The role of Vitamin D deficiency in neuropathic pain following Herpes Zoster: a retrospective cohort study

significantly impacts quality of life. In this context, the objective of this study is to investigate the relationship between serum 25-hydroxyvitamin D [25(OH)D] levels and the severity, duration, and neuropathic symptoms of PHN. Material and Methods: The sample of this retrospective observational cohort study consisted of 71 patients who were followed up with a diagnosis of PHN between January 2020 and June 2024. Patients were stratified into three groups according to their serum 25(OH)D levels as patients with vitamin D deficiency (≤20 ng/mL, n=24), vitamin D insufficiency (21-29 ng/mL, n=26), and vitamin D sufficiency (≥30 ng/mL, n=21). Patients’ neuropathic pain was assessed using the Douleur Neuropathique 4 (DN4) questionnaire and the Numeric rating scale (NRS). Inflammatory parameters such as C-reactive protein (CRP) level, erythrocyte sedimentation rate (ESR), and leukocyte count were recorded for each patient, and the diagnostic performance of their serum 25(OH)D levels was evaluated by receiver operating characteristic (ROC) curve analysis. Results: The mean DN4 and NRS scores and pain duration of the patients with vitamin D deficiency were significantly higher than those of other patients (5.83±1.76 vs. 1.71±0.96, p