Operational Handbooks

A successful screening programme may lead to a diminishing yield over time, at least if the risk group is a fixed population. Over time, changes in the background burden of TB and changes in the profile of TB patients in the community (for example, a trend towards fewer patients with symptomatic TB, fewer cases of sputum smear-positive TB and decreasing TB mortality) can lead to a reduction in the yield from screening, an increase in the NNS, a reduction in cost–effectiveness and a change in the ratio of benefits to harm.

Depending on the objectives of the screening programme and the results of monitoring the indicators discussed above, a special assessment may be necessary to determine, for example, the reasons for low uptake of screening, an unexpectedly low proportion of people presumed to have TB identified by screening, a low proportion of those presumed to have TB who were further evaluated for TB, a higher-than-expected NNS or a high proportion of cases that are not bacteriologically confirmed.

Monitoring and evaluating systematic screening should be incorporated into the monitoring and evaluation programmes used in the national TB programme. The programme will determine the roles of the people involved in monitoring and its characteristics (e.g. frequency of monitoring, methods used, how the information collected will be fed back to adjust screening). Targets should be set for the expected caseload and yield, the NNS and costs in relation to benefits. Targets should be based on the estimated under-detection in different settings but should also account for programme realities.

A monitoring and evaluation plan should be part of any screening programme. General conditions and risk group-specific conditions for discontinuing screening should be established from the outset – for example, in relation to yield, contribution to overall case detection and improvement in treatment enrolment and outcomes, cost per case detected or some combination of these. Indicators should be chosen, and digital forms created for collecting data or adapted to the specific objectives and local conditions.

It is critical to pilot-test a newly designed screening programme to ensure that it is operational. Pilottesting is a valuable opportunity to refine new instruments (e.g. digital radiography, CAD and CRP), protocols, data systems and management structures. It also allows initial evaluation of the performance of the screening programme in terms of yield and costs to ensure that it has the intended effects on case detection, so that the design or the protocol can be modified if necessary.

The goal of resource mobilization is to support the start-up, pilot-testing and maintenance of TB screening. In the initial phases, national TB programmes may not have allocated funding for new screening activities, and funds might have to be sought from alternative domestic and external sources (14). Usually, once screening activities become routine and are shown to be effective, funding becomes available from mainstream domestic and external TB programme budgets.

Many different stakeholders and partners may be involved in screening for TB. It is important to involve communities and the target population when planning activities to ensure that the screening activities are feasible and acceptable. These stakeholders may also be able to plan mobilization and sensitization to inform the target population and motivate them to be screened. The programmes, services and stakeholders identified for collaboration in screening (see 2.2.1) should collaborate in the planning of screening.

Ethical issues should be considered from the onset of planning and should involve end-users. The design of screening interventions for specific risk groups should involve risk groups and organizations that might work with these populations, especially groups that face specific access barriers or discrimination. This should help in arriving at user-friendly, acceptable, effective approaches and building demand for services and their use.

Consideration should be given to the extra resources, both human and financial, that will be necessary to prepare for, carry out and monitor screening activities and to accommodate the increased demand for testing of people with presumptive TB and the extra patients who may be identified by screening.

Screening algorithms combine one or several screening tests and one or several diagnostic tests. The accuracy of different screening tests and potential algorithms for different populations and the considerations to be made when selecting algorithms, are discussed in detail in Chapter 3.