1.3 Drug-resistant TB

Since 1994, the World Health Organization (WHO) has systematically collected and analysed data on levels of resistance to anti-TB drugs from countries and areas (1). Most attention has been given to the proportion of people diagnosed with TB who have rifampicin-resistant TB (RR-TB) and multidrug-resistant TB (MDR-TB, defined as resistance to both rifampicin and isoniazid), collectively referred to as MDR/RR-TB (for data sources and availability, see Box 1.3.1). Since 2022, new methods have been used to produce time series of estimates of the number of people developing MDR/RR-TB each year (incident cases), covering the period from 2015 up to the most recent complete calendar year (2, 3). Data on resistance to other anti-TB drugs are collected as well, but the country coverage of such data is much more limited.

Globally, the estimated annual number of people who developed MDR/RR-TB was relatively stable between 2020 and 2022, after a slow downward trend between 2015 and 2019 (Fig. 1.3.1). The estimated number in 2022 was 410 000 (95% uncertainty interval [UI]: 370 000–450 000). Compared with the time series published in the Global Tuberculosis Report 2022 (4), there was a downward revision for all years since 2015, for two main reasons: downward revisions to overall estimates of TB incidence (Section 1.1); and revisions to estimates of the proportion of people with TB who had MDR/RR-TB in several countries, most notably Pakistan (details are provided in Annex 5 of the main report).

Fig. 1.3.1 Global trend in the estimated number of people who developed MDR/RR-TB (incident cases), 2015–2022

Globally, MDR/RR-TB caused an estimated 160 000 (95% UI: 98 000–220 000) deaths in 2022.

The reason why the number of people developing MDR/RR-TB is not estimated to have increased from 2020–2022, in contrast to the number of people developing TB overall (Section 1.1), is that increases in the overall number of people developing TB have been compensated for by an estimated downward trend (since 2015) in the proportion of people with TB who have MDR/RR-TB, particularly among those with a previous history of treatment (Fig. 1.3.2).

Globally, the estimated proportion of new TB cases with MDR/RR-TB fell from 4.0% (95% UI: 3.1–4.9%) in 2015 to 3.3% (95% UI: 2.6–4.0%) in 2022; the estimated proportion of previously treated cases with MDR/RR-TB was 25% (95% UI: 15–36%) in 2015 and 17% (95% UI: 11–23%) in 2022.

Fig. 1.3.3 Regional trends in the estimated number of people who developed MDR/RR-TB (incident cases), 2015–2022

Trends in the 30 high MDR/RR-TB burden countries also vary (Fig. 1.3.4).

Fig. 1.3.4 Country-specific trends in the estimated number of people who developed MDR/RR-TB (incident cases), 30 high MDR/RR-TB burden countries, 2015–2022

The countries with the largest share of the global number of people estimated to have developed MDR/RR-TB (incident cases) in 2022 were India (27% of global cases), the Philippines (7.5% of global cases) and the Russian Federation (7.5% of global cases) (Fig. 1.3.5).

Fig. 1.3.5 Estimated number of people who developed MDR/RR-TB (incident cases) in 2022, for countries with at least 1000 incident cases^a

The proportion of people with TB who had MDR/RR-TB varies considerably among regions and countries (Fig. 1.3.6, Fig. 1.3.7). For people with no previous history of TB treatment (new cases), best estimates range from less than 3% in the WHO African, South-East Asia and Eastern Mediterranean regions to 24% in the European Region. For people previously treated for TB, best estimates range from 8.4% in the Eastern Mediterranean Region to 54% in the European Region. At country level, the highest proportions are found in the Russian Federation and in several countries in eastern Europe and Central Asia.