Risk Factors Associated With Tuberculosis Infection Among Household Contacts of Patients With Microbiologically Confirmed Pulmonary Tuberculosis in 3 High Tuberculosis Burden Countries.

BACKGROUND

Although tuberculosis preventive therapy guidelines support testing for tuberculosis infection in household contacts (HHCs), this adds operational complexity and cost and has often been abandoned. To understand utility of testing, we determined prevalence and risk factors for tuberculosis infection and tuberculosis preventive therapy eligibility among HHCs.

METHODS

In a cross-sectional study conducted from July 2021 to September 2022 in Lesotho, South Africa, and Tanzania, we enrolled people with microbiologically confirmed pulmonary tuberculosis and their HHCs. HHCs were screened and tested for tuberculosis and tuberculosis infection using Xpert Ultra and QuantiFERON-TB-Gold-Plus, respectively. Generalized linear modelling was used to determine factors associated with tuberculosis infection, using robust standard errors. Tuberculosis preventive therapy eligibility was determined using World Health Organization criteria.

RESULTS

We enrolled 342 people with pulmonary tuberculosis and 964 HHCs: 61.9% (597/964) were female with a median age of 18 years (interquartile range, 8-39 years). Overall, tuberculosis prevalence was 3.4% (25/739; 95% confidence interval [CI], 2.2%-4.9%), while tuberculosis infection prevalence was 48.7% (348/714; 95% CI, 45.0%-52.5%). Having tuberculosis infection increased with age per year (adjusted odds ratio [aOR], 1.02; 95% CI, 1.01-1.03), being from Lesotho (aOR, 1.82; 95% CI, 1.04-3.20), previous tuberculosis history (aOR, 2.25; 95% CI, 1.05-4.79), and being HIV negative (aOR, 2.30; 95% CI, 1.31-4.04). Overall, 62.2% (518/833; 95% CI, 58.8%-65.5%) were eligible for tuberculosis preventive therapy.

CONCLUSIONS

Almost half of tuberculosis-exposed HHCs aged ≥5 years had tuberculosis infection. Approximately two-thirds of HHCs were eligible for tuberculosis preventive therapy, implying that providing tuberculosis preventive therapy without prior testing for tuberculosis infection may be warranted in this population. Further work on cost-effectiveness is warranted when new tests become available.

CLINICAL TRIALS REGISTRATION: ISRCTN10003903.