Background: International guidelines recommend monitoring weight as an indicator of therapeutic response in childhood tuberculosis (TB) disease. This recommendation is based on observations in adults. In this study, we evaluated the association between weight change and treatment outcome, the accuracy of using weight change to predict regimen efficacy, and whether successfully treated children achieve catch-up weight gain.

Methods: We enrolled children treated for drug-susceptible TB disease (Group 1) and multidrug-resistant TB disease (Group 2) in Peru. We calculated the change in weight-for-age z-score (WAZ) between baseline and the end of treatment months 2-5 for Group 1, and between baseline and months 2-8 for Group 2. We used logistic regression and generalized estimating equation (GEE) models to evaluate the relationship between WAZ and outcome. We plotted receiver operating characteristic curves to determine the accuracy of WAZ for predicting treatment failure/death.

Results: Groups 1 and 2 included 100 and 94 children, respectively. In logistic regression, lower WAZ in months 3-5 and month 7 was associated with treatment failure/death in Groups 1 and 2, respectively. In GEE models, children in both group who experienced treatment failure or death had lower WAZ than successfully treated children. WAZ predicted treatment failure/death with 60-90% sensitivity and 60-86% specificity in months 2-5 for Group 1 and months 7-8 for Group 2. All successfully treated children—except Group 2 subjects with unknown microbiologic confirmation status—achieved catch-up weight gain.

Conclusions: Weight change early in therapy can predict outcome of childhood TB treatment.