Can Baseline Distal Symmetric Neuropathy (DISINI) Score Predict Treatment Outcomes in Painful Diabetic Neuropathy?

Introduction: Vitamin D supplementation may help diabetic peripheral neuropathy (DPN) patients. Studies predicting vitamin D supplementation outcomes using assessment tools were still lacking. This study aimed to evaluate the benefit of vitamin D supplementations and the predictive value of the Distal Symmetric Neuropathy (DISINI) score in DPN. Methods: This is a two-armed, open-label, randomized clinical trial. The treatment group received standard treatment plus 5000 IU oral vitamin D, while the control group received standard treatment alone. The primary outcomes were Visual Analog Scale (VAS), Numerical Rating Scale (NRS), Brief Pain Inventory (BPI), and vitamin D levels. Regression analyses were performed to evaluate whether baseline DISINI scores could predict pain and vitamin D changes following supplementation. Results: We recruited 57 participants. The experimental group showed a greater decrease in mean VAS score (-3.22±1.54 vs -2.38±1.93), although not significant (p = 0.076; d = -0.48), while also having significant greater median vitamin D level change (27.45 (16.3, 33.18) vs 2.8 (-0.1, 4.7); p <0.001; rrb = 0.941). Paired-sample tests revealed a significant difference in NRS burning scores only in the experimental group (p = 0.008), while other variables, including VAS, NRS electric shock, NRS tingling, NRS numbness, and vitamin D levels, significantly differed in both experimental and control groups (p < 0.05). However, regression analysis revealed that baseline DISINI scores were not significant predictors of post-treatment pain outcomes or serum vitamin D levels (p >0.05). Conclusion: Vitamin D supplementation significantly improved pain severity and vitamin D levels in DPN patients, but baseline DISINI scores did not predict treatment outcomes. Further studies are needed to explore other potential predictors of treatment efficacy.