A blood-based 3-gene signature score for therapeutic monitoring in patients with pulmonary tuberculosis.

ABSTRACT

OBJECTIVE: To assess the validity of Xpert Tuberculosis Fingerstick score for monitoring treatment response and analyze factors influencing its performance. METHODS: 122 adults with pulmonary tuberculosis were recruited and stratified into three cohorts Diabetic-drug-susceptible-TB (DM-TB), Non-diabetic-drug-susceptible-TB (NDM-TB) and Non-diabetic Multidrug-resistant TB (MDR-TB). Fingerstick blood specimens were tested at treatment initiation (M0) and the end of the first (M1), second (M2), and sixth month (M6) to generate a TB-score. RESULTS: The TB-score in all participants yielded an AUC of 0.707 (95% CI 0.579-0.834) at M2 when its performance was evaluated against sputum culture conversion. In all non-diabetes patients, the AUC reached 0.88 (95% CI 0.756-1.000) with an optimal cut-off value of 1.95 at which sensitivity was 90.0% (95% CI 59.6-98.2%) and specificity was 81.3% (95% CI 70.0-88.9%). The mean TB score was higher in patients with low bacterial loads (n = 31) than those with high bacterial loads (n = 91) at M0, M1, M2, and M6, and was higher in non-cavitary patients (n = 71) than those with cavitary lesions (n = 51) at M0, M1, and M2. CONCLUSION: Xpert TB-score shows promising predictive value for culture conversion in non-diabetic TB patients. Sputum bacterial load and lung cavitation status have an influence on the value of TB score.