Sensitivity and Specificity of the Alvarado Score for the Timely Differential Diagnosis of Acute Appendicitis in Samoa

METHODS

Study Design and Data Collection

A retrospective study design was used to evaluate all AA cases seen by the Surgical Department of TTM Hospital over the 24-month period between 1 January 2015 and 31 December 2016. The clinical medical records were obtained from the National Health Service PATIS System, using the search terms 'appendicitis', 'acute appendicitis', and 'appendicectomy'. A total of 289 records were retrieved. Thirty four (34) records were excluded having met the exclusion criteria: (1) final diagnosis was not AA (i.e., ectopic pregnancy, tubal ovarian abscess, other gynaecological pathologies, diverticulitis, Merkel diverticulitis, perforated ulcer), and (2) appendiceal abscess and/or appendiceal mass. Thirty (30) clinical records with missing data, and these were also excluded from the study. The final number of included for analysis was 225 cases. All 225 cases were initially treated with intravenous antibiotics upon presentation to the emergency department as per the National Health Service antibiotic guidelines: intravenous ceftriaxone and metronidazole was the first line of treatment, and alternative antibiotics were administered if unavailable (i.e., clindamycin + gentamycin or ampicillin, or gentamycin + metronidazole).

A purpose-designed data collection form and excel spreadsheet were created for the study. The following information was extracted from the clinical records: patient gender (male/female), age (years), address (urban/rural), time of admission (Morning/Afternoon/Night Shift), use of traditional/alternative medicine prior to attending emergency department (yes/no), administration of antibiotics by emergency department staff (yes/no), Alvarado Score (1-10), Ultrasound Scan for AA (Positive/negative/Inconclusive/Not performed), management of AA (appendicectomy/antibiotic therapy), intra-operative macroscopic examination (Grade 1-5), histopathology result for AA (Positive/Negative/Inconclusive/Not available), length of stay in hospital (days), and mortality (yes/no).

Data analysis The data was analysed using the SPSS (Version 2.1) statistical software package. Descriptive analysis was performed, and the chi-square test of significance was used to investigate for statistically significant differences between variables (significant at p<0.05). The sensitivity, specificity, Positive Predictive Value (PPV), and Negative Predictive Value (NPV) were calculated for the Alvarado Score in identifying AA as confirmed by histopathology.