Ongoing challenges to understanding multidrug and rifampicin-resistant tuberculosis in children versus adults.

Previous analyses suggest children with tuberculosis (TB) are no more or no less likely to have multidrug- or rifampicin-resistant TB (MDR/RR-TB) than adults. However, the availability of new data, particularly for high MDR/RR-TB burden countries, suggest updates of country-specific estimates are warranted.We used data from population-representative surveys and surveillance collected between 2000 and 2018 to compare the odds ratio (OR) of MDR/RR-TB among children (<15 years) with TB, compared to the odds of MDR/RR-TB among adults (≥15 years) with TB.In most settings (45/55 countries), and globally as a whole, there is no evidence that age is associated with odds of MDR/RR-TB. However, in some settings such as former Soviet Union countries in general, and Georgia, Kazakhstan, Lithuania, Tajikistan and Uzbekistan in particular, as well as Peru, MDR/RR-TB is positively associated with age ≥15. Meanwhile, in Western Europe in general, and the UK, Poland, Finland and Luxembourg in particular, MDR/RR-TB is positively associated with age <15. Sixteen countries had sufficient data to compare over time between 2000-2011 and 2012-2018, with evidence for decreases in the OR in children compared to adults in Germany, Kazakhstan and the USA.Our results support findings that in most settings a child with TB is as likely as an adult with TB to have MDR/RR-TB. However, setting-specific heterogeneity requires further investigation. Further, the OR for MDR/RR-TB in children compared to adults is generally either stable or decreasing. There are important gaps in detection, recording and reporting of drug resistance among paediatric TB cases, limiting our understanding of transmission risks and measures needed to combat the global TB epidemic.