1. Global tuberculosis report 2020. Geneva: World Health Organization; 2020 (https://apps.who.int/iris/ bitstream/handle/10665/336069/9789240013131-eng.pdf, accessed 19 February 2021).
2. Uplekar M, Weil D, Lönnroth K, Jaramillo E, Lienhardt C, Dias HM, et al. WHO’s new End TB Strategy. Lancet. 2015;385:1799–801. doi:10.1016/s0140–6736(15)60570–0.
Tuberculosis (TB) is a leading cause of death from a single infectious agent, despite being largely curable and preventable. In 2019 an estimated 2.9 million of the 10 million people who fell ill with TB were not diagnosed or reported to the World Health Organization (WHO). The Political Declaration adopted by the United Nations General Assembly in September 2018 at the High-Level Meeting on the Fight Against Tuberculosis commits to, among other goals, diagnosing and treating 40 million people with TB by 2022.
CRP is an indicator of general inflammation that can be measured using point-of-care tests performed on capillary blood collected via finger prick. The evidence reviewed for the performance of CRP included 6 studies from Kenya, South Africa and Uganda with a total of 3 971 participants (see Web Annex B, Table 13, and Web Annex C, Table 6).
Systematic screening in the general population is conducted on the premise that it bears dual benefit: to the persons diagnosed with TB and to the community in which screening is conducted. Individuals found to have TB may benefit from less diagnostic delay, improved treatment outcomes, and lower costs and financial losses associated with the disease. It also benefits public health by reducing the population prevalence of TB, thereby reducing further transmission of TB.
Case detection is a crucial step in the cascade of care for children with TB; however, for most children who die from TB, the disease is never diagnosed (80). Children and adolescents who are younger than 15 years represented approximately 12% of incident cases but 16% of the estimated 1.4 million deaths from TB in 2019 (1). This relatively higher share of mortality in children highlights the urgent need for improved case detection and subsequent access to preventive and curative treatment in this age group, particularly for those at highest risk.
TB remains the primary cause of AIDS-related morbidity and mortality worldwide, despite impressive scale up of antiretroviral treatment (ART). In 2019, TB was associated with an estimated 208 000 (30%) AIDS-related deaths (1). Global estimates show a 44% gap in case detection among people with HIVassociated TB (1). A systematic review of postmortem studies of global AIDS-related deaths in adults found TB to be the primary cause of death in 37.2% of cases (95% CI: 25.7–48.7). TB was undiagnosed prior to death in 45.8% of cases (95% CI: 32.6–59.1) (75).
The use of CXR to screen for TB is a practice that goes back several decades. CXRs are also routinely used for triage of patients presenting to care who are displaying signs, symptoms or risk factors for TB to determine the most appropriate clinical pathway for proper evaluation. However, in many settings, the use of CXR for TB screening and triage for TB disease is limited by the unavailability of trained health personnel to interpret radiography images and by substantial intra- and inter-reader variability in its accuracy to detect abnormalities associated with TB (70–72).
The data used to inform this recommendation came from a systematic review of the diagnostic accuracy of using symptoms and chest radiography to detect TB disease among individuals aged 15 years and older with negative or unknown HIV status. The review included studies of screening conducted in the general population (including several prevalence surveys conducted in African and Asian countries), as well as screening conducted in high-risk groups (including contacts of TB patients, prisoners and others).
This recommendation concerns interventions that should be undertaken in addition to passive casefinding practices, namely properly triaging and evaluating people seeking care who report signs or symptoms of TB, which should be done in all settings and is particularly important to implement rigorously among people who have risk factors for TB.
Several clinical characteristics, conditions and comorbidities can indicate an increased risk for developing TB disease or suffering worse outcomes from the disease, or both. Individuals identified as having untreated fibrotic lesions on CXR and who are not diagnosed with TB disease are at increased risk of developing TB disease (34–37). These individuals are often identified through TB screening or clinical evaluation or during a clinical evaluation done for other reasons.