Utility of the immature granulocyte percentage for diagnosing acute appendicitis among clinically suspected appendicitis in adult.

BACKGROUND: Acute appendicitis is the most common cause of abdominal surgical emergencies that present at the emergency department (ED). Although early phase of acute appendicitis cannot induce systemic inflammatory responses, it may induce proliferation immature granulocyte before leukocytosis is occurred. Based on this, we hypothesized that IG% may be beneficial for detecting appendicitis, in addition to classic inflammatory markers including the WBC count, a left shift in neutrophils, and CRP, at no additional cost.

METHODS: A retrospective observational study was conducted in a tertiary-care, university-affiliated hospital emergency department in adults (>18 years old) with suspected appendicitis from January 1, 2015 to December 31, 2016. The diagnostic performance of IG% and other inflammatory markers, namely white blood cell (WBC) count, proportion of neutrophils, and C-reactive protein (CRP), for acute appendicitis was evaluated.

RESULTS: Of 403 patients, 204 (50.6%) were diagnosed with acute appendicitis and 45 (22.0%) had complicated appendicitis. All inflammatory markers, including WBC count, proportion of neutrophils, IG%, and CRP, were statistically different between the appendicitis and nonappendicitis group (P < .01). However, IG% was not clinically useful because the median IG% was the same (0.3 vs 0.3) between the appendicitis and nonappendicitis group. Moreover, the area under the curve for IG% was smaller than for other inflammatory markers (0.57, 0.51-0.63, P < .02).

CONCLUSION: The diagnostic ability of IG% for appendicitis is insufficient, and it brings no additional benefit over other inflammatory markers.