Aysu YETİŞ, Selcen DURAN
Cyprus Journal of Medical Sciences - 2026;11(4):310-314
BACKGROUND/AIMS: Peripheral immune activity may contribute to Parkinson's disease (PD), but the clinical usefulness of blood cell-derived composite indices is not established. We compared the systemic immune-inflammation index (SII) and systemic inflammatory response index (SIRI) between patients with PD and healthy controls (HCs) and explored their relationships with disease stage, duration, and motor severity. MATERIALS AND METHODS: Data from 76 patients with PD and 44 HCs were evaluated in a cross-sectional case-control study. Disease severity was characterized using the Hoehn-Yahr (HY) stage and the motor section of the Unified PD rating scale (UPDRS). SII and SIRI were calculated from complete blood count parameters, and analyses were performed using non-parametric statistical methods. RESULTS: Patients with PD had higher SIRI and monocyte values and lower lymphocyte counts than HCs (p=0.008, p=0.047, and p=0.029, respectively). The groups were comparable with respect to neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and SII. No inflammatory index showed a significant relationship with HY stage, disease duration, or UPDRS motor score. CONCLUSION: An increased SIRI value may represent a peripheral inflammatory feature of PD. Nevertheless, the absence of group differences in NLR, PLR, and SII and the lack of associations with clinical severity indicate that this finding should not be interpreted as a marker of disease progression. Multicenter longitudinal research with adjustment for potential confounders is warranted.
