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Stepping up tuberculosis preventive therapy for household contacts

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A substantial proportion of adults who are diagnosed with pulmonary tuberculosis (TB) and who successfully complete anti-TB treatment are left with impaired lung function, which increases their chance of morbidity and mortality compared with the general population.  Assessing these people at the end of anti-TB treatment within the programmatic setting is an area of interest for the Centre for Operational Research at The Union. Work is on-going in China and work is about to start through a SORT IT (Structured Operational Research and Training Initiative) Programme in Kenya, Uganda, Zambia and Zimbabwe this month (March 2023).

A recent study by Leonardo Martinez and colleagues published in the American Journal of Respiratory and Critical Care Medicine demonstrates similar problems in young children. In a prospective birth cohort of children in South Africa followed through to five years of age, those diagnosed with TB had subsequent impaired growth, a higher frequency of wheezing and impaired lung function compared with those who did not have TB.

The increasing evidence base on post-TB disability in adults and children highlights the growing need and importance of TB preventive therapy (TPT) for those at high risk of the disease. Amongst these high-risk groups are household contacts of the first people in the population with TB (known as index patients), particularly household contacts aged under five years.

At the United Nations High Level Meeting (UNHLM) in 2018, targets were set to put four million household contacts aged under five years and 20 million household contacts aged 5 years and over on TPT between 2018 and 2022. In this regard, the latest WHO Global TB Report 2022 makes woeful reading, with 40% of household contacts aged under 5 years and just 3% of those aged 5 years and over put on TPT between 2018 and 2021. Furthermore, unpublished work from a pilot TPT implementation project in India through The Union South East Asia office suggests that household contact screening and initiation of TPT for those eligible for these interventions can take up to two months and beyond. Such delays effectively negate the value of these interventions in breaking household transmission.

The Centre for Operational Research, with funding support from Resolve to Save Lives, is seeking to address these challenges, and in India, Pakistan and Kenya is implementing a “7-1-7” metric for household contact tracing in index patients with bacteriologically confirmed pulmonary TB. The metric indicates that: the household contacts should be line listed within “7” days of the index patient being registered; the line-listed household contacts should be symptom screened within the next “1” day: and the screened household contacts should be started on TPT, anti-TB treatment or no drugs (because they are not eligible) within the next “7” days.

Preliminary results from Chennai, India, show that before implementation of “7-1-7” (historical controls), 62 (16%) of 381 household contacts of index patients with TB were started on TPT over a three-month period. With implementation of “7-1-7”, 67 (35%) of 192 household contacts of index patients have been started on TPT, a nearly two-fold increase. Of those who started on TPT, six were children under five years of age. Line listing of household contacts within “7” days was done in 89%; symptom screening within “1” day in 46% and TPT, anti-TB treatment or no drugs started within the next “7” days in 72% of the household contacts.

These are early but encouraging results. The work continues and full results from India, Pakistan and Kenya will be analysed, interpreted and published later in the year.