INT J TUBERC LUNG DIS 19(4):392–398
Q 2015 The Union
http://dx.doi.org/10.5588/ijtld.14.0653
The impact of XpertW MTB/RIF in sparsely populated rural
settings
T. Van Den Handel,* K. H. Hampton,† I. Sanne,*‡ W. Stevens,§¶ R. Crous,# A. Van Rie†
*Right to Care, Johannesburg, South Africa; †Department of Epidemiology, University of North Carolina Gillings
School of Global Public Health, Chapel Hill, North Carolina, USA; ‡Clinical HIV Research Unit, Department of
Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, §Department of Molecular
Medicine and Hematology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, ¶National
Health Laboratory Services, Johannesburg, #Rural Districts, Western Cape Department of Health, Cape Town,
South Africa
SUMMARY
Xpertw
The impact of implementing
MTB/RIF and the choice of instrument placement on
patient care in sparsely populated areas with poor access
to laboratory and radiology services have not yet been
elucidated.
M E T H O D S : Prospective evaluation of three diagnostic
approaches in the Central Karoo, South Africa: smear
microscopy as the initial diagnostic, with sputum
processing at centralised laboratories, and Xpert as the
initial diagnostic with instrument placement at facility
level or centralised laboratory.
R E S U LT S : Of 1449 individuals, 196 were diagnosed
with TB. The proportion positive on initial testing was
respectively 8%, 20% and 8% during the smear
microscopy, decentralised Xpert and centralised Xpert
periods. The proportion of bacteriologically confirmed
cases was respectively 88%, 99% and 91% during the
smear microscopy, decentralised Xpert and centralised
Xpert periods. The median time to treatment was
respectively 11.5 (interquartile range [IQR] 6–24), 1
(IQR 0–2) and 6 days (IQR 2–9) during the smear
microscopy, decentralised Xpert and centralised Xpert
periods.
C O N C L U S I O N : Introducing Xpert as the initial diagnostic in areas with poor access to TB diagnostics
increased the proportion of cases with bacteriological
confirmation and reduced time to treatment initiation;
however, point-of-care placement may have resulted in
fewer people being evaluated for TB.
K E Y W O R D S : impact; Xpert MTB/RIF; rural
TO REDUCE TUBERCULOSIS (TB) morbidity and
mortality and limit onward transmission of Mycobacterium tuberculosis, TB control programmes aim
for early detection of all cases, identification of drug
resistance and timely initiation of appropriate treatment.1,2 A promising tool in the fight against TB is the
Xpertw MTB/RIF (Cepheid, Sunnyvale, CA, USA)
assay using the GeneXpert instrument, an automated
diagnostic system that can rapidly detect M. tuberculosis and rifampicin (RMP) resistance with high
sensitivity and specificity in sputum samples.3,4 As
the system does not require specialised operator skills
or bio-containment infrastructure, Xpert can be used
at certain lower level health care facilities.5–7
The World Health Organization has endorsed
Xpert as the initial diagnostic for TB in people
suspected of having multidrug-resistant (MDR-) and
human immunodeficiency virus (HIV) associated TB.
In 2011, South Africa initiated national phased
implementation of Xpert for all individuals with
presumptive TB. To facilitate rapid implementation
and increase cost efficiency, the South African
Department of Health (Pretoria, South Africa)
decided to place all Xpert instruments at existing
microscopy laboratory centres.8
While Xpert implementation has been shown to
reduce the time to treatment initiation in urban
settings,9–11 few data exist on the impact of Xpert in
rural areas where people have less access to health
care or laboratory facilities and are thus at higher risk
of prolonged delay in diagnosis and treatment.1
We aimed to determine the impact of Xpert
implementation on the time to anti-tuberculosis
treatment initiation and the proportion of TB cases
that were bacteriologically confirmed in a sparsely
populated rural area in South Africa with poor access
to diagnostic services and a prevalence of MDR-TB
BACKGROUND:
Correspondence to: Theo Van Den Handel, Right to Care, Western Cape, P O Box 54 Plettenberg Bay, Western Cape 6600,
South Africa. Tel: (þ27) 44 533 3067. Fax: (þ27) 44 533 3286. e-mail: [email protected]; vdhandel@iafrica.
com
Article submitted 10 October 2014. Final version accepted 3 December 2014.
[A version in French of this article is available from the Editorial Office in Paris and from the Union website www.theunion.org]
Impact of Xpert in rural settings
393
Figure 1 A) Map of South Africa with the Central Karoo district municipality highlighted, and B)
map of Central Karoo displaying the locations of health care and laboratory facilities. POC ¼ point
of care.
and HIV-associated TB that would be considered low
for South Africa, but intermediate globally.
STUDY POPULATION AND METHODS
Setting
The Central Karoo District (Karoo) of the Western
Cape Province in South Africa is a rural, sparsely
populated area covering 38 854 km2 — about the size
of Switzerland — with a total population of 71 011
and a population density of 1.8 inhabitants/km2,
significantly lower than the average population
density in the rest of South Africa (41.7 inhabitants/
km2).12 Almost half (48%) of the Karoo population
lives in the capital city of Beaufort West; the
remainder reside in towns with 5000–7000 inhabitants (Laingsburg, Murraysburg, Prince Albert),
small towns of 1500–3000 inhabitants (Leeu Gamka,
Nelspoort, Merweville) or small communities and
isolated farms (Figure 1, Table 1). The terrain is semidesert, and economic activity consists mostly of sheep
and game farming, with little industry.
Within the Western Cape Province, the Karoo has
the highest percentage of deaths due to TB (8.4%)
despite having the lowest HIV prevalence among TB
cases (11.4%), the highest poverty (32.5%) and
unemployment rates (30.8%), the lowest human
development index (0.60), and the lowest number
of health care facilities.12,13
Medical services are provided by 4 hospitals and 8
primary care clinics that are linked to 3 satellite
clinics, 8 mobile clinics and 1 community day centre
(Table 1, Figure 1). The only National Health Service
Laboratory (NHLS) facility for TB diagnosis is
located at the Beaufort West Hospital. All other
facilities courier samples at least once a week to an
NHLS laboratory located 60–160 km away (Table 1).
Radiology services are available daily at the Beaufort
394
The International Journal of Tuberculosis and Lung Disease
Table 1 Characteristics of the health care facilities serving the population (n ¼ 71 011) of the Central Karoo, Western Cape Province,
South Africa
Local municipality
Beaufort West
Town
Population
Health care facilities
Beaufort West
34 085
1 district hospital; 3 primary
care clinics; 2 mobile
clinics; 1 community day
centre
1 TB hospital; 1 primary
care clinic; 1 mobile clinic
1 satellite clinic; 1 mobile
clinic
1 subdistrict hospital; 1
primary care clinic; 1
mobile clinic
1 subdistrict hospital; 1
primary care clinic; 1
mobile clinic
1 satellite clinic
1 subdistrict hospital; 1
primary care clinic; 1
mobile clinic
1 primary care clinic; 1
mobile clinic
1 satellite clinic
Nelspoort
1 699
Merweville
1 592
Murraysburg*
5 069
Laingsburg
Laingsburg*
5 667
Prince Albert
Matjiesfontein*
Prince Albert*
422
7 054
Leeu Gamka*
2 717
Klaarstroom*
584
Radiology
services
(number of
days/week)
Laboratory
courier
(number of
days/week)
NHLS laboratory
facility
Distance to
laboratory
km
5
5
NHLS laboratory
,10
0
5
Beaufort West
55
0
1
Beaufort West
53
1
4
Beaufort West
160
1
3
Worcester
159
0
1
1
5
Worcester
Oudtshoorn
139
113
0
3
Beaufort West
75
0
5
Oudtshoorn
60
* Facilities included in the analysis.
NHLS ¼ National Health Service Laboratory; TB ¼ tuberculosis.
West Hospital, but only once weekly at the smaller
hospitals.
Study design
We evaluated TB diagnosis and treatment initiation at
six of the nine towns/communities in the Karoo
(Table 1) during three distinct periods. Between April
and October 2011 (the smear microscopy period), all
sputum samples were sent for smear microscopy to
the assigned NHLS laboratory. In October 2011, we
placed a single one-module Xpert instrument in a
safe, secure space at hospitals located in Laingsburg,
Murraysburg and Prince Albert (the decentralised
Xpert period), and the three nurses in charge of TB
care were trained in performing the assay. Between
November 2011 and April 2012, sputum samples
were assessed using Xpert at point of care for
individuals presenting at the hospitals in Laingsburg,
Murraysburg and Prince Albert, or were transported
to these hospitals for patients presenting at other care
facilities (Table 1). Between July and December 2013,
once all study cartridges had been used, sputum
samples were again sent to the assigned NHLS
laboratories, now for Xpert processing under the
national roll-out programme (centralised Xpert period).
Clients were screened for TB symptoms (cough 72
weeks, weight loss, night sweats) according to the
South African Department of Health guidelines.14
During the smear microscopy period, two sputum
samples were collected per patient and transported by
courier to the assigned NHLS laboratory for assess-
ment using fluorescent smear microscopy. In people
with a history of anti-tuberculosis treatment, liquid
culture and drug susceptibility testing (DST) were
also requested. When Xpert was the initial diagnostic
test, a single sputum sample was collected. If RMP
resistance was detected on Xpert, a second sputum
specimen was collected for culture and DST. During
all three study periods, individuals without bacteriological confirmation of TB were prescribed antibiotics and advised to return after completion of the
antibiotics if symptoms persisted, and were referred
for assessment using chest X-ray (CXR) if clinically
indicated. Individuals diagnosed with TB were
managed according to Department of Health guidelines.14
Data collection, definitions and analysis
Patient demographic (sex, age at first sputum
collection) and clinical information (diagnostic testing dates and results, information about anti-tuberculosis treatment and HIV status) were collected from
the TB suspect register, TB treatment register, HIV
counselling and testing register, laboratory sputum
register and Xpert instrument software output.
A presumptive TB case was defined as an individual
who presented with symptoms or signs suggestive of
TB and who provided one or more sputum samples. A
bacteriologically confirmed TB case was defined as an
individual with a positive result on smear microscopy,
culture or Xpert, independent of treatment initiation.15 A clinically diagnosed TB case was defined as
an individual who did not fulfil the criteria for
Impact of Xpert in rural settings
bacteriological confirmation but was diagnosed with
active TB by a health care worker (HCW) and
initiated a full course of anti-tuberculosis treatment.
Time to treatment initiation was defined as the time
between the date of first sputum sample collection
and the date of anti-tuberculosis treatment initiation.
We compared time to treatment and proportion of
cases with bacteriological confirmation between the
three study periods: smear microscopy, decentralised
Xpert and centralised Xpert. Data from the first
weeks after placement of Xpert at the health care
facilities were excluded to allow health care staff to
adjust to the new TB diagnostic procedures. The
length of this adjustment period differed by facility,
and was determined by the time during which a mix
of Xpert and smear microscopy was performed. The
period between June 2012 and May 2013 was
excluded due to an inconsistent supply of Xpert
cartridges, after which a permanent stock was
available at all three hospitals. Cartridge supply was
dependent on donor funding, which then came to an
end. We included the same number of clinic days for
each of the three study periods of interest: 165 days
for Laingsburg and Prince Albert and 180 days for
Murraysburg.
We used standard descriptive statistics and measured the association among variables using CochranMantel-Haenszel statistics, Pearson’s v2 test and
Fisher’s exact tests. All analyses were performed
using SAS, version 9.3 (Statistical Analysis System
Institute, Cary, NC, USA). Maps were produced with
ESRI ArcGIS v10.0 (Environmental Systems Research Institute, Redlands, CA, USA).
Ethics approval
Ethics approval was obtained from the University of
the Witwatersrand Human Research Ethics Committee (HREC number: M110369), and the Institutional
Review Board of the University of North Carolina at
Chapel Hill, NC, USA. The requirement for written
informed consent was waived. Study approval was
also sought from the District and Provincial management, hospital directors and HIV/acquired immunedeficiency syndrome/sexually transmitted infection/
TB coordinators.
RESULTS
Assessment of individuals with presumptive TB
A total of 1449 individuals were assessed for TB over
1530 observation days, i.e., 510 observation days in
each of the smear microscopy, decentralised Xpert
and centralised Xpert periods, corresponding to 0.95
individuals per day in all facilities combined. Of the
1449 people assessed for TB, 584 (40%) were
assessed during the smear microscopy period, 375
(26%) during the decentralised Xpert period, and 490
(34%) during the centralised Xpert period (Table 2).
395
During all three periods, just over half (53–54%)
were male and .90% were adults (age .15 years).
Tuberculosis case finding
The proportion of positive tests among all initial tests
(microscopy or Xpert) was 8% during the smear
microscopy period, 20% during the decentralised
Xpert period and 8% during the centralised Xpert
period (Table 2).
A total of 198 cases of TB were diagnosed: 75
during the smear microscopy period, 78 during the
decentralised Xpert period and 45 during the
centralised Xpert period. During the smear microscopy period, 88% (66/75) of cases were bacteriologically confirmed: most (48/66, 73%) using smear
microscopy and some (18/66, 27%) using culture.
Others were diagnosed solely on clinical presentation
(7/75, 9%) or on CXR (2/75, 3%). During the
decentralised Xpert period, 99% (77/78) of cases
were bacteriologically confirmed (76 using Xpert, 1
using culture), only one case was diagnosed by CXR,
and none clinically. During the centralised Xpert
period, 91% (41/45) of cases were bacteriologically
confirmed (38 using Xpert and 3 using culture); 2
cases were diagnosed by CXR and 2 clinically. Of 99
children evaluated for TB, 3 (3%) were diagnosed
with active TB: 2 were microbiologically confirmed
(1 by smear microscopy and 1 by Xpert) and 1 Xpertnegative child was diagnosed based on a suggestive
CXR.
Burden of HIV-associated TB and MDR-TB
Of the 198 TB cases, 137 (69%) were tested for HIV.
Among those tested, the HIV prevalence was similar
during the three study periods (32%, 27% and 23%,
respectively, P . 0.30 for all pairwise comparisons),
lower than the estimated 65% HIV prevalence among
TB patients in South Africa.16
Only 2 of the 198 cases were RMP-resistant (both
detected using Xpert), of which one was also resistant
to isoniazid, giving an MDR-TB prevalence of 0.5%
(95% confidence interval [CI] 0.1–2.8).
TB treatment initiation
The proportion of bacteriologically confirmed TB
cases who initiated treatment was lowest (89%)
during the smear microscopy period and similar
(99% or 100%) during the two Xpert periods (Table
2). Five of the seven individuals who failed to start
treatment during the smear microscopy period had
scanty acid-fast bacilli on a single sputum sample; one
was smear-negative, culture-positive after 23 days;
and one was lost to follow-up.
The median time to treatment was 11.5 days
(interquartile range [IQR] 6–24) during the smear
microscopy period: 8 days (IQR 4–13) in smearpositive individuals and 34 days (IQR 30–40) in
smear-negative, culture-positive individuals (Figure
396
The International Journal of Tuberculosis and Lung Disease
Table 2 Characteristics of 1449 individuals evaluated using microbiological methods for presumptive TB and 196 TB cases
diagnosed at health care facilities in Central Karoo, Western Cape Province, South Africa, stratified by type of initial assay (smear
microscopy or XpertW MTB/RIF) and location of Xpert system (decentralised at health care facilities or centralised at laboratories)
1
Smear
microscopy period
n (%)
2
Decentralised
Xpert period
n (%)
3
Centralised
Xpert period
n (%)
Observation days
510 (33)
510 (33)
510 (33)
Individuals assessed for TB
584 (40)
375 (26)
490 (34)
Sex*
Male
Female
312 (54)
268 (46)
202 (54)
170 (46)
258 (53)
227 (47)
Age, years*
,5
5–14
715
27 (5)
25 (4)
528 (91)
1 (0)
10 (3)
361 (97)
13 (3)
23 (5)
449 (93)
48 (8)
75
76 (20)
78
38 (8)
45
18 (32)
38 (78)
15 (27)
41 (73)
10 (23)
33 (77)
76 (97)
1 (1)
1 (1)
38
3
2
2
Test positivity rate (smear or Xpert)
Number of TB diagnoses made
HIV status among TB cases†
Positive
Negative
Basis of TB diagnosis
Smear-positive
Smear-negative, culture-positive
Xpert-positive
Xpert-negative, culture positive
X-ray-positive
Clinical symptoms only
1 vs. 2
P value
2 vs. 3
P value
1 vs. 3
P value
0.878
0.748
0.846
,0.001
0.005
0.235
,0.001
,0.001
0.780
0.535
0.689
0.332
48 (64)
18 (24)
2 (3)
7 (9
(84)
(7)
(4)
(4)
Bacteriologically confirmed cases
66 (88)
77 (99)
41 (91)
0.008
0.059
0.765
Bacteriologically confirmed cases started on treatment
59 (89)
76 (99)
41 (100)
0.024
1.000
0.042
* Missing in 12 individuals (4 in smear microscopy period, 3 in facility-Xpert period and 5 in laboratory-Xpert period).
†
Percentage is expressed among those diagnosed with TB tested for HIV; HIV status was missing in respectively 19 (25%), 22 (28%) and 2 (4%) TB cases in the
smear microscopy, decentralised Xpert and centralised Xpert periods.
TB ¼ tuberculosis; HIV ¼ human immunodeficiency virus.
2). The median time to treatment dropped to 1 day
(IQR 0–2) during the decentralised Xpert period and
increased again to 6 days (IQR 2–9) during the
centralised Xpert period.
DISCUSSION
In the sparsely populated communities of the Karoo,
access to the Xpert assay and choice of placement of
the Xpert instrument influenced the diagnostic
decision making of HCWs and time to treatment
initiation.
The proportion of people receiving a bacteriologically confirmed diagnosis of TB increased by 11%
(from 88% to 99%), and HCWs were less likely to
make a clinical or radiological diagnosis of TB when
centralised smear microscopy was replaced by decentralised Xpert. When sputum samples were no longer
processed at the facility level but sent to centralised
laboratories for Xpert, HCWs reverted to making
more clinical and radiological diagnoses, reducing the
proportion of patients with bacteriologically confirmed cases from 99% to 91%.
The total number of cases detected did not
increase following the introduction of Xpert, but a
higher proportion of cases diagnosed initiated anti-
tuberculosis treatment (91% vs. 99% or 100%), and
treatment was initiated sooner following sputum
collection. The switch from smear microscopy to
Xpert at centralised NHLS laboratories reduced the
median time to treatment by 5.5 days, from 11.5 to 6
days. The median time to treatment of 6 days during
the centralised Xpert period was similar to the 8-day
delay for smear-positive patients during the smear
microscopy period, suggesting that the faster treatment initiation following the introduction of Xpert
is attributable to the higher sensitivity of Xpert
compared to smear microscopy, thereby reducing
reliance on the lengthy culture process. Placement of
Xpert at facility level during the decentralised Xpert
period enabled same-day treatment for most patients, and reduced the time to treatment by a
median of 5 days (from 6 days to 1 day) compared to
the centralised Xpert period. Enabling same-day
treatment initiation is important for economically
deprived individuals in the rural Karoo who often
have to travel long distances to reach the health care
facilities.
The observed increase in bacteriological confirmation and reduced time to treatment are similar to
observations in urban settings in sub-Saharan Africa.10 The lack of increase in case finding is in contrast
Impact of Xpert in rural settings
397
may limit the generalisability of the findings to other
settings.
CONCLUSIONS
Figure 2 Time to treatment initiation from first sputum
collection among 196 tuberculosis cases diagnosed during three
study periods: smear microscopy, decentralised Xpert and
centralised Xpert period. Full horizontal line represents the
median, box represents the 25th to 75th percentiles, short
horizontal bars represent the 5th and 95th percentiles, open
diamond represents the mean and open circles the outliers.
* One outlier (treatment started at 94 days) not shown on
graph. IQR ¼ interquartile range.
predictions,8
to model
but is in line with two recent
studies that found little or no impact of Xpert on case
finding compared to smear microscopy,9,17 due, in
part, to high rates of empiric treatment. In contrast to
other findings, the lower treatment initiation rate we
observed during the smear microscopy period was not
due to loss to follow-up during the diagnostic
process,18 but was primarily due to HCWs not
treating those individuals with a single scanty positive
smear microscopy result.
Placement of the diagnostic assay also influenced
the positivity rate of the initial test: 8% of samples
sent to centralised laboratories for smear microscopy
were positive, compared to 20% of samples processed by Xpert at facility level, and 8% of samples
processed using Xpert in centralised laboratories.
With good case detection, approximately 10% of
sputum samples should be smear-positive.19 These
findings suggest that HCWs restricted the use of
Xpert when it was performed at facility level. Clinic
staff attributed this finding to stricter adherence to TB
screening criteria because of the perceived high cost
of Xpert. An additional factor may have been the
extra time required by HCWs to perform the Xpert
assay.
While our results are one of the first to demonstrate
the impact of Xpert in rural areas, they must be
interpreted in the light of its limitations. Notwithstanding the 6-month duration of each of the three
study periods and the inclusion of 91% of the Central
Karoo population outside of the capital city, the low
population density resulted in small numbers of TB
cases diagnosed in each of the three study periods.
The unique characteristics of the Karoo population
Our results show a substantial benefit of introducing
Xpert as the initial diagnostic in areas with poor
access to TB diagnostics, even when the burden of
HIV-associated and MDR-TB is relatively low. The
limited investment of the decentralised placement of
three single one-module Xpert instruments and the
training of one nurse per health care facility increased
the proportion of patients receiving a bacteriological
confirmation of TB and reduced the time to treatment
initiation, but may have resulted in fewer people
being evaluated for TB. In addition to targeting
individuals suspected of HIV-associated or MDR-TB
as currently recommended, prioritising Xpert to areas
with poor access to TB diagnostics could expand the
patient impact of Xpert implementation.
Acknowledgements
The authors would like to thank the Western Cape Department of
Health and especially H Schumann (District Director) and A Jooste
(District HAST Director) and their team: J Nel, F Fass, A Adams
and R Koorts; A Swartz, M Poolman and J Arendse at the
Provincial office for their support; I Noordien and L Scott from the
National Health Laboratory Services (Johannesburg, South Africa)
for their input and advice; L Page-Shipp for support; and M Karsten
and the Right to Care Western Cape team for their assistance.
Funding for this study was provided by the United States Agency
for International Development/President’s Emergency Plan for
AIDS Relief under Agreement No. 674-A-00-08-0007-00 to Right
to Care.
Conflicts of interest: none declared.
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Impact of Xpert in rural settings
i
RESUME
L’impact de la mise en œuvre du
MTB/RIF et du choix de l’emplacement des appareils de
laboratoire sur la prise en charge du patient dans des
régions peu peuplées avec un accès médiocre aux services
de laboratoire et de radiologie n’a pas encore été élucidé.
M É T H O D E S : Evaluation prospective de trois approches
diagnostiques dans la région de Central Karoo, Afrique
du Sud : microscopie de frottis pour le diagnostic initial
avec traitement des crachats dans des laboratoires
centralisés et Xpert pour le diagnostic initial avec une
affectation des appareils au niveau des structures de
soins ou d’un laboratoire central.
R É S U LT A T S : Au total, 196 cas de tuberculose (TB) ont
été diagnostiqués chez 1449 individus. La proportion de
cas positifs parmi les tests initiaux a été de 8%, 20% et
8% lors de la période de microscopie de frottis, de Xpert
CONTEXTE :
Xpertw
décentralisé et de Xpert centralisé, respectivement. La
proportion de cas confirmés bactériologiquement a été de
88%, 99% et 91% pendant la période de microscopie de
frottis, de Xpert décentralisé et de Xpert centralisé,
respectivement. Le délai médian de traitement a été de
11,5 jours (IQR 6–24), 1 jour (IQR 0–2) et 6 jours (IQR
2–9) pendant la période de microscopie de frottis, de
Xpert décentralisé et de Xpert centralisé, respectivement.
C O N C L U S I O N : Introduire le Xpert comme diagnostic
initial dans des régions ayant un accès limité au
diagnostic de TB a accru la proportion de cas avec
confirmation bactériologique et amené une réduction du
délai de mise en route du traitement anti-tuberculeux,
mais la localisation des tests aux points de service peut
avoir diminué le nombre de personnes bénéficiant d’un
diagnostic.
RESUMEN
M A R C O D E R E F E R E N C I A: No se ha estudiado la
repercusión de la introducción de la prueba Xpertw
MTB/RIF y de la ubicación del dispositivo sobre la
atención al paciente en las zonas de baja densidad de
población y con escaso acceso a los servicios de
laboratorio y radiologı́a.
M E T O D O S: En el distrito Central Karoo de Suráfrica se
llev ó a cabo una evaluaci ón prospectiva de tres
estrategias diagnósticas, a saber: la baciloscopia como
prueba diagnóstica inicial con procesamiento del esputo
en laboratorios centralizados, la prueba Xpert como
examen inicial y ubicación del dispositivo en el centro de
atención o en un laboratorio centralizado.
R E S U L T A D O S: Se diagnosticaron 196 casos de
tuberculosis (TB) en 1449 personas. La proporción de
pruebas iniciales positivas fue 8% durante el perı́odo de
la baciloscopia, 20% con la prueba Xpert
descentralizada y 8% durante el perı́odo de la prueba
Xpert en un laboratorio central. La proporción de casos
confirmados bacteriológicamente fue 88% durante el
periodo de la baciloscopia, 99% con la prueba Xpert
descentralizada y 91% con la prueba Xpert centralizada.
La mediana del lapso hasta comenzar el tratamiento fue
11,5 dı́as (intervalo intercuartil [IQR] 6–24) con la
baciloscopia, 1 dı́a (IQR 0–2) durante el perı́odo de la
prueba Xpert periférica y 6 dı́as (IQR 2–9) con la prueba
Xpert en el laboratorio central.
C O N C L U S I O N: La introducción de la prueba Xpert
como el examen diagnóstico inicial en zonas con
escaso acceso a los métodos diagnósticos de la TB
aument ó la proporci ón de casos confirmados
bacteriológicamente y disminuyó el lapso hasta el
comienzo del tratamiento antituberculoso; sin
embargo, la ubicación del dispositivo en el punto de
atención tal vez disminuyó el número de personas en
quienes se investigó el diagnóstico de TB.