Computed tomography findings, surgical findings, and histologic results were recorded for each patient when applicable. Study data were collected and managed using the REDCap electronic data capture tools hosted at Singapore General Hospital. REDCap (Research Electronic Data Capture) is a secure, web-based application designed to support data capture for research studies.11 In order PS-341 concentration to ensure short-term follow-up, all patients were reviewed in person by a clinician outpatient

at least once within 2 weeks from discharge. Subsequent follow-up visits were determined based on clinical indication. Patients discharged without surgery were treated with antibiotics only if they were diagnosed with conditions that warranted therapy. Empirical treatment with antibiotics was not practiced.

Repeat admissions for patients discharged without surgery were identified by a search of the National Electronic Health Record database in Singapore, a database Target Selective Inhibitor Library cost that captures the admission information of every person in Singapore who has visited the public health care system. A case of missed diagnosis was defined as readmission within 2 weeks from initial discharge, with eventual surgery showing acute appendicitis on histology. Appendicitis was considered present when patients who had undergone surgery had a final histology showing acute appendicitis. A case was considered to be a negative appendectomy when a patient had undergone surgery with the clinical impression of acute appendicitis but had no features of appendicitis in histology. Patients who did not undergo surgery were considered not to have appendicitis if they did not re-present within 2 weeks from initial discharge with acute appendicitis. Computed tomography scans were read by the radiologist on duty when the scans were ordered, and findings were categorized into 3 groups: positive for acute appendicitis,

negative for acute appendicitis, and click here equivocal findings. Sensitivity, specificity, positive and negative predictive values, and likelihood ratios were estimated for each of the cut off AS scores ranging from 2 to 10, using histology results as the gold standard. Scores of zero and 1 were omitted because there were no patients with such scores. The same diagnostic performance measures were calculated for CT scan using the same gold standard. Equivocal CT scans were considered positive for acute appendicitis in the calculations above. This method of classifying equivocal scans was chosen because in our institution, most surgeons would offer a diagnostic laparoscopy for patients who present with suspected appendicitis and an equivocal CT scan.