Tuberculosis Comorbidity with Communicable and Noncommunicable Diseases

Abstract

The 18th WHO Global Tuberculosis Annual Report indicates that there were an estimated 8.6 million incident cases of tuberculosis (TB) in 2012, which included 2.9 million women and 530,000 children. TB caused 1.3 million deaths including 320,000 human immunodeficiency virus (HIV)-infected people; three-quarters of deaths occurred in Africa and Southeast Asia. With one-third of the world's population latently infected with Mycobacterium tuberculosis (Mtb), active TB disease is primarily associated with a break down in immune surveillance. This explains the strong link between active TB disease and other communicable diseases (CDs) or noncommunicable diseases (NCDs) that exert a toll on the immune system. Comorbid NCD risk factors include diabetes, smoking, malnutrition, and chronic lung disease, all of which have increased relentlessly over the past decade in developing countries. The huge overlap between killer infections such as TB, HIV, malaria, and severe viral infections with NCDs, results in a "double burden of disease" in developing countries. The current focus on vertical disease programs fails to recognize comorbidities or to encourage joint management approaches. This review highlights major disease overlaps and discusses the rationale for better integration of tuberculosis care with services for NCDs and other infectious diseases to enhance the overall efficiency of the public health responses.

Figure 1.

Estimates of population attributable to TB disease risk caused by HIV, undernutrition, smoking, diabetes, and alcohol abuse. AFR high HIV: African countries with high HIV prevalence. AFR low HIV: African countries with low/moderate HIV prevalence. CEUR: Central European countries. EEUR: Eastern European countries. EME: Established market economies. EMR: Eastern Mediterranean region. LAC: Latin American countries. SEAR: Southeast Asian region. WPR: Western Pacific region (except EME). Population attributable fraction (PAF) = [prevalence × (relative risk − 1)]/[prevalence × (relative risk − 1) + 1]. Point estimates of relative risk from systematic reviews were used. When prevalence was only available for adults, the prevalence in adults was adjusted for proportion of population under the age of 15 to estimate the total population PAF. HIV (human immunodeficiency virus infection): Relative risk = 27. Undernourishment (undernutrition): Relative risk = 3.2 (for BMI 16 vs. BMI 25). Diabetes (DM, diabetes mellitus): Relative risk = 3.1. Alcohol abuse: Relative risk = 2.9. Prevalence data: Average of prevalence of heavy drinking in China, Brazil, India, Nigeria, Pakistan, Russia, South Africa, and Thailand. Smoking (cigarette smoking): Relative risk = 2.0 (current vs. never smokers). (Adapted from Lönnroth et al. 2010 and Creswell et al. 2011.)