apparent indicator to select who needs treatment thus far. The aim of this study was to establish a novel score that predicts the need for endoscopic intervention in patients with black stools without hematemesis.

Methods: We retrospectively enrolled 721 consecutive patients with black stools without hematemesis who underwent emergency endoscopy from two facilities. In the development stage (from January 2016 to December 2018), risk factors that predict the need for endoscopic intervention were determined from the data of 422 patients by multivariate logistic regression analysis, and a novel scoring system, named the modified Nagoya University score (modified N score), was developed. In the validation stage (from January 2019 to September 2020), we evaluated the diagnostic value of the modified N score for 299 patients.

Results: Multivariate logistic regression analysis revealed four predictive factors for endoscopic intervention: syncope, the blood urea nitrogen (BUN) level, and the BUN/creatinine ratio as positive indicators and anticoagulant drug use as a negative indicator. In the validation stage, the area under the curve of the modified N score was 0.731, and the modified N score showed a sensitivity of 82.0% and a specificity of 58.8%.

Conclusions: Our modified N score, which consists of only four factors, can identify patients who need endoscopic intervention among those with black stools without hematemesis.