Well-designed trials and rigorous quasi-experimental studies in different settings are required to investigate the effects of population-wide systematic screening for TB on individual-level outcomes (diagnostic delay, treatment outcomes, costs to patients, social consequences) and populationlevel outcomes (TB prevalence, incidence, transmission), as well as to guide implementation choices (including the method of delivery, screening algorithms, the duration of screening intervals and frequency of screening, and the mode of delivering the intervention).
Research on the longer-term impacts of screening, including any potential evidence of averted morbidity or mortality, is not necessarily captured in the existing data. Research on the cost– effectiveness of screening is needed, using a longer time horizon to adequately capture all potential costs and longer-term effects, including potential reduced future prevalence and incidence.
Observational research and programmatic evaluations reporting the impact of community-wide screening on TB case notification rates – which provide an important source of evidence on the impacts of screening under programmatic conditions – must be carefully designed and analysed to minimize bias.
Studies of screening interventions should incorporate both qualitative and quantitative assessment of the indirect effects of screening, given the importance of health-seeking behaviour in TB care engagement and the potential impact of population-wide screening to change it and the importance of assessing any unintended mental, social or economic consequences of screening (including adverse effects, the burden of the test and downstream outcomes of clinical management that is guided by the outcomes of test results).