Can the Modified Systemic Inflammation Score Predict Complicated Appendicitis?

To differentiate between complicated and uncomplicated acute appendicitis using the modified systemic inflammation score (mSIS) preoperatively. Observational study. Place and Duration of the Study: The Emergency Surgery Service of General Surgery Clinic of Ankara Bilkent City Hospital, Turkey, between 2021 and 2022. The study included 2,584 patients older than 18 years who underwent surgery with the diagnosis of acute appendicitis. Patients with malignant diseases and those younger than 18 were excluded. The patients' demographic characteristics, laboratory data, surgical notes, and pathology results were electronically obtained and analysed. According to the surgical findings and pathology records, gangrenous, perforated, and phlegmonous cases and those with any abscess focus were included in the complicated group and the remaining cases were included in the uncomplicated group. mSIS was evaluated as 0 if albumin was ≥4.0 g/dL and LMR (the lymphocyte-to-monocyte ratio) was ≥3.4, 1 if albumin <4.0 g/dL or LMR <3.4, and 2 if albumin <4.0 g/dL and LMR <3.4. mSIS was 0 in 868 (33.6%) cases and 1-2 in 1,716 (66.4%) cases. When the patients with mSIS values of 0 and 1-2 were compared, there was a statistically significant difference (p=0.03). mSIS 1-2 was found to have 85% sensitivity and 42% specificity in predicting complicated appendicitis. In addition, the probability of complicated appendicitis was 1.48 times higher among the patients with an mSIS of 1-2. Complicated appendicitis cases can be predicted preoperatively by simply calculating mSIS using the routine laboratory parameters. Complicated acute appendicitis, mSIS, Appendectomy.