Convergence of non-communicable diseases and tuberculosis: a two-way street?

Abstract

The intersection of tuberculosis (TB) with non-communicable diseases (NCDs), including diabetes mellitus (DM), chronic lung disease (CLD), and cardiovascular disease (CVD), has emerged as a critical clinical and public health challenge. Rapidly expanding NCD epidemics threaten TB control in low- and middle-income countries, where the prevention and treatment of TB disease remain a great burden. However, to date, the notion that TB may adversely impact NCD risk and severity has not been well explored. This review summarizes biomedical hypotheses, findings from animal models, and emerging epidemiologic data related to the progression of DM, CLD and CVD during and after active TB disease. We conclude that there is sufficient empirical evidence to justify a greater research emphasis on the syndemic interaction between TB and NCD.

Figure 1.. Conceptual framework for increased risk of non-communicable disease after active tuberculosis

Before treatment (Stage 1), TB disease results in symptoms, acute inflammation, and may result in transient hyperglycemia. During later phases of TB disease and during TB treatment (Stage 2), symptoms experienced during early stages may result in dyslipidemia, respiratory impairment, and hyperglycemia. In some patients, the Stage 2 symptoms may result in increased risk of chronic non-communicable disease after TB treatment (Stage 3). All arrows represent non-deterministic pathways; the likelihood of variables at the heads of arrows are hypothesized to be probabilistically increased by variables at the arrow’s tails.

Figure 2.

Patients with TB and newly indicated pre-diabetes or diabetes at time of TB treatment initiation who reverted to normal blood glucose levels during TB treatment

Figure 3.. Hypothetical trajectories of blood glucose levels over the natural history of TB

Among patients that experience TB-induced transient hyperglycemia, it is unknown what factors facilitate reversion to pre-TB blood glucose levels after TB treatment completion (Trajectory type 2) and what factors increase the likelihood of remaining elevated (Trajectory type 3) or later developing incident diabetes (Trajectory type 4).