NDS and NSS for Screening Diabetic Neuropathy

This study is an analytic cross-sectional diagnostic accuracy study designed to evaluate the performance of the Neuropathy Disability Score (NDS) and Neuropathy Symptom Score (NSS) in screening for diabetic sensorimotor polyneuropathy.

Adult patients with diabetes mellitus (type 1 and type 2) will be recruited from King Chulalongkorn Memorial Hospital. Eligible participants will undergo a standardized assessment protocol, including demographic and clinical data collection, physical examination, and laboratory investigations. Patient-reported outcomes will be assessed using validated questionnaires, including the Neuropathy Symptom Score (NSS), Neuropathy Disability Score (NDS), DN4 questionnaire, Michigan Neuropathy Screening Instrument (MNSI), and other relevant clinical tools.

All participants will undergo nerve conduction studies (NCS), which will serve as the reference standard for the diagnosis of diabetic peripheral neuropathy. Additional assessments may include quantitative sensory testing (QST), monofilament testing, hand grip strength measurement, ankle-brachial index (ABI), and body composition analysis, depending on clinical indication.

The primary objective is to determine the diagnostic accuracy of NDS and NSS compared with the reference standard, including sensitivity, specificity, and optimal cutoff values. Secondary objectives include evaluating the prevalence of neuropathy among patients with diabetes, identifying associated risk factors, and comparing clinical characteristics between type 1 and type 2 diabetes.

Statistical analysis will include descriptive statistics, group comparisons using appropriate parametric or non-parametric tests, and receiver operating characteristic (ROC) curve analysis to determine diagnostic performance. Correlation analyses will also be performed to assess associations between clinical variables and neuropathy outcomes.

The findings from this study are expected to support the use of simple, cost-effective screening tools for early detection of diabetic peripheral neuropathy in clinical practice, particularly in resource-limited settings.

Inclusion criteria

• Adults aged 30 to 65 years
• Diagnosed with diabetes mellitus (type 1 or type 2) by a physician
• Able and willing to provide informed consent
• Willing to undergo clinical evaluation and neurophysiological testing, including nerve conduction studies

Exclusion criteria

• History of other causes of peripheral neuropathy (e.g., nutritional deficiency, alcohol-related neuropathy, chronic kidney disease)
• Known neuromuscular or neurological disorders (e.g., myopathy, hereditary neuropathy, Guillain-Barré syndrome, chronic inflammatory neuropathy)
• Exposure to neurotoxic agents (e.g., drugs, heavy metals)
• Presence of lower limb conditions interfering with assessment (e.g., amputation, chronic wounds, significant edema)
• Inability to communicate or complete study procedures