Predictors of Microbiologically Confirmed Intrathoracic Tuberculosis.

Objective: To identify risk factors for microbiologically confirmed intrathoracic tuberculosis in children.

Methods: Children, 6 mo to 15 y of age, attending the out-patient department of a tertiary care centre in India, with probable intrathoracic tuberculosis were enrolled. Microbiological confirmation of tuberculosis was defined as positivity on smear (Ziehl-Neelsen staining) and/or Xpert MTB/RIF and/or MGIT-960 culture. Association of various factors with microbiological confirmation were assessed by univariate and multivariate analysis.

Results: Microbiologic confirmation was documented in 39 (25%) of 153 patients enrolled. On univariate analysis, microbiological positivity was associated with female gender, higher mean (SD) age [136.6 (31.8) vs. 117.3 (41.4) mo], parenchymal lesion on chest radiograph, low body mass index for age, having symptoms of cough and weight loss, lower mean (SD) hemoglobin [10.4 (1.37) g/dl vs. 11(1.52) g/dl; p = 0.04], and higher mean (SD) monocyte: lymphocyte ratio [0.38 (0.30) vs. 0.24 (0.02); p = 0.37]. Higher proportion of microbiologically negative children were BCG vaccinated (95% vs. 79%; p = 0.002). On multivariate analysis, microbiological positivity showed significant association with low body mass index for age (p = 0.033) and higher monocyte: lymphocyte ratio (p = 0.037).

Conclusions: Low body mass index for age and higher monocyte: lymphocyte ratios were associated with microbiological confirmation in children with intrathoracic tuberculosis.