ReacciónIf an individual with diabetes is found to have a positive TB screening result, they should receive a confirmatory diagnostic test as soon as possible. Studies suggest an association between diabetes and MDR-TB (109), and, given the increased risk of mortality in this population, it is critical that the correct TB treatment regimen be provided as early as possible once TB is diagnosed. Therefore, drug susceptibility testing is also important, in addition to establishing the diagnosis of TB disease.
3.2.1 How to diagnose TB
The WHO standard: universal access to rapid tuberculosis diagnostics (110) includes two benchmarks that require: a) all individuals have access to an mWRD as an initial diagnostic test and b) all facilities use an algorithm that includes an mWRD as an initial diagnostic test.
Sputum-smear microscopy, which has been the traditional method of diagnosing TB, has low sensitivity and cannot distinguish drug-susceptible from drug-resistant bacilli. MWRDs were first approved for diagnosing TB and detecting rifampicin-resistant TB (RR-TB) in 2011. The evidence shows that these tests are cost-effective, are more accurate than microscopy and reduce the time to diagnosis, with a resulting impact on patient-important outcomes such as mortality. WHO therefore recommends that TB programmes replace microscopy as the initial diagnostic test with mWRDs that detect M. tuberculosis complex bacteria. Microscopy should, however, be retained for monitoring clinical responses to TB treatment.
3.2.2 Linkage to TB diagnostic networks
Prompt diagnosis and initiation of treatment are critical components of basic TB care. Services should be people-centred and should take into account convenience, harmonization of clinic appointments and out-of-pocket costs for people seeking care. Locating services for diabetes care and TB diagnosis in the same health facility or health campus facilitates referral of people with diabetes for investigations for TB as required. Where TB diagnostic services are not yet available within the same facility, provision should be made for timely sample transport for TB investigations and transmission of results. WHO and the Global Laboratory Initiative (GLI) have published best practices for TB laboratory strengthening to guide assessment of the diagnostic network and to identify opportunities to improve access to TB diagnostic services for people attending diabetes care (111). The GLI handbook: Laboratory diagnosis of tuberculosis by sputum microscopy: the handbook. Global edition (112), provides further practical guidance relating to sputum transportation.
To improve client follow-up, recording and reporting tools should be updated and diagnostics connectivity solutions used to automate reporting for both TB and the diabetes service providers. SOPs for periodic review and reporting should be updated to ensure the involvement of relevant staff in monitoring implementation of TB and diabetes activities. Further details of monitoring and evaluation for NTPs and NCD programmes are discussed in Chapter 2.
3.2.3 Sample collection and transportation for TB diagnosis
Collection of an appropriate sample is a key step in the diagnosis of TB. Capacity-building in sputum collection and packaging for transport should be prioritized when planning to link facilities offering diabetes care to TB diagnostic services through a sample transportation network. SOPs should be developed to ensure specimens of good quality to ensure the accuracy and reliability of the test results. Commodities such as appropriate specimen containers and transport packaging should be available.
Collection of sputum may be a significant hazard, as coughing produces potentially infectious aerosols. Measures should therefore be taken to minimize exposure of other people to these aerosols and to identify a suitable location for sputum collection (25,113). When possible, sputum specimens should be collected in a dedicated room or an area outdoors where infectious droplets will be rapidly diluted and ultraviolet light can rapidly inactivate TB bacilli. Guidance on safe collection of good-quality sputum specimens and sputum transportation is provided in Laboratory diagnosis of tuberculosis by sputum microscopy: the handbook. Global edition (112).
3.2.4 Household contact investigation
Once TB is diagnosed, treatment should be started as soon as possible, and household contacts of the individual should be screened for TB and assessed for eligibility for TPT. Household contacts may also have undiagnosed diabetes. Therefore, combining TB screening with assessment for risk of diabetes in households further extends access to TB and diabetes care and prevention (114). Further guidance on screening of household contacts is given in the WHO operational handbook on TPT (115).
