Some of the most exciting results presented at the
conference on active case finding concerned the impact of implementing the
Xpert MTB/RIF test in South Africa and Kenya.
Professor Harry Hausler of the TB/HIV Care Association
reported on TB REACH-funded case finding in the Sisonke district of
Kwazulu-Natal province, South Africa. The district in which the project is
taking place was the first in South Africa to use Xpert MTB/RIF to test all people with suspected TB.10
“Xpert has really facilitated case finding in this deeply
rural district of Kwazulu-Natal,” said Professor Hausler.
Five sub-district labs are equipped to run the test, and
mobile teams routinely screen for TB symptoms and collect sputa for testing at
these labs. The results are then communicated to clinics and community health
workers, who are responsible for recalling patients with a positive Xpert
MTB/RIF result, as well as organising the screening of contacts. There are
approximately 800 community health workers in Sisonke district.
Between October 2011 and October 2012, 21,712 tests were
carried out, diagnosing 1471 TB cases, 9.9% of which were rifampicin-resistant.
Smear testing is carried out at baseline in order to monitor treatment;
one-third of all these cases were smear-negative. 93% of the TB cases had a
recorded HIV test result, and 72.4% of these patients were HIV-positive.
During 2012 active case finding almost doubled the number of
samples referred for Xpert MTB/RIF testing compared to the last quarter of 2011,
while the proportion of TB cases detected among those tested fell from 12 to 4% in the last quarter.
Although mobile health teams play an important role in the
drive to improve active case finding, Prof. Hausler noted that the vast
majority of TB cases continue to be identified through passive case finding
within health facilities (91%), and that door-to-door case finding produces a
very low yield of TB cases. Just 1% of those referred for Xpert MTB/RIF testing
as a result of door-to-door case finding were found to have active TB, compared
with 9% of presumptive TB cases referred for testing within health facilities.
One of the most important reasons for implementing Gene
Xpert testing is because it has the potential to reduce the delay between
identification of a presumptive TB case, delivery of a positive result and the
initiation of TB treatment. The longer that treatment is delayed the greater
the risk of death and transmission of TB to others. In a sample of patients
referred for testing between January and June 2012, Prof. Hausler showed that
40% of those diagnosed with active TB started TB treatment within 48 hours of
providing a sputum sample, and 27% within two to five days.
“We are hoping that this is going to translate into reduced
TB transmission in the community,” said Dr Hausler. “What’s even more exciting
is that around 40% of drug-resistant TB patients are started on an MDR regimen
within 48 hours.” At one site, Pholela community health clinic, Prof. Hausler
showed that TB treatment initiation within five days of giving sputum had risen
from 10% of patients in the April to June 2011 period to 89% of patients in the
same quarter in 2012, and 61% of patients diagnosed with active TB at that
clinic started TB treatment less than 24 hours after giving their sputum
sample, an impressive vindication of the argument that Xpert MTB/RIF scale up
has the potential to dramatically limit the time during which people can transmit
TB to others.
This rapid turnaround is underpinned by the involvement of
Community Health Facilitators, lay people who form the link between the labs
and the clinics. They are responsible for checking Xpert results on a daily
basis and passing that information back to the clinics as quickly as possible.
Community health workers are then tasked with getting people diagnosed with TB
onto treatment as quickly as possible by following them up in the community.
Anyone who tests HIV-positive will also be initiated onto ART as quickly as
In cases where TB is suspected but microscopy yields a
smear-negative result, the delay to treatment that results from referral for
culture means that patients will continue to deteriorate. Smear-negative TB is more
likely to be diagnosed in people living with HIV, who will also be in need of
antiretroviral therapy if they are found to have TB. Xpert MTB/RIF has the
potential to greatly reduce the delay before treatment initiation in
Dr Jane Carter, the TB/HIV technical advisor for USAID
AMPATH presented on the results of using the Xpert MTB/RIF on smear-negative
patients in an existing TB REACH programme at 200 primary health care
facilities in the north west of Kenya.11
“We found that the Gene Xpert can be rolled out swiftly and
effectively to peripheral health units to aid in TB diagnosis,” said Dr Carter.
Five thousand patients with smear-negative TB are to be
offered culture diagnosis as part of the project. The culture laboratory is
centralised in Eldoret, which is six to eight hours drive from some of the
sites. Xpert MTB/RIF testing is to be offered to 2000 smear-negative TB
patients. Gene Xpert facilities were established at three peripheral sites in
three sub-districts, with the aim of bringing diagnostic services closer to
patients. A hub transport system was established to transport specimens,
request forms and result forms to and from the health facilities to the testing
sites which were between two and 26km apart.
If a patient had a smear negative result, the same sputum
specimen would be used for both the culture and Xpert MTB/RIF test. This was to
avoid the inconvenience and cost to the patient of needing to return to the
facility to provide a second sample. Although TB care and diagnostic tests are
free in Kenya, patients are charged a minimum of KSh100 (equal to one day’s
wage) to register at the health facility.
Of the 1171 culture tests performed on non-contaminated
specimens between December 2011 and July 2012, 9.4 % (n=99) were found to be
culture positive. The culture arm had to be stopped prematurely due to poor
supply chain management which did not allow for reliable supply of the culture
reagent, leading all smear-negative samples to receive Xpert MTB/RIF testing.
The Xpert MTB/RIF test found a similar positivity rate for
drug-resistant (DR)TB. Of the 824 smear-negative patients screened using Xpert
MTB/RIF between December 2011 and September 2012, 8.6 % (n=71) were found to
have TB, while two cases of rifampicin resistant TB were found.
One of the main advantages of using Xpert MTB/RIF over the
culture testing was that the time it took for the clinician to receive results
after sending the sputum sample decreased from five weeks to five days.