Objective: In 1990, Lavelle and Kanagaratnam introduced Usefulness Index (UI) test for assessment of usefulness of clinical observations. Although, nonspecific abdominal pain (NSAP) is the most common diagnosis among secondary care patients with acute abdominal pain, the efficiency of UI test is rarely considered in NSAP.
Methods: In an extension of the World Organisation of Gastro-Enterology Research Committee (OMGE) acute abdominal pain study, 1333 patients presenting with acute abdominal pain were included in the study. The clinical signs (n = 14) and tests (n = 3) in each patient were recorded in detail, using a predefined structured data collection sheet, and the collected data were compared with the final diagnoses of the patients.
Results: The most significant clinical tests and signs of NSAP in univariate analysis were (UI = Usefulness Index and RR = risk ratio): rigidity (UI = 0.36, RR = 32.2), rebound (UI = 0.33, RR = 6.3), guarding (UI = 0.25, RR = 4.9), Murphy's positive (UI = 0.13, 8.9), bowel sounds (UI = 0.12, RR = 3.3), and renal tenderness (UI = 0.12, RR = 2.2). The sensitivity of the doctors' initial decision in detecting NSAP was 0.70 with a specificity of 0.83 and with the UI = 0.37 and RR = 11.4.
Conclusion: The patients with negative test results in rigidity, rebound, guarding, Murphy's, and bowel sounds tended to be at risk for NSAP and in these patients the UI test could be an aid for clinician to differentiate NSAP from other causes of acute abdominal pain.