Systemic inflammatory index correlates with cerebral small vessel disease in Parkinson's disease.

Background: This study investigates the association between systemic inflammatory indices-specifically, the systemic immune inflammation index (SII) and systemic inflammation response index (SIRI)-and the severity of cerebral small vessel disease (CSVD) in patients with Parkinson's disease (PD). Methods: A total of 167 patients with primary PD and complete MRI data were included. CSVD severity was assessed using total and modified CSVD burden scores, with patients categorized into two groups: mild (scores 0-1 or 0-2) and moderate-severe (scores 2-4 or 3-6). Logistic and ROC analyses were employed to evaluate the association and discriminative ability of SII and SIRI for CSVD severity. Results: Among 167 patients (59.3% male, mean age 69.6 ± 8.7 years), 91 and 96 were classified with moderate-severe CSVD based on total and modified scores, respectively. Higher SII and SIRI levels, along with a greater proportion of hypertension, were observed in the moderate-severe CSVD group. Spearman analysis indicated SII weakly correlated with both CSVD scores (total: Conclusion: Although their individual discriminatory abilities are limited, elevated SII and SIRI are independently associated with more severe CSVD in PD patients.