Methodological issues in the design of clinical trials for the treatment of multidrug-resistant tuberculosis: challenges and opportunities.

The burden of multidrug-resistant tuberculosis (MDR-TB) is increasing dramatically in the world today, severely hampering global TB control. Treatment of MDR-TB is complex, prolonged, expensive and requires appropriate clinical and laboratory infrastructure. The majority of MDR-TB patients still do not have access to adequate diagnostic services or quality assured second-line drugs, leading to high levels of morbidity and mortality. More effective and efficient MDR-TB treatment with reduced toxicity that could be safely delivered to patients co-infected with human immunodeficiency virus (HIV) is an urgent research priority that could be cost-saving for health systems overall. In this context, understanding how best to design and execute randomised controlled trials to improve MDR-TB treatment has taken on new urgency, to identify the optimal combination(s) of existing and new drugs to assemble in efficient and safe regimen(s), preferably of short duration, that can be easily delivered to patients and safely combined with antiretroviral treatment. In the present report, we address the methodological issues in the design and execution of Phase II and Phase III trials arising from this goal. We suggest that a rational selection of appropriate designs and outcome measures, associated with the application of new diagnostic technology, could overcome many of the methodological and logistical problems. These advances could be key to historic improvements in the treatment of patients suffering from MDR-TB, and perhaps ultimately drug-susceptible TB. As with HIV, clinical trials in patients with drug-resistant disease may provide a quicker and less expensive path to licensure than trials for treatment of drug-susceptible disease.