Original Contribution Derivation of a clinical prediction rule for evaluating patients with abdominal pain and diarrhea Esther H. Chen MD ⁎ , Frances S. Shofer PhD, Anthony J. Dean MD, Judd E. Hollander MD, Jennifer L. Robey RN, Keara L. Sease MaEd, Angela M. Mills MD Department of Emergency Medicine, Hospital of the University of Pennsylvania, Philadelphia, PA 19104-4283, USA Received 11 July 2007; revised 27 July 2007; accepted 30 July 2007 Abstract Objective: The objective of the study was to develop a simple prediction rule to reliably identify abdominal pain patients with diarrhea who may require surgical intervention. Methods: We performed a secondary analysis of a prospective cohort study of adults with acute nontraumatic abdominal pain and diarrhea in an urban emergency department (ED). Structured data collection included 109 historical and 28 physical examination items, laboratory and radiographic results, and final diagnosis. The main outcome was operative intervention. Results: One thousand patients were enrolled; 174 patients with diarrhea were included in this analysis. Patients had a mean age of 39 ± 16 years and were likely to be female (64%) and black (60%). Fifteen (9%) patients received a surgical intervention from the ED. Clinical variables associated with the need for surgical intervention using univariate analysis were age older than 40 years, constant pain, and peritonitis on examination. Using recursive partitioning multivariate analysis, the derived prediction rule included 2 variables: age older than 40 years and constant pain. This rule had a sensitivity of 1.0 (95% confidence interval, 0.78-1.0) and specificity of 0.23 (95% confidence interval, 0.16-0.30). Conclusion: Patients older than 40 years with constant abdominal pain and diarrhea are likely to have a surgical cause of their symptoms. © 2008 Elsevier Inc. All rights reserved. 1. Introduction Acute abdominal pain, responsible for 6.8% of total visits, is the most common presenting symptom of emergency department (ED) patients [1] and has a broad differential diagnosis, including benign and life-threatening diseases. The classic teaching in surgical and emergency medicine textbooks is that abdominal pain with concurrent diarrhea suggests a diagnosis of gastroenteritis, infectious etiology, or if chronic and recurrent, inflammatory bowel disease [2,3]. Diarrhea, however, does not entirely exclude a surgical abdomen. In a retrospective study of ED patients with appendicitis, 22% had abdominal pain and diarrhea [4]. In another study of ischemic colitis diagnosed by surgical pathology, 38% of the patients presented with diarrhea, sometimes without any accompanying pain [5]. The variability of symptoms and clinical features of many serious causes of abdominal pain has led to many physicians relying heavily on diagnostic testing. In one ED study, 65% of patients with undifferentiated nontraumatic abdominal ⁎ Corresponding author. Tel.: +1 215 349 8506; fax: +1 215 662 3953. E-mail address: esther.chen@uphs.upenn.edu (E.H. Chen). www.elsevier.com/locate/ajem 0735-6757/$ – see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.ajem.2007.07.023 American Journal of Emergency Medicine (2008) 26, 450–453