Diagnostic accuracy of the index finger vein inspection (‘Zhiwen’) for assessing paediatric pneumonia severity

OBJECTIVE: To determine the diagnostic accuracy and inter-rater reliability of the traditional index finger vein inspection ('Zhiwen') for assessing pneumonia severity in children. DESIGN: Cross-sectional diagnostic accuracy study adhering to Standards for Reporting of Diagnostic Accuracy Studies 2015 guidelines. SETTING: A tertiary paediatric referral hospital in Ho Chi Minh City, Vietnam. PATIENTS: 406 children aged ≤3 years with clinically diagnosed pneumonia were enrolled between March and May 2024. INTERVENTIONS: Participants underwent independent, blinded assessment by a paediatrician (reference standard: WHO pneumonia classification) and traditional medicine practitioners (index test: 'Zhiwen' inspection). Veins were classified into 'Wind', 'Qi' or 'Life' bars based on distal extension. MAIN OUTCOME MEASURES: Diagnostic accuracy metrics (sensitivity, specificity, predictive values, likelihood ratios) and inter-rater reliability (Cohen's kappa (κ)). RESULTS: Inter-rater reliability was excellent (κ=0.91; 95% CI 0.88 to 0.94). A significant graded association was observed between vein extension and pneumonia severity (p<0.001). The 'Life bar' extension was strongly associated with very severe pneumonia, demonstrating a sensitivity of 95.2% (95% CI 76.2% to 99.9%) and specificity of 96.4% (95% CI 94.0% to 98.0%). Crucially, the absence of the 'Life bar' yielded a negative predictive value (NPV) of 99.7%, effectively ruling out critical illness. CONCLUSION: The traditional 'Zhiwen' inspection is a reproducible and valid physical biomarker for pneumonia severity. Its high NPV suggests its potential as a rapid, no-cost adjunctive tool for risk stratification in children with established pneumonia in resource-constrained settings.