Unrecognized Tuberculosis: Risk Factors for Smear-Positive/Cavitary Asymptomatic Cases

Area of Science:

• Public Health
• Infectious Diseases
• Epidemiology

Background:

• Screening asymptomatic active tuberculosis (TB) is vital for disease control due to transmission potential.
• Identifying transmission risk factors in asymptomatic TB patients is crucial for effective public health strategies.
• Understanding the impact of asymptomatic TB infectiousness on outcomes aids in developing targeted interventions.

Purpose of the Study:

• To identify factors associated with transmission risk in asymptomatic pulmonary TB patients.
• To determine the clinical outcomes, specifically mortality, in asymptomatic pulmonary TB patients stratified by transmission risk.
• To inform targeted screening strategies for asymptomatic TB.

Main Methods:

• Analysis of national Korean TB cohort data.
• Inclusion of 20,455 pulmonary TB patients, with a focus on 7,434 asymptomatic cases.
• Primary outcome: factors associated with transmission risk; Secondary outcome: mortality stratified by transmission risk.

Main Results:

• Factors associated with higher transmission risk included male sex, low body mass index (BMI), current smoking, diabetes, and autoimmune disease.
• Asymptomatic TB patients with transmission risk factors showed a higher mortality rate (9.3%) compared to those without (7.1%).
• A significant proportion of pulmonary TB patients (36.4%) were asymptomatic, with 25.5% exhibiting potential transmission risks.

Conclusions:

• Lean, smoking men with asymptomatic TB, particularly those with diabetes and/or autoimmune diseases, exhibit elevated transmission and mortality risks.
• Asymptomatic individuals with these identified risk factors require targeted screening efforts.
• These findings support the development of focused public health interventions to mitigate TB transmission and improve outcomes.