Test more people to reduce new TB deaths, study finds

Words: Marcus Low / GroundUp

---

Many people who report TB symptoms at South Africa’s public sector clinics do not receive TB tests. Testing more of these people is one of the most effective things we can do to reduce rates of TB disease and death, according to a major new modelling study.

While South Africa has made substantial progress against tuberculosis (TB), we are not on track to meet key targets set for 2030. This is according to a new modelling paper published in the journal Global Health Action.

New TB cases in South Africa were projected to decline by 46% by 2030, relative to a 2015 baseline. The World Health Organisation (WHO) End TB target adopted by South Africa aimed at an 80% reduction in new cases.

TB deaths were projected to decline by 54%, against the End TB target of 90%.

The researchers also estimated the uncertainty of their projections. These are called uncertainty intervals. Even though these intervals are relatively wide, their upper limits are below the End TB targets, suggesting that it is unlikely that South Africa will reach the targets by 2030. The modelling however also identified interventions that could help South Africa get closer to the targets.

The new research is an extension of Thembisa, an existing mathematical model of HIV and TB in South Africa. University of Cape Town epidemiologist Dr Leigh Johnson, who is the lead author of the new study, is also the main developer of Thembisa.

Identifying what works

The researchers estimated which of a long list of interventions would have the greatest impact against TB.

They found that the greatest reductions in TB would be achieved if a high percentage (89%) of people reporting with TB symptoms were tested using new TB tests at clinics (known as point-of-care tests).

This would result in a 49% reduction in new TB cases over time and a 67% reduction in TB deaths, compared to a scenario in which there are no changes to current programmes.

The World Health Organisation earlier this year recommended the use of these new point-of-care TB tests. These tests aren’t yet in general use in South Africa, although they are being evaluated in pilot projects.

The new tests can be run on both sputum and tongue swabs. For now, most TB tests in South Africa still involve someone producing a sputum sample, something some people struggle with, and the sample being transported to a lab for testing.

The researchers also found that high rates of door-to-door testing with the new point-of-care tests could reduce new TB cases and deaths by 38% and 49% respectively, while combining high rates of door-to-door testing and digital chest X-ray screening in asymptomatic individuals could reduce new TB cases by 17% and deaths by 21%.

Even without the new tests, there are substantial gains to be had if testing was stepped up in people with symptoms. New TB cases could be reduced by as much as 29% if the level of sputum testing in people seeking care for TB symptoms were increased.

Once people have been diagnosed with TB and start taking TB treatment, they typically become non-infectious within about two weeks. Diagnosing people more quickly results in people remaining infectious for shorter periods, slowing TB transmission.

Other influential parameters identified by the researchers include the extent to which covid-related behaviour changes are sustained, the rate at which people living with HIV start taking antiretroviral treatment (untreated HIV is a major driver of TB), and the combined uptake and efficacy of 3HP, a relatively new form of TB preventive therapy.

Testing is key

‘We found that the rate of testing in people seeking treatment for TB symptoms is the most important driver of future TB incidence [new cases] and mortality [deaths],’ wrote the authors.

‘This finding is not surprising given the historically low rates of TB testing. In studies of patients seeking treatment for TB symptoms in South African health facilities, the proportion who received a TB test has been highly variable, ranging from 3% to 84%, with a median of only 30%. Similarly low rates have been reported in other countries with high TB burdens.’

The authors explain: ‘Achieving high levels of testing in people with TB symptoms could require levels of laboratory testing beyond current testing capacity. However, new point-of-care tests performed on tongue swabs or sputum present an important opportunity to increase levels of TB testing in symptomatic individuals at reduced cost, without placing additional strain on laboratories.’

Besides reduced cost, the new point-of-care tests also offer quicker test results and have lower operational requirements. The main potential benefit of these tests over existing lab tests is that they are likely to be used much more frequently.

The authors also argue that there is a need to strengthen adherence to guidelines for systematic testing of all patients with symptoms suggestive of TB and that we need a larger healthcare workforce dedicated to TB diagnosis, better supply chains, and better monitoring systems to identify where and why symptomatic patients are not being tested.

This is a shortened, edited version of an article published by Spotlight.

Note: The study reported on here was supported by the Gates Foundation. Spotlight receives funding from the Gates Foundation, but is editorially independent, an independence that the editors guard jealously.

---

Be the first to know – Join our WhatsApp Channel for content worth tapping into! Click here to join!

---

Also read:

Spring pet care tips: Seasonal allergies & health risks

Picture/Illustration: Lisa Nelson / GroundUp

The post Test more people to reduce new TB deaths, study finds appeared first on Cape Town ETC.