FREQUENCY OF PULMONARY TB POSITIVE CASES USING THE MODIFIED KENNETH JONES SCORING CRITERIA AND DIAGNOSTIC ACCURACY USING STOOL GENEXPERT AS THE REFERENCE STANDARD IN PEDIATRIC PATIENTS

Abstract

Objective: To evaluate the diagnostic accuracy of the modified Kenneth Jones Scoring Criteria (MKJSC) using stool GeneXpert as the reference standard for childhood pulmonary tuberculosis and describe the frequency of stool GeneXpert positivity in the study population.

Study design: Cross-sectional study.

Place & duration of the study: Department of Paediatric Medicine, The Indus Hospital, Karachi, from March 2025 to june 2025.

Methodology: Children with MKJSC score >2 were consecutively recruited, and stool samples were tested by GeneXpert for pulmonary TB. Data were collected through REDCap and analysed using SPSS version 26. Diagnostic performance of MKJSC was assessed using stool GeneXpert as the reference standard.

Results: A total of 205 children aged 1 month to 16 years were enrolled. Mean age was 5.08 ± 3.62 years, and 52.7% were male. MKJSC criteria identified TB in 110 (53.7%) children, out of which 15 (7.3%) were confirmed by stool GeneXpert. MKJSC (score ≥4.5) showed sensitivity of 73.3%, specificity of 48%, positive predictive value (PPV) of 10%, negative predictive value (NPV) of 96% and diagnostic accuracy of 50% (AUC = 0.644 [95%CI: 0.518-0.769]; p=0.064).

Conclusion: Compared with stool GeneXpert, MKJSC demonstrated moderate sensitivity and limited specificity, with an overall diagnostic accuracy of 50%. Its high NPV suggests potential utility as a screening tool to identify children unlikely to have pulmonary tuberculosis. However, microbiological confirmation remains essential whenever feasible.