3.3 TB treatment and treatment coverage

Without treatment, the death rate from tuberculosis (TB) is high. Studies of the natural history of TB disease in the absence of treatment with anti-TB drugs (conducted before drug treatments became available) found that about 70% of people with sputum smear-positive pulmonary TB died within 10 years of being diagnosed, as did about 20% of people with culture-positive (but smear-negative) pulmonary TB (1). With TB treatment, most people who develop TB can be cured.

Effective drug treatments for TB were first developed in the 1940s. The composition of TB treatment regimens has changed over time and the currently recommended standard of care for people with drug-susceptible TB disease is a 6-month regimen of four first-line drugs: isoniazid, rifampicin, ethambutol and pyrazinamide (2). New evidence reviewed in meetings of WHO guideline development groups held in 2021 supports the use of two new 4-month treatment regimens for drug-susceptible TB that can be used as possible alternatives to the current standard 6-month regimen. Treatment for people diagnosed with drug-resistant TB (Section 3.4) requires regimens that include second-line drugs. These are longer, more expensive (≥US$ 1000 per person) and may cause more adverse events (3).

To minimize the ill health and mortality caused by TB, everyone who develops TB disease needs to be able to promptly access diagnosis and treatment. Providing TB diagnosis and treatment within the broader context of progress towards universal health coverage (UHC) is a key component of the WHO End TB Strategy, and is necessary to reach strategy milestones and targets for reductions in TB incidence and mortality (Section 2, Section 6). For example, reaching the 2025 milestone of a 75% reduction in the number of TB deaths compared with 2015 requires reducing the case fatality ratio (CFR; the percentage of people who develop TB that die from the disease) to 6.5%, which is only feasible if everyone who develops TB can access treatment. TB treatment coverage is one of the priority indicators for monitoring progress in implementing the End TB Strategy, with a recommended target of at least 90% by 2025 at the latest (4). TB treatment coverage is also one of 16 indicators used to assess progress towards the UHC target that has been set as part of the United Nations (UN) Sustainable Development Goals (SDGs) (5).

TB treatment coverage can be estimated as the number of new and relapse cases detected and treated in a given year, divided by the estimated number of incident TB cases in the same year, expressed as a percentage. Numbers of notified new and relapse cases (Section 3.1) are currently used as the numerator for the indicator, because these are the data available. However, limitations with this numerator are that there are people with TB who are treated but not notified to national authorities (and in turn are not notified to WHO) and people who are notified but who may not be started on treatment. Anyone with TB who is living with HIV should be provided with antiretroviral treatment (ART) as well as TB treatment; thus, for this group it is also relevant to assess the coverage of ART.

Globally in 2020, TB treatment coverage was 59% (95% uncertainty interval [UI]: 53–66%) (Fig. 3.3.1), down from 72% (UI: 65–80%) in 2019. Among the six WHO regions, treatment coverage was highest in Europe (with a best estimate of 69%) and lowest in the Eastern Mediterranean (with a best estimate of 52%). Of the 30 high TB burden countries, those with the highest levels of treatment coverage in 2020 included Brazil, China and Thailand (Fig. 3.3.1). The high value for Mozambique may reflect some overdiagnosis of cases that is inflating the numerator used in the estimation of treatment coverage; in 2020, only 35% of pulmonary cases were bacteriologically confirmed (Section 3.2). Nine high TB burden countries had worryingly low levels of treatment coverage in 2020, with best estimates of below 50%: Central African Republic, Gabon, Indonesia, Lesotho, Liberia, Mongolia, Nigeria, Pakistan and the Philippines.

In 2020, there was a big increase in the global gap between the number of people newly diagnosed and reported with TB and the number of people estimated to have developed TB. This reflects the sharp fall (of 18%) in the number of people newly diagnosed and reported with TB between 2019 and 2020 (from 7.1 million to 5.8 million) that has been associated with major disruptions to provision of and access to essential TB diagnostic and treatment services during the COVID-19 pandemic (Section 1). Ten countries accounted for 74% of the total estimated global gap between incidence and notifications in 2020 (Fig. 3.3.2), with India (24%), Indonesia (11%), the Philippines (8.3%), Nigeria (7.8%) and Pakistan (7.4%) accounting for more than half the global total.

The main reasons for a gap between notifications of people reported as newly diagnosed with TB and estimated TB incidence are:

• underreporting of detected TB cases – in many countries, levels of underreporting may be high; this is especially the case for those countries that lack policies on mandatory notification and other measures to ensure reporting of detected cases by all care providers; and
• underdiagnosis of people with TB – this can occur for reasons such as poor geographical and financial access to health care; delays in seeking health care because of lack of symptoms or symptoms not being perceived as serious enough to warrant a visit to a health facility; failure to test for TB when people do present to health facilities; and use of diagnostic tests that are not sufficiently sensitive or specific to ensure accurate identification of all people with TB.

It is also possible that the gap could be underestimated due to overdiagnosis, especially in settings where a relatively low proportion of TB cases are bacteriologically confirmed (Section 3.2).

Some of the countries with the largest estimated gaps between notifications and TB incidence already possess good evidence about the reasons for such gaps, and before the COVID-19 pandemic had achieved success in closing these gaps. For example, following studies that showed high levels of underreporting, India and Indonesia introduced policies on mandatory notification of TB cases, intensified engagement with care providers not yet reporting to national authorities, and established digital data systems to facilitate and simplify the reporting of cases. From 2013 to 2019 in India and from 2015 to 2019 in Indonesia, these actions resulted in marked increases in TB notifications (Section 3.1, Fig. 3.1.2).

An example of a country where underdiagnosis is a major challenge is Nigeria. The 2012 national TB prevalence survey found that 75% of the people with smear-positive pulmonary TB who were detected had symptoms that met national screening criteria but had not been previously diagnosed. This demonstrated a need to strengthen access to high-quality screening, diagnostic and treatment services. National TB prevalence surveys in many countries in Africa and Asia have also shown that detection and reporting gaps are systematically higher for men than for women (Section 2.3), suggesting that specific efforts are needed to improve access to TB diagnosis and treatment for men.

The global coverage of ART among people living with HIV who were also diagnosed and reported with TB was 88% in 2020, the same as the level in 2019 (Fig. 3.3.3). However, when compared with the estimated number of people living with HIV who developed TB in 2020, coverage was much lower (Fig. 3.3.4): the global average was 42%, down from 49% in 2019. Both figures were considerably worse than the overall coverage of ART for people living with HIV, which was 73% at the end of 2020 (6). The main reason for relatively low ART coverage among HIV-positive people with TB in 2020 was the big gap between the estimated number of people living with HIV who developed TB in 2020 and the number who were detected in 2020. Among the 30 high TB/HIV burden countries, best estimates of coverage varied widely, from 2.2% in Gabon to 79% in Mozambique, and only 13 of these 30 countries achieved coverage of at least 50% (Fig. 3.3.4).

Globally in 2019 (the latest annual patient cohort for which data are available), the treatment success rate for people treated for TB with first-line regimens was 86%, and ranged among WHO regions from 74% in the Americas to 91% in the Eastern Mediterranean (Fig. 3.3.5). This high level of overall treatment success has been sustained over a period of several years (Fig. 3.3.6). Treatment success rates remain lower among people living with HIV (77% globally in 2019), although there have been steady improvements over time (Fig. 3.3.6, Fig. 3.3.7). The treatment success rate for children (aged 0–14 years) was 88% in 2019 (Fig. 3.3.8). Treatment success rates have been maintained as the absolute number of people enrolled on treatment has grown (Fig. 3.3.9).

TB treatment and provision of ART to HIV-positive people diagnosed with TB are estimated to have averted 66 million deaths between 2000 and 2020 (Table 3.3.1).

Country-specific details about TB treatment and treatment coverage are available in the Global tuberculosis report app and country profiles.

Fig. 3.3.1 Estimated TB treatment coverage (new and relapse patients as a percentage of estimated TB incidence) in 2020, 30 high TB burden countries, WHO regions and globally

Fig. 3.3.2 The ten countries with the largest gaps between notifications of new and relapse (incident) TB cases and the best estimates of TB incidence, 2020^a

Fig. 3.3.3 Estimated global number of incident HIV positive TB cases (red) compared with the global number of notified new and relapse TB cases known to be HIV-positive (black) and the global number of TB patients started on antiretroviral therapy (blue), 2004–2020

Shaded area represents uncertainty intervals.

Fig. 3.3.4 Estimated coverage of antiretroviral therapy for HIV-positive TB cases (HIV-positive TB patients on antiretroviral therapy as a percentage of the estimated incidence of HIV-positive TB) in 2020, 30 high TB/HIV burden countries, WHO regions and globally

Fig. 3.3.5 Treatment outcomes for new and relapse TB cases in 2019, WHO regions and globally

Fig. 3.3.6 Treatment outcomes for new and relapse TB cases, globally, 2012–2019

Fig. 3.3.7 Treatment outcomes for new and relapse HIV positive TB cases in 2020, WHO regions and globally

Fig. 3.3.8 Treatment success rate for new and relapse TB cases in children aged 0–14 years in 2019, WHO regions and globally^a

Fig. 3.3.9 Treatment outcomes for new and relapse TB cases (absolute numbers), 2000–2019, globally and for WHO regions

Table 3.3.1 Cumulative number of deaths averted by TB and TB/HIV interventions 2000–2020 (in millions), globally and by WHO region