Neutrophil-to-lymphocyte ratio predicts infusion-site skin nodules in Parkinson’s disease patients receiving foslevodopa/foscarbidopa subcutaneous infusion

Abstract Continuous subcutaneous foslevodopa/foscarbidopa infusion (LDp/CDp-CSI) is an effective treatment for patients with Parkinson’s disease (PD), but infusion-site nodules are a major cause of treatment discontinuation. Systemic inflammation can influence local skin tolerance; however, predictive biomarkers remain unidentified. To evaluate the predictive value of the neutrophil-to-lymphocyte ratio (NLR) for clinically significant infusion-site nodules (PD-CSN) during LDp/CDp-CSI and to establish a clinical management framework to mitigate their development. We prospectively followed 38 patients with PD initiating LDp/CDp-CSI for ≥ 3 months. Baseline immunological data were collected before infusion. A subset of 30 patients was followed for an average of 11 months to identify factors associated with skin nodules at longer follow-up. Nodules were classified by blinded raters. Between-group comparisons, ANCOVA, ROC curve, and Kaplan-Meier analyses were performed. At 3 months, 42% of patients were PD-CSN and showed higher baseline neutrophil counts ( P = 0.030) and NLR ( P = 0.007), with NLR remaining independently associated with nodule status (F = 7.06, P = 0.012). ROC analysis demonstrated acceptable discrimination (AUC = 0.73, P = 0.016). At last follow-up, lower baseline lymphocyte counts ( P = 0.002) and higher NLR ( P = 0.001) were observed in PD-CSN. High baseline NLR predicted earlier nodule onset ( P = 0.001). Despite frequent nodules, multidisciplinary team surveillance, including remote and in-person follow-up, limited treatment discontinuation to 5.3%. Baseline systemic inflammation, reflected by NLR, predicts both the onset and persistence of infusion-site nodules during LDp/CDp-CSI. NLR may serve as a clinically accessible biomarker for early risk stratification. Multidisciplinary surveillance facilitates timely nodule management and enhances treatment adherence.