How did the study come about?
According to World Health Organization (WHO) estimates, 33.4 million people were infected
with the human immunodeficiency virus (HIV) type 1 globally at the end of 2008.
1
Sub-Saharan Africa and Asia are the two regions that have the highest HIV prevalence,
with 22.4 and 4.7 million people infected, respectively.
1
During the 5 years prior, access to combination antiretroviral therapy (ART) in low-
and middle-income countries increased 10-fold to reach 4 million people, providing
coverage to 28% of those in need.
2
Several studies have reported significant reductions in HIV-related morbidity and
mortality for individuals with access to treatment in these regions.
3–5
In resource-limited settings, to facilitate the rapid expansion of access to ART,
WHO recommends a standardized, public-health approach.
6
This is in contrast to the individualized patient-management strategies in developed
countries, based on routinely available diagnostic monitoring.
7
Standardized first-line ART regimens consist of a non-nucleoside reverse transcriptase
inhibitor (NNRTI) and a dual nucleoside/nucleotide reverse transcriptase inhibitor
(NRTI) backbone, available in some countries as generic fixed-dose combinations.
6
Recommended second-line regimens combine a ritonavir-boosted protease inhibitor (PI)
with two previously unused and/or recycled NRTIs.
6
Routine HIV viral-load monitoring is not generally available in resource-limited countries
and treatment failure is frequently identified based on immunological definitions
and/or the occurrence of clinical events.
6
Virological breakthrough may be detected late while the failing regimen is continued,
thus facilitating the acquisition and accumulation of drug resistance-associated mutations.
8
Drug-resistant HIV variants may compromise the effectiveness of subsequent lines of
treatment and their transmission to newly infected individuals has severe public health
consequences.
9
,
10
To date, ART programmes have been implemented without accompanying HIV drug resistance
(HIVDR) monitoring. Monitoring studies are hampered by the lack of a molecular laboratory
infrastructure required for genotypic resistance testing, logistical challenges related
to maintaining specimen integrity in remote settings and the high costs of testing.
11
Challenges to scaling up ART in resource-limited countries, such as absence of routine
virological monitoring and limited choices of drug regimen, advocate for the development
of a global public-health framework to monitor and prevent the emergence of HIVDR
and thus maximize long-term ART effectiveness.
12
HIV-1 subtype B is the predominant viral subtype in North America, Western Europe
and Australia, and antiretroviral (ARV) drugs have been developed on this subtype.
However, in sub-Saharan Africa and Asia, the genetic diversity in HIV subtypes and
circulating recombinant forms (CRFs), resulting from recombination between subtypes
within a dually infected person, is extensive.
13
Although current evidence is limited, some reports have suggested that the propensity
to develop HIVDR and the spectrum of mutations that emerge during drug selective pressure,
may differ across subtypes and CRFs.
14–17
Viral heterogeneity may, therefore, have implications for rates of disease progression
and patient response to ART, warranting further study of inter-subtype differences
in mutational pathways to resistance.
To help assess the extent of HIVDR in sub-Saharan Africa and Asia, a collaborative
bi-regional programme was established, called LAASER [Linking African and Asian Societies
for an Enhanced Response (LAASER) to HIV/AIDS; http://www.laaser-hivaids.org] with
the primary aim of increasing regional capacities for the monitoring of HIVDR. PharmAccess
Foundation, a non-profit organization dedicated to the strengthening of health systems
and improving access to quality basic health care in sub-Saharan Africa, has developed
the PharmAccess African Studies to Evaluate Resistance (PASER). TREAT Asia (Therapeutics,
Research, Education and AIDS Training in Asia) is a network of clinics, hospitals
and research institutions working to ensure safe and effective delivery of HIV/AIDS
treatment throughout the Asia-Pacific and has developed the TREAT Asia Studies to
Evaluate Resistance (TASER). Both PASER and TASER programmes incorporate a monitoring
and evaluation (M) and a surveillance (S) protocol. Laboratories providing genotyping
results for PASER and TASER are required to participate in the TREAT Asia Quality
Assurance Scheme (TAQAS), which is an ongoing assessment programme to build genotyping
laboratory capacity, described elsewhere.
18
The focus of this cohort profile is the monitoring and evaluation protocols, PASER-M
and TASER-M.
How are PASER and TASER set up and how are they funded?
Through the LAASER programme, PASER and TASER receive financial support from the Dutch
Ministry of Foreign Affairs through a partnership with Stichting Aids Fonds, PharmAccess
Foundation, TREAT Asia (a programme of amfAR, The Foundation for AIDS research) and
International Civil Society Support. PASER-M is coordinated by PharmAccess Foundation,
in collaboration with the Amsterdam Institute for Global Health and Development (AIGHD)
and the Virology Department at the University Medical Center Utrecht, The Netherlands.
TASER-M is coordinated by TREAT Asia and its statistical and data management centre
is the National Centre in HIV Epidemiology and Clinical Research (NCHECR), The University
of New South Wales in Sydney, Australia.
PASER constitutes a newly established collaboration between HIV treatment clinics,
laboratories with the capacity to perform genotypic sequencing and research centres.
Thirteen clinical sites and two reference laboratories in six African countries (Kenya,
Nigeria, South Africa, Uganda, Zambia and Zimbabwe) are collaborating on PASER-M (Figure
1a). Details of the PASER-M collaborating clinical sites are summarized in Supplementary
Table 1 available as Supplementary data at IJE online. Ethics approvals were obtained
from the Academic Medical Center Institutional Review Board (IRB) and local IRBs.
Sites are government, non-government, faith-based or private clinics and hospitals,
situated in major cities or urban areas. ART was introduced at the sites at various
time points between 1992 and 2006 (median: 2004). Of the 13 sites, 11 provided drugs,
consultations and routine laboratory testing free of charge. HIV viral load testing
is available at 8 of the 13 sites.
TASER collaborating sites are selected from within the existing TREAT Asia network,
based on their laboratory capacity to perform genotypic sequencing, as described elsewhere.
18
,
19
Sites that do not have internal laboratory genotyping capacity can participate through
collaboration with a TAQAS-certified laboratory. Eleven clinical and laboratory sites
in six Asian countries (China, Indonesia, Malaysia, Philippines, South Korea and Thailand)
are collaborating on TASER-M (Figure 1b). Ethics approvals were obtained from local
IRBs having Federal wide Assurances (FWAs) in place from the United States Office
for Human Research Protections. FWAs are required for TASER sites as they participate
in the International Epidemiologic Databases to Evaluate AIDS (IeDEA) initiative,
described elsewhere.
20
Sites are generally government- or university-based clinics and hospitals or private
clinics, situated in major cities and other urban areas. Those with ethics approvals
prior to June 2010 are shown in Figure 1b. ART has been available in Asia for more
than 10 years, even in less-resourced countries in the region, and all TASER-M clinical
sites have on-site viral load testing.
Figure 1
Geographical location of (a) PASER-M collaborating sites and (b) TASER-M collaborating
sites
Clinical sites follow their national guidelines to assess eligibility for ART initiation
in accordance with the WHO recommendations.
6
Genotypic resistance testing on PASER and TASER clinical specimens are performed in
TAQAS-certified genotyping laboratories.
18
Laboratories are encouraged to become accredited members of the WHO/HIVResNet HIV
Drug Resistance Laboratory network.
21
Population-based nucleotide sequencing of the HIV protease (PR) and partial reverse
transcriptase (RT) gene regions is performed on plasma specimens, which have HIV RNA
of more than 1000 copies/ml. Plasma is obtained from blood collected in EDTA tubes
which is locally stored at −80°C and, if required, batch-shipped on dry ice to a genotyping
laboratory.
PASER-M genotypic testing is concentrated in two central reference laboratories and
thus depends on a robust cold-chain and web-based specimen tracking system for managing
specimen shipments. Approximately half of TASER-M clinical sites have an on-site or
local genotyping laboratory. Most genotyping laboratories amplify viral sequences
using in-house methods, based on assembled commercially available assay components
and laboratory-specific sequencing and amplification primers. One TASER laboratory
uses the commercial kit TruGene (Bayer HealthCare, Tarrytown, NY, USA). The online
Stanford interpretation system is used by most laboratories to identify drug resistance-associated
mutations.
22
Resistance genotyping is generally performed retrospectively (i.e. not real-time)
for all participants. Details of the genotyping laboratories are summarized in Supplementary
Table 2 available as Supplementary data at IJE online. PASER and TASER sequences are
submitted to the ViroScore database (Advanced Biological Laboratories SA, France)
for data storage.
What do PASER-M and TASER-M cover and who is included in the sample?
The monitoring studies are multi-centre prospective cohort designs with sequential
patient enrolment. Patient eligibility criteria are listed in Table 1. The main study
objectives are to assess prevalence and incidence of HIVDR, mutational patterns and
factors associated with HIVDR in persons initiating first-line ART or switching to
a second-line regimen due to treatment failure under routine circumstances. Participants
are required to sign informed consent prior to study enrolment and must initiate or
switch ART within 30 days (PASER-M) or 181 days (TASER-M) following baseline specimen
collection. Regimen switch due to treatment failure may be determined clinically,
as assessed by disease progression, immunologically, by CD4 cell count or virologically,
by HIV viral load. A single drug substitution, due to toxicity or intolerance, is
not considered a regimen switch. Each site aims to recruit a total of 240 participants.
Second-line participants are recruited among first-line participants failing therapy
and the clinical site patient population. The recommended maximum site-specific enrolment
period is 18 months.
Table 1
Patient eligibility criteria for PASER-M and TASER-M
Inclusion criteria
Confirmed HIV-1 infection
≥18 years of age
Eligible
a
for initiation of a first-line ART regimen or switch from a first-line ART regimen
(containing at least three antiretroviral drugs and taken for ≥6 months) to a second-line
ART regimen due to virological, immunological and/or clinical failure
Signed informed consent for study participation prior to enrolment
Exclusion criteria
Currently taking ART (minimum of three-drug regimen), if initiating a first-line
ART regimen
b
Pregnancy at enrolment
c
HIV-1/2 dual infection (in endemic countries only)c
aEligibility for ART initiation defined in accordance with national ART guidelines
(i.e. advanced immunodeficiency as defined by CD4 cell count less than 200 or less
than 350 cells/µl, or advanced clinical disease according to WHO clinical stage/CDC
classification).
bSpecified PASER-M definition: re-initiation of a first-line ART regimen <30 days
after stopping previous first-line ART (previous use of antiretroviral prophylaxis
or mono/dual therapy is not an exclusion criterion).
cExclusion criteria applicable to PASER-M only.
How often are participants followed-up? What data are being collected?
Participants are followed-up as per local standard of care guidelines. The frequency
of follow-up visits for patients varies by site (range: every 1–6 months). The studies
make use of clinical data collected during routine visits and recorded in medical
records. HIV viral load measurement and, if the HIV RNA value is more than 1000 copies/ml,
genotypic resistance testing is performed on plasma specimens taken at baseline, prior
to regimen switch due to treatment failure and at annual follow-up. For patients failing
a first-line regimen, the treatment failure data collection becomes the new baseline
for the second-line regimen. Annual follow-up is then calculated from this point.
For patients failing a second-line ART, the treatment failure data collection is the
final assessment prior to the patient going off study.
PASER-M clinical data are recorded on standardized hard-copy data forms, which are
completed at 3-monthly intervals and entered in a web-based clinical data system,
called the HAART Monitoring System. PharmAccess performs quality assurance measures,
which include (i) source data verification during 3- to 6-monthly site audits, (ii)
checks to identify data entry inconsistencies or suspect data values and (iii) specimen
tracking. TASER-M site personnel extract clinical data from site databases and medical
records collected as part of usual care. From March 2008 to March 2009, TASER-M data
were submitted electronically to NCHECR on a quarterly basis, as part of study start
up, then at 6-monthly intervals. At each transfer, NCHECR performs quality assurance
measures, which include (i) checks to identify data entry inconsistencies or suspect
data values, (ii) specimen tracking and (iii) ARV history completeness. Annually,
a random 10% of TASER-M patients are selected for internal site audit where submitted
data are compared with patient medical records.
The studies capture standardized virological and genotypic data at protocol determined
intervals. Genotyping data consist of HIV subtype and HIVDR mutations, including insertions
and deletions. TASER-M also records discordant subtypes, i.e. when the PR and RT region
subtypes differ. Laboratory specimen tracking information is recorded during specimen
processing, allowing assessment of pre-analytical and assay validity. Genotyping laboratories
complete an annual laboratory survey that includes the dynamic range of the virological
assay used, the regions of PR and RT genome routinely sequenced and the interpretation
algorithm used. Observational patient data includes demographic parameters, physical
measures, Centres for Disease Control and Prevention (CDC) class (TASER-M) or WHO
clinical stage (PASER-M), serology of hepatitis and syphilis (TASER-M), opportunistic
infections, current ART regimen, ARV history, concomitant medications, routine laboratory
parameters (including CD4 counts) and assessment of drug adherence. Main analyses
will include age, sex, ethnicity, HIV exposure category, WHO clinical stage (PASER-M)
or CDC class (TASER-M), viral hepatitis co-infection status, CD4 count, HIV viral
load, HIV subtype, drug adherence, ARV history and ART regimen as covariates. Predictors
of drug resistance will be assessed using logistic regression models. Incidence of
drug resistance will be summarized using person-years methods and Kaplan–Meier plots.
Cox proportional hazards models will be used to assess risk factors associated with
developing drug resistance.
What is the anticipated attrition?
The actual attrition in PASER-M and TASER-M cannot currently be accurately estimated
because the duration of follow-up in the databases is still limited. In sub-Saharan
Africa patient retention in routine ART programmes has been estimated at 61.623 to
66.8%
2
at 24 months on ART, attrition being mainly due to loss of follow-up and early death.
23
Therefore, in PASER-M, the original site-specific sample size was calculated accounting
for 20% loss to follow-up and 25% mortality after 24 months. Attrition is expected
to vary between sites as a result of differences in patient populations, care provided
and provisions for tracing lost to follow-up. TASER-M sites are generally sourced
from the ongoing TREAT Asia HIV Observational Database (TAHOD).
19
Loss to follow-up for TAHOD was 6.9/100 person-years for the 12-month period from
September 2007 to September 2008. Since TASER-M monitors specified outcomes, we speculate
that TASER-M follow-up will be similar to TAHOD or better.
What has been found?
PASER-M
Patient recruitment commenced in March 2007 and was completed in September 2009. Of
the 13 sites, 12 reached the site-specific target of 240 participants, enrolling a
total of 3005 participants. Excluding patients with protocol violations (n = 16) and
key data missing (n = 4), 2985 patients were included in the analysis. Of these, 2736
(91.6%) were eligible for a first-line ART regimen and 249 (8.3%) were eligible for
second-line ART due to treatment failure. Patient characteristics are summarized in
Table 2. For first-line patients, the median age was 36.8 years [inter-quartile range
(IQR) 31.3–42.6] and 58% were women. HIV exposure was predominantly reported as heterosexual
contact. More than 60% had advanced disease (classified as WHO stages III or IV) and
37% had pre-therapy CD4 counts of less than 100 cells/µl. Across all 13 sites, median
baseline CD4 counts of first-line patients were less than 200 cells/µl (site median
135 cells/μl, range 93–191). Median baseline HIV viral load was 4.9 log10 copies/ml
(IQR 4.2–5.5). The most frequently prescribed first-line regimens were based on NNRTIs
(99.7%), i.e. efavirenz (EFV) and nevirapine (NVP) at 60 and 40%, respectively. First-line
dual NRTI backbones were predominantly lamivudine (3TC)/zidovudine (AZT) (37%), emtricitabine
(FTC)/tenofovir (TDF) (34%) and 3TC/stavudine (d4T) (26%). Overall, 67% of patients
started a 3TC-containing first-line regimen. Among patients initiating first-line
ART, 95% (n = 2 598) reported to be ARV-naive and 5% (n = 138) had previous ARV experience,
which included ART (n = 60), mono/dual therapy (n = 6), single-dose NVP for prevention
of mother-to-child transmission of HIV (PMTCT) (n = 35), combination therapy for PMTCT
(n = 19), and unspecified (n = 22). Compared with ARV-naive first-line patients, ARV-experienced
first-line patients had higher median CD4 counts (177 vs 133 cells/μl, P < 0.0001),
were younger (median 34.7 vs 37.0 years, P < 0.0001) and were more likely to be female
(76.1 vs 57.5%; P < 0.001). Other baseline characteristics did not differ between
ARV-naive and ARV-experienced patients.
Table 2
Baseline patient characteristics, by region and line of ART
PASER-M (Africa)
TASER-M (Asia)
Initiation of first-line ART
a
Switch to second-line ART
b
Initiation of first-line ART
a
Switch to second-line ART
b
Total
ARV-naive
ARV-experienced
c
ARV-naive
ARV-experienced
c
Patients, n (%)
3713
2598 (87.0)
138 (4.6)
249 (8.3)
693 (95.2)
10 (1.4)
25 (3.4)
Sex
Female, n (%)
1988 (53.5)
1494 (57.5)
105 (76.1)
124 (49.8)
239 (34.5)
10 (100.0)
16 (64.0)
Male, n (%)
1725 (46.5)
1104 (42.5)
33 (23.9)
125 (50.2)
454 (65.5)
0 (0.0)
9 (36.0)
Age (years), median (IQR)
36.9 (31.7–43.3)
37.0 (31.2–42.8)
34.7 (29–2–40.2)
38.6 (32.9–44.2)
36.5 (31.1–43.2)
33.1 (27.4–38.4)
36.5 (32.4–41.9)
18–29
707 (19.0)
490 (18.9)
39 (28.3)
28 (11.2)
143 (20.6)
3 (30.0)
4 (16.0)
30–39
1668 (44.9)
1176 (45.3)
65 (47.1)
112 (45.0)
298 (43.0)
5 (50.0)
12 (48.0)
≥40
1338 (36.0)
932 (35.9)
34 (24.6)
109 (43.8)
252 (36.4)
2 (20.0)
9 (36.0)
HIV exposure, n (%)
Heterosexual contact
2583 (69.6)
1731 (66.6)
108 (78.3)
191 (76.7)
520 (75.0)
10 (100.0)
23 (92.0)
Homosexual contact
134 (3.6)
4 (0.2)
0 (0.0)
0 (0.0)
128 (18.5)
0 (0.0)
2 (8.0)
Other
d
996 (26.8)
863 (33.2)
30 (21.7)
58 (23.3)
45 (6.5)
0 (0.0)
0 (0.0)
WHO clinical stages, n (%)
I
493 (16.5)
393 (15.1)
25 (18.1)
75 (30.1)
na
na
na
II
711 (23.8)
623 (24.0)
33 (23.9)
55 (22.1)
na
na
na
III
1281 (42.9)
1145 (44.1)
59 (42.8)
77 (30.9)
na
na
na
IV
500 (16.7)
437 (16.8)
21 (15.2)
42 (16.9)
na
na
na
CDC classification, n (%)
A
302 (41.5)
na
na
na
296 (42.7)
0 (0.0)
6 (24.0)
B
166 (22.8)
na
na
na
152 (21.9)
10 (100.0)
4 (16.0)
C
260 (35.7)
na
na
na
245 (35.4)
0 (0.0)
15 (60.0)
Ever pulmonary tuberculosis, n (%)
741 (20.0)
569 (21.9)
25 (18.1)
74 (29.7)
69 (10.0)
na
4 (16.0)
Hepatitis B
e
, n (%)
36 (4.9)
na
na
na
35 (5.1)
0 (0.0)
1 (4.0)
Hepatitis C
f
, n (%)
56 (7.7)
na
na
na
55 (7.9)
0 (0.0)
1 (4.0)
History of ARV drug use, n (%)
422 (11.4)
na
138 (100.0)
249 (100.0)
na
10 (100.0)
25 (100.0)
ART
334 (9.0)
na
60 (43.5)
249 (100.0)
na
0 (0.0)
25 (100.0)
Mono or dual therapy
10 (0.3)
na
6 (4.3)
4 (1.6)
na
0 (0.0)
0 (0.0)
Single-dose NVP for PMTCT
36 (1.0)
na
35 (25.4)
1 (0.4)
na
0 (0.0)
0 (0.0)
Combination therapy for PMTCT
31 (0.8)
na
19 (13.8)
2 (0.8)
na
10 (100.0)
0 (0.0)
Unspecified
22 (0.6)
na
22 (15.9)
0 (0.0)
na
0 (0.0)
0 (0.0)
CD4 cell count (cells/μl), median (IQR)
129 (56–205)
133 (62–204)
177 (92–262)
125 (46–-196)
99 (33.5–201)
169 (151–222)
197 (109–299)
<100
1456 (39.2)
975 (37.5)
38 (27.5)
102 (41.0)
337 (48.6)
1 (10.0)
3 (12.0)
100–199
1215 (32.7)
914 (35.2)
42 (30.4)
81 (32.5)
164 (23.7)
6 (60.0)
8 (32.0)
≥200
1007 (27.1)
702 (27.0)
57 (41.3)
64 (25.7)
171 (24.7)
3 (30.0)
10 (40.0)
Unknown
25 (0.7)
7 (0.3)
1 (0.7)
2 (0.8)
21 (3.0)
0 (0.0)
4 (16.0)
HIV-1 RNA (log10 copies/ml), median (IQR)
4.9 (4.3–5.5)
4.9 (4.3–5.6)
4.8 (4.2–5.5)
4.1 (3.2–5.0)
5.0 (5.4–6.8)
4.8 (4.5–5.0)
4.0 (3.6–4.5)
ART regimen
NNRTI-based triple regimen
3330 (89.7)
2590 (99.7)
135 (97.8)
2 (0.8)
593 (85.6)
10 (100.0)
0 (0.0)
AZT-containing
1302 (35.1)
964 (37.2)
51 (37.8)
1 (0.4)
170 (28.7)
10 (100.0)
0 (0.0)
TDF-containing
1088 (29.3)
868 (33.5)
49 (36.3)
1 (0.4)
110 (18.5)
0 (0.0)
0 (0.0)
d4T-containing
833 (22.4)
690 (26.6)
33 (24.4)
0 (0.0)
276 (46.5)
0 (0.0)
0 (0.0)
ABC-containing
106 (2.9)
68 (2.6)
2 (1.5)
0 (0.0)
37 (6.2)
0 (0.0)
0 (0.0)
3TC-containing
2387 (71.7)
1746 (67.4)
89 (65.9)
0 (0.0)
542 (91.4)
10 (100.0)
0 (0.0)
FTC-containing
942 (28.3)
843 (32.5)
48 (35.6)
0 (0.0)
49 (8.3)
0 (0.0)
0 (0.0)
PI-based triple regimen
351 (9.5)
6 (0.2)
0 (0.0)
247 (99.2)
73 (10.5)
0 (0.0)
25 (100.0)
Triple NRTI regimen
29 (0.8)
2 (0.1)
3 (2.2)
0 (0.0)
24 (3.5)
0 (0.0)
0 (0.0)
NNRTI+PI-based triple regimen
3 (0.1)
0 (0.0)
0 (0.0
0 (0.0)
3 (0.4)
0 (0.0)
0 (0.0)
Data are n (%) of patients, unless otherwise indicated. na, not available; ART, combination
antiretroviral therapy; ARV, antiretroviral; CDC, US Center for Disease Control and
Prevention; WHO, World Health Organization; PMTCT, prevention of mother-to-child transmission
of HIV-1; TB, tuberculosis; IQR, interquartile range; NVP, nevirapine; d4T, stavudine;
AZT, zidovudine; TDF, tenofovir; ABC, abacavir; 3TC, lamivudine; FTC, emtricitabine;
NRTI, nucleoside reverse transcriptase inhibitor; NNRTI, non-nucleoside reverse transcriptase
inhibitor; PI, protease inhibitor.
aEligibility for ART initiation in accordance with national ART guidelines (i.e. advanced
immunodeficiency as defined by CD4 cell count less than 200 or less than 350 cells/µl,
or advanced clinical disease according to WHO clinical stages or CDC classification).
bRegimen switch due to treatment failure, defined by local standard of care guidelines
as determined clinically, immunologically or virologically.
cARV-experienced is defined as any previous use of ARVs, i.e. (first-line) ART, mono/dual
therapy and/or PMTCT.
dIncludes recipients of blood products, injecting drug users, perinatal transmission
and unknown exposures.
eHepatitis B positive status was defined as being HBsAg positive.
fHepatitis C positive status was defined as being HCV antibody positive.
For the 249 (8.3%) patients switching to second-line ART, the median age was 38.6
years (IQR 32.9–44.2) and sex was equally distributed. HIV exposure was predominantly
heterosexual contact and 48% of patients had advanced disease (classified as WHO stages
III or IV). Median CD4 count was 125 cells/μl (IQR 46–196). Median pre-switch HIV
viral load was 4.1 log10 copies/ml (IQR 3.2–5.0). Ritonavir-boosted lopinavir (LPV)
was the PI used almost exclusively (98%).
As shown in Table 3, analysis of the first available 1795 viral sequences demonstrated
that the most common HIV subtypes in the cohort were C (1216, 68.7%), A (338, 18.7%)
and D (179, 10.0%). The first PASER report published in 2008 reviewed the available
data on HIVDR in sub-Saharan Africa.
11
Baseline HIVDR data from Lusaka, Zambia, has recently been published.
24
International presentations have summarized preliminary baseline HIVDR mutations and
subtype distributions.
25
,
26
Table 3
HIV subtypes and circulating recombinant forms
a
by region and country
PASER-M (Africa)
TASER-M (Asia)
b
Total
South Africa
Zambia
Uganda
Kenya
Nigeria
Zimbabwe
Thailand
Hong Kong
Malaysia
n (%)
2523 (100.0)
624 (24.7)
583 (23.1)
410 (16.3)
140 (5.5)
21 (0.8)
17 (0.7)
542 (21.5)
111 (4.4)
75 (3.0)
A
340 (13.6)
2 (0.3)
4 (0.7)
235 (57.3)
97 (69.1)
1 (4.8)
1 (0.2)
B
114 (4.5)
3 (0.5)
37 (7.0)
55 (49.5)
19 (25.3)
C
1236 (49.2)
617 (98.9)
571 (97.9)
9 (2.2)
19 (13.6)
17 (100.0)
2 (1.8)
1 (1.3)
D
179 (7.1)
1 (0.2)
1 (0.2)
160 (39.0)
17 (12.1)
G
11 (0.4)
2 (0.3)
1 (0.2)
2 (1.4)
6 (28.6)
CRF01_AE
585 (23.2)
485 (89.5)
52 (46.8)
48 (64.0)
CRF02_AG
20 (0.8)
1 (0.2)
3 (0.5)
1 (0.2)
14 (66.7)
1 (0.2)
Other recombinants or discordant subtypes
32 (1.3)
2 (0.3)
1 (0.2)
2 (1.4)
18 (3.3)
2 (1.8)
7 (9.3)
Unclassified
6 (0.2)
3 (0.7)
3 (2.1)
Data are n (%) of subtypes/CRFs, unless otherwise indicated. CRF, circulating recombinant
form.
aHIV subtypes were determined from the pol sequences, using the REGA HIV-1 subtyping
algorithm version 2.0 (http://dbpartners.stanford.edu/RegaSubtyping) and/or Stanford
HIV drug resistance database (http://hivdb.stanford.edu).
bThe collaborating sites in Philippines, South Korea and Indonesia had not yet provided
sequence data at time of the current analysis.
TASER-M
Patient recruitment commenced in March 2007 and for the March 2009 transfer, seven
sites from Thailand, Hong Kong and Malaysia provided data. Of 773 patients, 755 (97.7%)
commenced ART within 181 days of baseline specimen collection and 728 (96.4%) participants
had genotypic data available. Of these, 693 (95.2%) ARV-naive patients and 10 (1.4%)
ARV-experienced patients, following prior PMTCT, were eligible for first-line regimens.
A further 25 (3.5%) patients were eligible for second-line ART following first-line
treatment failure. Patient characteristics are summarized in Table 2. For ARV-naive
first-line patients, the median age was 36.5 years. Almost two-thirds of patients
were male and HIV exposure was predominantly heterosexual contact. More than one-third
of patients were classified as CDC class C and almost half of the patients had pre-therapy
CD4 counts less than 100 cells/µl. Median baseline HIV viral load was 5.0 log10 copies/ml
(IQR 5.4–6.8) and the most common first-line regimens were based on NNRTIs (85.6%).
Excluding 14 (2.4%) patients on a randomized clinical trial with a blinded NNRTI component,
NVP was more commonly prescribed than EFV at 56 and 42%, respectively. First-line
dual NRTI backbones were predominantly 3TC/d4T (47%), 3TC/AZT (29%) and 3TC/TDF (10%).
For first-line PI regimens, the favoured NRTI backbone was FTC/TDF (33%) compared
with 3TC/d4T (30%) or 3TC/AZT (18%). For the ritonavir-boosted PI component, atazanavir
(ATZ) was only slightly favoured over LPV at 43 vs 41%, respectively. Overall, 542
(91.4%) of ARV-naive patients started a 3TC-containing first-line regimen. The 10
PMTCT patients received perinatal prophylaxis of AZT/3TC/NVP (n = 7), AZT (n = 2)
or AZT/NVP (n = 1) for between 14 and 102 days and all were prescribed AZT/3TC/NVP
as first-line regimens.
For the 25 (3.4%) second-line patients, 22 (88%) were of Thai ethnicity and the median
age was 36.5 years (IQR 32.4–41.9). Females were in the majority (64%), HIV exposure
was predominantly heterosexual (92%) and 60% of patients had experienced at least
one CDC class C event. Of 21 patients with CD4 counts available within 6 months of
starting a second-line therapy, the median CD4 count was 197 (IQR 109–299). Median
pre-switch HIV viral load was 4.0 log10 copies per/ml (IQR 3.6–4.5). All patients
were on PI-based regimens, following failure on first-line NNRTI-based regimens (median
duration 30.3 months). The most commonly prescribed PI component was ritonavir-boosted
LPV (88%).
As shown in Table 3, from analysis of the 728 available viral sequences, the most
common subtypes were CRF01_AE (584, 80.2%) and subtype B (111, 15.2%). Non-CRF01_AE
recombinants were identified in eight (1.1%) patient specimens. For 21 (2.9%) specimens,
the subtype differed between PR and RT regions, suggesting dual infection or recombination.
International presentations have summarized 2009 baseline HIVDR mutations and subtype
distributions.
27
,
28
Complete baseline and prospective outcome data for PASER-M and TASER-M are anticipated
to become available in 2010–13.
What are the main strengths and weaknesses?
Programmes that monitor national and regional levels of primary and secondary HIVDR
contribute to evidence-based recommendations to inform treatment guidelines and provide
feedback on the success of HIV treatment and prevention programmes. PASER and TASER,
with TAQAS, are developing capacity in sub-Saharan Africa and the Asia-Pacific for
coordinated HIVDR monitoring and genotypic laboratory testing. The study protocols
are harmonized with the WHO HIV Drug Resistance Prevention Survey protocol.
29
An important strength is the large number of patients and sites participating, representing
a diverse spectrum of patient populations, clinic types, ART regimens and HIV subtypes.
Opportunities exist to investigate the impact of drug resistance on HIV natural history,
rates of disease progression and response to treatment in non-B subtypes. Data from
genotypic resistance testing will also provide insight into the population genetics
and dynamics of transmitted HIVDR in the region.
PASER-M and TASER-M have several limitations. First, patient samples at each site
are not necessarily representative of the site, country or region. Second, data quality
depends on the completeness of clinical information captured through routine patient
care. In PASER-M, data may have been collected under varying conditions, since some
sites had no or limited research experience at study initiation. Third, at some sites,
study initiation was delayed by several months due to the time required for contract
negotiation, IRB study approval and, in TASER-M, procurement of FWAs. After study
initiation, recruiting the required number of patients within the recommended 18-month
period proved difficult for some sites, due to asymptomatic patients not seeking care
or treatment, cost of medication or low-prevalence in their setting. Fourth, HIVDR
monitoring activities in resource-limited countries in sub-Saharan Africa are limited
by high costs of laboratory testing. To address this challenge, PASER has initiated
a public–private consortium, called Affordable Resistance Test for Africa (ART-A),
which aims to develop affordable test algorithms for the detection and interpretation
of HIVDR for use in laboratories and clinics (http://www.arta-africa.org).
How can I collaborate? Where can I find out more?
Ownership of individual site data remains with the contributing site. Sites are represented
by their principal investigators on the respective PASER and TASER Steering Committees.
Research is to be the subject of peer-reviewed publications and analysis priorities
are driven by a concept sheet process. Both studies accept concept proposals from
external researchers for review, if submitted in collaboration with one or more of
the site principal investigators. The PASER and TASER protocols contribute data under
the LAASER partnership (http://www.laaserhivaids.org) and TASER also contributes data
to IeDEA.
20
Collaborating sites are also encouraged to make an appropriate subset of their data
available to Ministry of Health in their respective countries in order to contribute
to local efforts in monitoring HIVDR. Questions regarding participation, research
concepts or requests for data should be sent to Tobias Rinke de Wit, email: t.rinkedewit@pharmaccess.org
(PASER), or Thida Singtoroj, email: thida.singtoroj@treatasia.org (TASER).
Supplementary Data
Supplementary Data are available at IJE online.
Funding
The PharmAccess African Studies to Evaluate Resistance is an initiative of PharmAccess
Foundation, supported by the Ministry of Foreign Affairs of The Netherlands through
a partnership with Stichting Aids Fonds (grant no 12454). The TREAT Asia Studies to
Evaluate Resistance is an initiative of TREAT Asia, a programme of amfAR, The Foundation
for AIDS Research, with major support provided by the Ministry of Foreign Affairs
of The Netherlands through a partnership with Stichting Aids Fonds (grant no 12454),
and with additional support from amfAR and the National Institute of Allergy and Infectious
Diseases (NIAID) of the U.S. National Institutes of Health (NIH) and the National
Cancer Institute (NCI) as part of the International Epidemiologic Databases to Evaluate
AIDS (IeDEA) (grant no U01AI069907). Queen Elizabeth Hospital and the Integrated Treatment
Centre are supported by the Hong Kong Council for AIDS Trust Fund. The National Centre
in HIV Epidemiology and Clinical Research is funded by the Australian Government Department
of Health and Ageing and is affiliated with the Faculty of Medicine, The University
of New South Wales. The funders had no role in the study design, data collection,
data analysis, data interpretation, decision to publish or writing of the report.
The content of this publication is solely the responsibility of the authors and does
not necessarily represent the official views of any of the institutions mentioned
above.
Supplementary Material
Supplementary Data