NLR, SII, and appendiceal diameter combination shows diagnostic accuracy for complicated appendicitis

This retrospective single-center diagnostic cohort study evaluated the preoperative differentiation between uncomplicated (UCAA) and complicated acute appendicitis (CAA) in 207 patients with pathologically confirmed appendicitis undergoing laparoscopic appendectomy. The study assessed the diagnostic accuracy of neutrophil-to-lymphocyte ratio (NLR), systemic immune-inflammation index (SII), and maximum appendiceal diameter, both individually and in combination.

For individual parameters, the area under the curve (AUC) was 0.863 for NLR, 0.803 for SII, and 0.815 for maximum appendiceal diameter. The combination of all three parameters achieved an AUC of 0.891 (95% CI: 0.840–0.942), with a sensitivity of 86.54% and specificity of 80.65% for differentiating CAA from UCAA. No comparator was reported for these diagnostic measures.

Safety and tolerability data were not reported. Key limitations include the retrospective, single-center design and lack of external validation. The study population consisted entirely of patients who underwent laparoscopic appendectomy, which may introduce selection bias. Funding and conflicts of interest were not reported.

For practice, these findings suggest that combining NLR, SII, and appendiceal diameter measurements may potentially aid individualized treatment planning and reduce diagnostic uncertainty in appendicitis. However, the retrospective nature and single-center setting limit generalizability, and these results should be interpreted as preliminary associations requiring prospective, multicenter validation before influencing clinical decision-making.