The role of DOTS in tuberculosis treatment and control.

Directly Observed Therapy Shortcourse (DOTS) is composed of five distinct elements: political commitment; microscopy services; drug supplies; surveillance and monitoring systems and use of highly efficacious regimens; and direct observation of treatment. The difference in the way the term 'DOTS' as defined by WHO and interpreted by many observers has led to some misunderstanding. WHO generally uses the term to mean the five components of DOTS. But the word 'DOTS' is an acronym for Directly Observed Therapy Shortcourse. Many workers therefore interpret DOTS purely as direct supervision of therapy. DOTS is not an end in itself but a means to an end. In fact it has two purposes, to ensure that the patient with tuberculosis (TB) completes therapy to cure and to prevent drug resistance from developing in the community. The main criticism of DOTS rightly derives from the fact that some properly conducted randomized, controlled trials of directly observed therapy with or without the other components have shown no benefit from it. The problem is that it is impossible to design a study of modern directly observed therapy against the previous self-administered, poorly-resourced programs. As soon as a study is implemented, the attention to patients in the control (non-directly observed therapy) arm inevitably improves from the previous non-trial service situation. What is of concern is that in some trials less than 70% cure rates were achieved even in the direct observation arm. With no new drugs or adjuvant treatment available to bring the length of treatment down to substantially less than 6 months, DOTS offers the best means we have at our disposal for TB control.