Population-level impact of shorter-course regimens for tuberculosis: a model-based analysis

Area of Science:

• Public Health
• Epidemiology
• Mathematical Modeling

Background:

• Global tuberculosis (TB) incidence reduction is slow despite control efforts.
• New shorter treatment regimens may improve completion but their population-level transmission impact is unclear.

Purpose of the Study:

• To model the population-level impact of hypothetical shorter TB treatment regimens on incidence and mortality.
• To assess the influence of partial treatment completion on TB transmission dynamics.

Main Methods:

• A dynamic TB transmission model was calibrated with global incidence, prevalence, mortality, and treatment success data.
• Relapse rates from partial treatment completion (one-third, one-half, two-thirds) were estimated from clinical trial data.
• Population-level incidence and mortality were projected over 10 years comparing 6-month to hypothetical shorter regimens.

Main Results:

• Four-month TB regimens showed a smaller projected incidence reduction (1.9%) compared to previous models (10%).
• A larger impact on TB mortality was observed (3.5% at 10 years), though still modest.
• Transmission impact was highly sensitive to treatment completion rates, with greater incidence reductions in settings with high default rates (25% over 6 months).

Conclusions:

• Shorter TB treatment durations have a modest effect on TB transmission, particularly in settings with high treatment completion.
• Novel regimens may offer greater benefits in reducing TB mortality and transmission in areas with significant patient default from care.