Diagnostic accuracy of systemic immune-inflammation index for acute appendicitis in the geriatric population

Aims This study aimed to evaluate the diagnostic accuracy of the systemic immune-inflammation index (SII) in distinguishing acute appendicitis from non-appendicitis cases in geriatric patients who underwent surgery with a preliminary diagnosis of appendicitis. Methods A retrospective study was conducted on geriatric patients with suspected acute appendicitis at a tertiary healthcare center. Demographic data, clinical features, and laboratory values were obtained from medical records. The SII was calculated based on neutrophil, platelet, and lymphocyte counts, and the patients were classified according to histopathological outcomes. The primary outcome was the diagnostic accuracy of SII in identifying appendicitis in the elderly population. Results The study included 64 geriatric patients with suspected appendicitis, comprising 45 patients with confirmed appendicitis (70.3%) and 19 patients without appendicitis (29.7%). The mean age of the patients was 71 years (interquartile range: 67-76), with no significant difference between the appendicitis and non-appendicitis groups (p = 0.590). Females constituted 50% of the total cohort. The SII was significantly higher in the appendicitis group (median: 3687, interquartile range: 2420-5930) compared to the non-appendicitis group (median: 1589, interquartile range: 1134-2248, p < 0.001). The area under the receiver operating characteristic curve for the index was 0.81 (95% confidence interval: 0.68-0.93, p < 0.001), indicating good diagnostic accuracy. A threshold of greater than 2289 yielded a sensitivity of 0.78 and specificity of 0.79. The positive predictive value was 0.90, while the negative predictive value was 0.60. Conclusions The SII demonstrated high diagnostic accuracy in differentiating between acute appendicitis and non-appendicitis cases in geriatric patients. SII may be a valuable diagnostic tool in elderly patients with suspected appendicitis, aiding timely and accurate clinical decision-making.