More Evidence and Better Diagnostics Needed Before Redefining Severe Forms of Drug-Resistant TB

23 MARCH 2012 | GENEVA – Reports of tuberculosis (TB) cases with severe patterns of drug resistance are increasing, said experts who attended a WHO meeting in Geneva on 21-22 March. Participants stressed that the emergence of drug resistance should be a wake-up call for Ministries of Health. The group urged the global TB community to make greater efforts to prevent drug resistance and scale up provision of appropriate care and management to avoid a scenario where TB becomes incurable.

Insufficient evidence

The meeting concluded that there is currently insufficient evidence to adopt new case definitions for drug-resistant TB. Drug susceptibility testing (DST), which is key to defining new levels of drug resistance, lacks accuracy for several of the drugs that are used to treat multi drug-resistant (MDR) and extensively drug resistant (XDR)-TB. Secondly, there is insufficient correlation of DST results with clinical response to treatment for several drugs currently used to treat XDR-TB. Thirdly, new drugs are currently undergoing clinical trials, and could prove effective against drug resistant strains. The meeting urged diagnostics companies and TB laboratories to develop better diagnostic tests and also agreed that WHO and technical partners should develop more detailed guidance on XDR-TB treatment.