To find correlation of Thwaites’ and Lancet scoring systems with the microbiological diagnosis of TBM

Abstract

Background: Tuberculous meningitis (TBM) is a severe form of extrapulmonary tuberculosis, causing significant global mortality and morbidity. Its diagnosis is challenging due to non-specific clinical presentation and limitations of conventional microbiological methods, highlighting the need for rapid diagnostic tools.

Aim: This study aimed to correlate TBM diagnoses from the Thwaites' and Lancet clinical scoring systems with microbiological confirmation, and to assess their utility in differentiating TBM from other sub-acute and chronic meningitis etiologies.

Methods: A cross-sectional study at SRMS-IMS, Bareilly, India, included 180 adult patients with suspected meningitis with CSF abnormalities. Patients underwent clinical evaluation using both Thwaites' and Lancet scoring systems. CSF samples were analyzed for TLC, protein, glucose, ADA, AFB/Gram stain, and rapid MGIT culture. Radiological investigations (chest X-ray, brain CT/MRI) were also performed. Statistical analysis used Mann-Whitney Test and Point-Biserial correlation.

Results: The cohort was predominantly female (55%) and aged 21-30 (28.33%), with common complaints being fever (93.33%) and headache (83.33%). All patients showed abnormal CSF (lymphocytic predominance, low glucose, high protein), but Gram stain and AFB smears were consistently negative. Rapid MGIT culture was positive in only 11.67% (21/180) cases. Thwaites' system diagnosed all 180 patients as TBM (mean score -2.85 ± 2.51). Lancet system classified most as possible TBM (85.00%) and 11.67% as definite TBM. A significant positive correlation was found between MGIT culture positivity and the Lancet system (r=0.424, p=0.001), but not with Thwaites' system (r=0.082, p=0.531).

Conclusion: Early TBM diagnosis can be achieved by combining clinical assessment, CSF analysis, radioimaging, and clinical diagnostic scores. Despite microbiological culture being the gold standard, its low positivity necessitates reliance on clinical suspicion and validated scoring systems for prompt anti-tubercular therapy (ATT) initiation. The Lancet scoring system showed superior utility in guiding clinical decisions for TBM management due to its stronger correlation with microbiological confirmation. ATT initiation should be based on a comprehensive evaluation integrating investigative findings with clinical judgment.