Derivation of a clinical prediction rule for evaluating patients with abdominal pain and diarrhea.

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.