Using the PICO (population, intervention, comparator and outcome) format, the WHO Steering Group drafted the initial questions. These questions were used to guide the systematic reviews and to assess the evidence to inform the development of the updated guideline document. The initial PICO questions were then revised based on feedback from the Guideline Development Group. The final PICO questions are listed below. Additionally, to provide targeted recommendations to specific groups based on the likelihood of acquiring TB infection or developing active TB disease, a set of background questions were drafted to inform the PICO questions. These background questions focused on evaluating:
- the level of risk of acquiring M. tuberculosis infection or developing active TB disease among health workers (including community care workers) in various clinical settings (Background question 1);
- the level of risk of acquiring M. tuberculosis infection or developing active TB disease among individuals living in TB-affected households or spending time in congregate settings (Background question 2); and
- (the status of) infectiousness of TB patients after having been started on effective treatment (Background question 3).