Background: Tuberculosis infection (TBI) and tuberculosis disease (TBD) incidence remains poorly described following household contact (HHC) rifampin-/multidrug-resistant tuberculosis exposure. We sought to characterize TBI and TBD incidence at one-year in HHCs and to evaluate tuberculosis preventive therapy (TPT) use in high-risk groups.

Methods: We previously conducted a cross-sectional study of HHCs of rifampin-/multidrug-resistant tuberculosis in 8 high-burden countries and re-assessed TBI (interferon-gamma release assay, HHCs ≥5 years) and TBD (HHCs all ages) at one-year. Incidence was estimated across age and risk groups (age <5 years; age ≥5 years, HIV-positive; age ≥5 years, HIV-negative/unknown, baseline TBI positive) by logistic or log-binomial regression fitted using generalized estimating equations.

Results: Of 1016 HHCs, 850 (83.7%) from 247 households were assessed (median: 51.4 weeks). Among 242 HHCs, 52 tested interferon-gamma release assay-positive, yielding a one-year 21.6% (95% CI 16.7-27.4) TBI cumulative incidence. Sixteen of 742 HHCs developed confirmed (n=5), probable (n=3) or possible (n=8) TBD, yielding a 2.3% (95% CI 1.4-3.8) one-year cumulative incidence (1.1% [95% CI 0.5-2.2] for confirmed/probable TBD). TBD relative risk was 11.5 (95% CI 1.7-78.7), 10.4 (95% CI 2.4-45.6), and 2.9 (95% CI 0.5-17.8) fold higher in age <5 years, HIV+, and baseline TBI high-risk groups, respectively, versus not high-risk group (p=0.0015). By one-year, 4% (21 of 553) high-risk HHCs received TPT.

Conclusions: TBI and TBD incidence continued through one-year in rifampin-/multidrug-resistant tuberculosis HHCs. Low TPT coverage emphasizes need for evidence-based prevention and scale-up, particularly among high-risk groups.

Keywords: household contacts; multidrug-resistant tuberculosis; tuberculosis disease; tuberculosis infection; tuberculosis preventive therapy.