Xpert MTB/RIF testing has reduced MDR-TB treatment delays in South Africa

Although the introduction of the Xpert MTB/RIF test for TB and drug-resistant TB has improved the time from clinic presentation to second-line treatment in South Africa since 2011, improved access to treatment and a reduction in delays of treatment initiation are still required in many settings, according to a retrospective analysis presented by Dr Helen Cox of the University of Cape Town at the 46th Union World Conference on Lung Health in Cape Town from 2 to 6 December 2015.

Xpert MTB/RIF is a rapid test for identification of TB and rifampicin resistance. The test is being rolled out as a newer diagnostic for TB management in countries with a high burden of TB and HIV co-infection, but there is limited evidence on the impact of the test in improving access to care.

Reducing the time between identification of symptoms that suggest TB and the start of treatment is critically important. A long delay between seeking health care and starting treatment increases the risk of death from TB. People with TB may be lost from care and in the meantime pass on TB to their close contacts.

Glossary

second-line treatment

The second preferred therapy for a particular condition, used after first-line treatment fails or if a person cannot tolerate first-line drugs.

inter-quartile range

The spread of values, from the smallest to the largest. The inter-quartile range (IQR) only includes the middle 50% of values and measures the degree of spread of the most common values.

capacity

In discussions of consent for medical treatment, the ability of a person to make a decision for themselves and understand its implications. Young children, people who are unconscious and some people with mental health problems may lack capacity.

retrospective study

A type of longitudinal study in which information is collected on what has previously happened to people - for example, by reviewing their medical notes or by interviewing them about past events. 

polymerase chain reaction (PCR)

A method of amplifying fragments of genetic material so that they can be detected. Some viral load tests are based on this method.

South Africa has rolled out the most Xpert MTB/RIF tests in the world, but the impact of this expansion in diagnostic capacity is still being examined. The study presented at the Union World Conference on Lung Health examined how long it takes patients to start second-line treatment and how the roll-out of the Xpert MTB/RIF test has reduced treatment delays over time.

The study compared cohorts of patients before and after the introduction of Xpert MTB/RIF testing. Laboratory records of rifampicin-resistant TB diagnosis were analysed in a 2011 pre-Xpert MTB/RIF testing cohort made up of approximately 300 cases from each of the nine provinces. The 2013 cohort (after Xpert MTB/RIF was introduced) was also made up of approximately 300 cases from each of the nine provinces.

These were retrospectively followed up between January 2014 and March 2015 using TB registers, National Health Laboratory Services (NHLS) records and medical records in diagnostic and treatment facilities to determine the second-line treatment start. All cases with a previous rifampicin-resistant TB diagnosis in the last six months and those already on treatment were excluded from the analysis.

The study found that the median time to treatment was 61 days in 2011 compared to 28 days in 2013. In 2011, only 7% of diagnosed cases had initiated treatment within five days, as per the national target, compared to 13% in 2013, after Xpert MTB/RIF had been introduced. Forty per cent in 2013, compared to 18% in 2011, had initiated treatment within one month of diagnosis and 64% in 2011, compared to 52% in 2013, had started treatment within six months. 

Of the 2624 cases in the pre-Xpert MTB/RIF 2011 cohort, 2411 (92%) were new rifampicin-resistant cases, 111 (4%) had a previous rifampicin-resistance diagnosis but had not received second-line treatment and 102 (4%) had a previous rifampicin-resistance diagnosis and had received second-line treatment.

Of the 2688 cases in the post-Xpert MTB/RIF 2013 cohort, 2426 (90%) were new rifampicin-resistant cases, 119 (4%) had a previous rifampicin-resistance diagnosis but had not received second-line treatment and 143 (5%) had a previous rifampicin-resistance diagnosis and had received second-line treatment.

A further analysis of the means of rifampicin-resistance diagnosis of the 2013 cohort showed that 57% (n = 1379) were diagnosed using Xpert MTB/RIF compared to 43% (n = 1041) who were diagnosed using other laboratory methods such as PCR and culture. The median laboratory time for the Xpert MTB/RIF was one day (IQR: 0-2) compared to 35 days (IQR: 18-52) in those who were diagnosed without using Xpert MTB/RIF. The median time to treatment was 19 days (IQR: 3-36) for the cases diagnosed using Xpert MTB/RIF compared to 47 days (IQR: 13-81) in the other group.

According to the study, 68% of diagnosed cases in the 2013 cohort had received treatment at any point, compared to 62% in 2011. Although this shows a significant treatment gap, it is less than that reported using routine data.

References

Cox H et al. The drug-resistant TB treatment gap and treatment initiation delays in South Africa: impact of Xpert implementation. OA: 390-05. 46th Union World Conference on Lung Health, Cape Town, 2015