Estimating the Burden of Tuberculosis in India: A Modelling Study

Area of Science:

• Epidemiology
• Mathematical Modeling
• Public Health

Background:

• Tuberculosis (TB) incidence and mortality measurements are vital for tracking progress toward Sustainable Development Goals (SDG).
• Previous TB burden estimates in India relied on simpler models using limited state-level data.
• Recent national surveys and interventions provide opportunities for updated national and sub-national TB estimates.

Purpose of the Study:

• To develop and apply a refined mathematical model for estimating TB incidence and mortality in India.
• To account for India's healthcare system and COVID-19 disruptions in TB burden estimation.
• To provide updated national TB estimates for 2022.

Main Methods:

• A compartmental, deterministic mathematical model was developed, incorporating TB natural history and healthcare-seeking behaviors in India.
• The model was adapted from the WHO's global TB Report 2022 methodology, with added impact of the 2021 COVID-19 delta wave.
• Data sources included the National TB Prevalence Survey, public and private sector caseload trends, and mortality data.

Main Results:

• Estimated TB incidence in 2022 was 2.77 million, a decrease from 2.97 million in 2015.
• Estimated TB mortality in 2022 was 0.32 million, a decrease from 0.36 million in 2015.
• TB incidence rates per 100,000 population decreased from 225 in 2015 to 196 in 2022; mortality rates decreased from 27 to 23 respectively.

Conclusions:

• Mathematical modeling effectively integrates diverse data sources for robust TB burden estimation.
• While TB incidence estimates align with WHO figures, mortality estimates differ due to calibration targets using in-country data.
• Improving the quality and coverage of medically certified cause-of-death data is crucial for accurate mortality assessment in India.