Risk of progression to pulmonary tuberculosis among household contacts with chest radiographic abnormalities in South Africa
Discuss this preprint
Start a discussion What are Sciety discussions?Listed in
This article is not in any list yet, why not save it to one of your lists.Abstract
Background
High-risk subgroups among household contacts of persons with tuberculosis (TB) might benefit from additional interventions. However, the significance of an abnormal baseline chest radiograph (CXR) suggestive of TB, despite negative sputum microbiology, is uncertain.
Methods
Adults (≥18 years) with recent household TB exposure were enrolled at three South African sites (April 2021– September 2022). All participants underwent symptom screening, CXR, and sputum Xpert Ultra and MGIT culture. Pulmonary TB diagnosis was microbiologically-confirmed. Participants without prevalent TB were followed for symptomatic incident TB through 12 months. Multivariable logistic regression identified factors associated with abnormal CXR suggestive of TB. Poisson regression estimated adjusted incidence rate ratios (aIRR) with 95% confidence intervals (95%CI).
Results
Baseline CXR were available for 795/846 (94.0%) participants without prevalent TB and were abnormal in 157/795 (19.7%); associated with older age (adjusted odds ratio, aOR=1.04, 95%CI 1.02–1.05); prior TB (aOR=6.39, 95%CI 4.18–9.78); and current smoking (aOR=1.61, 95%CI 1.00–2.62). Symptomatic incident TB developed in 8/795 (1.0%) participants, including 7/8 (87.5%) who were asymptomatic and 4/8 (50.0%) with abnormal CXR at baseline. TB incidence was higher in those with abnormal versus normal CXR (aIRR=4.11, 95%CI 1.29–13.09), but after median 12.1 (IQR 11.1–13.1) months follow-up, 153/157 (97.5%) had not progressed to incident TB.
Conclusions
Adult household contacts with CXR abnormalities, but without prevalent TB, had a four-fold higher incidence of TB within one year, compared to those with normal CXR. This additional risk warrants targeted preventive treatment and extended surveillance, but since most remained TB-free, therapeutic TB treatment is not justified.
Key points
Adult household contacts with abnormal CXR have four-fold increased risk of incident TB disease compared to those with normal CXR, supporting targeted preventive treatment and extended surveillance. However, since the vast majority remain TB-free, therapeutic TB treatment is not warranted.
