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HIV Sentinel Surveillance 2006HIV Sentinel Surveillance 2006
Surveillance UnitNational Center for HIV/AIDS Dermatology and STD
15 August 2008
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Outline
ObjectivesMethodologyMethodologyResults
lConclusionRecommendation
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ObjectivesTo estimate the prevalence of HIV infection in two key female sentinel groups in 2006To estimate HIV incidence in these groupsTo estimate HIV prevalence in the general populationpopulation To obtain data for monitoring trends in HIV prevalenceprevalenceTo provide information on HIV prevalence for prevention planning and care efforts
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MethodsStudy design: Cross sectional study (October 2006-February 2007)Sentinel groups:Sentinel groups:
Brothel based female sex workers (FSW)Pregnant women attending antenatal clinics (ANC)
Sentinel sites: 22 cities/provincesSentinel sites: 22 cities/provincesSample size:
FSW: 150 per provinceANC: 600 per province (300 from provincial capital/urban area and 300 from remaining districts/rural area)
Specimen collected: 5 ml of whole blood
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Methods: 22 sentinel provinces
BMC
OMC
PVHSRP
RTKSTGS
BTBPLN KTM KRT MDK
PSTKCN
KCM
KHK KSP
TAK
PVG
SVRKAN
PHPIncluded
Not included
Tonle Sap Lake
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KPTSHV
TAK
KEP
Methods: Sampling• FSW
• In provinces with less than the required sample size of 150, sampling was “take-all”
• In provinces with at least 150 FSWs, sampling was “take-all” from randomly selected brothels
• ANC• Separate samples of 300 women were selected from provincial
capitals (PC) and 300 from remaining districts (RD)
• Pregnant women were selected consecutively from designated ANC clinics at health centers until the required sample size was reachedclinics at health centers until the required sample size was reached
• Duration of data collection was limited to three months
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Methods: sample size by survey year
2000 2002 2003 2006(Provinces) (21) (20) (22) (22)( ) ( ) ( ) ( ) ( )
DFSW 2,180 2,110 2,411 2,266
IDFSW 1 799 1 232 1 633IDFSW 1,799 1,232 1,633 --
Police 4,711 4,379 5,796 --
ANC 6,562 9,168 10,867 12,464
Total 17 991 19 247 20 707 14 730
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Total 17,991 19,247 20,707 14,730
Methods: HIV testingT f d h i i l l lTests performed at the provincial level
Two rapid tests were used (Determine & Stat-Pak)A serial two-test algorithm was used for FSW and a parallel two-test algorithm was used for ANCgDried blood spot (DBS) specimens were prepared for quality control
Quality control testing performed by NIPH lab FSWFSW:
Phase 1: 10% of all specimens were testedPhase 2: All reactive specimens not tested in phase 1 were tested
ANC: All reactive specimen and 10% of all non-reactive specimens were tested
Two enzyme immunoassays were used for quality control testing (Vironostika & Murex)
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Methods: HIV prevalence testing algorithm
Se=100 0%Determine
Female sex workers ANC women
DetermineSe 100.0%Sp=99.8%
Negative
Determine
Positive Negative
Determine
Positive
Se=99.5%Sp=100.0%Stat-Pak Stat-Pak Stat-Pak
Positive Negative Positive Negative Positive? NegativeR t b th t t
9Sensitivity (Se) and specificity (Sp) data from phase 1 validation of 5 rapid HIV tests conducted in Cambodia in 2004. The combined algorithm was found to be 99.5% sensitive and 100% specific.
Repeat both tests
Methods: Quality control testing algorithm
DBS specimens selected for QC testing
Vironostika
Murex
Positive
NegativePositive Negative
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NegativePositive Negative
Methods: HIV incidence estimationT ti f t i f tiTesting for recent infection
All DBS specimens identified as HIV positive were tested for recent infectionC l t HIV 1 I id BED EIA dCalypte HIV-1 Incidence BED EIA was usedSpecimens with normalized optic density (OD_n) values ≤0.8 on confirmatory testing were considered to be from persons with recent HIV infectionpersons with recent HIV infection
Calculating HIV incidenceOverall window period used was 155 daysHIV i id li d i th f lHIV incidence was annualized using the formula
I =({(365/155)Ninc}/{Nneg+[(365/155)Ninc]/2})*100where: N : number of recent infections
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where: Ninc: number of recent infectionsNneg: number of HIV seronegatives
Results: HIV prevalence* in 2006, by sentinel group
14.014.0
16.0
8.0
10.0
12.0
erce
nt
0.92.0
4.0
6.0Pe
0.0
FSW ANC**
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*Adjusted for results of quality control**Weighted for provincial population size
Results: HIV l f l kResults: HIV prevalence among female sex workers, by survey year
44.742.6
39.936.840
45
50
42 3 42 5 45.8
33.630.2
26.823.4
20.317 4
25
30
35
42.3 42.5 45.841.3 41.9
25.721.4
14
17.414.7
5
10
15
20
0
5
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
QC adjusted QC adjusted EPP smoothed
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QC-adjusted QC-adjusted, EPP smoothed
Results: HIV l * f l kResults: HIV prevalence* among female sex workers, by age group
43.540.4
34.2
41.340
45
50
34.2
29.9
24.8
32.2
24.1
20
25
30
35
Per
cent
14.419.7
7.85
10
15
20P
2.90
5
1998 1999 2000 2001 2002 2003 2004 2005 2006
20 ld d ld <20 ld
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20 years old and older <20 years old
*Adjusted for results of quality control
Results: HIV l * f l kResults: HIV prevalence* among female sex workers, by survey year and duration of sex work
30.8
37.3
34.635
40
26.9
22.1
34.6
22.920
25
30
rcen
t
18.6
9.2 10.310
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Per
0
5
< 1 Year 1-2 Years > 2 Years
2002 2003 2006
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2002 2003 2006
*Adjusted for results of quality control
Results: HIV l * f l kResults: HIV prevalence* among female sex workers, by age and duration of sex work
16.0
14
16
18
10.8
8
10
12
Per
cent
2.8 2.9
2
4
6
P
06 months or less More than 6 months
Duration of work
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Aged <20 yrs old Aged 20 yrs or more
*Adjusted for results of quality control
Results: HIV prevalence* among FSWs byResults: HIV prevalence among FSWs, by province
12 6
20.6
25.8
30.726.7
20.7
20.4Odd M h
Siem ReapBattambang
Koh KongKampong Speu
SihanoukvilleBanteay Meanchey
10 5
11.1
11.5
12.612.5
11.3
11.1Pailin
Preah VihearKampong Cham
Phnom PenhStung Treng
Kampong ChhnangOddar Meanchey
rovi
nce
5.3
9.1
10.1
10.510.4
10.0
5.6Rattanakiri
KampotKratie
Svay RiengKampong Thom
PursatPailinPr
4.2
5.34.4
3.1
0 5 10 15 20 25 30 35
KandalTakeo
Prey Veng
S
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HIV Seroprevalence Percent
*Adjusted for results of quality control
Results: HIV prevalence among ANC, by survey year
3.0
3.5
1.92.1 2.1 2.1 2.0 1.8 1.6
1.5 1.3 1 1
1.51 5
2.0
2.5
1.82.5
2.9
1.92.4 2.2
0.9
1.3 1.1
0.5
1.0
1.5
0.01996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
QC adjusted weighted QC adjusted weighted and EPP smoothed
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QC-adjusted, weighted QC-adjusted, weighted, and EPP smoothed
Results: T d i ti t d HIV l *Results: Trends in estimated HIV prevalence* among ANC women, by ANC location
2.62.8 2.8 2.7
2.52.32.5
3.0
1.5
2.1 2.11.9
1.71.4
1.82.0 2.0 2.0 1.9
1 71.5
1.92.1 2.1 2.1
2.0
1.51 3
1.61.8
1 5
2.0
2.5
cent
1.4
1.8 1.71.6
1.41.2
1.11.0
1.0 1.11.3
0 5
1.0
1.5
Perc
0.0
0.5
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
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Urban Rural Total
* QC-adjusted, weighted, and smoothed with EPP
Result: Estimated HIV prevalence* amongResult: Estimated HIV prevalence* among general population aged 15-49 years old3 0
2.32.5
2.62.4
2.12.02 0
2.5
3.0
1.8 1.81.6
1.41.2
1.11.51.7
1.91.7
1.5 1 5 1.11.2
1.41.51.6
1.92.0
1.91.7
1.21.5
2.0
Perc
ent
1.1
1.51.3
1.21.1
0.90.8
0.91.0
0.5
1.0
P
0.01995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
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Urban Rural Total
*Qc adjusted, weighted and EPP smoothed
Results: HIV prevalence* among ANC byResults: HIV prevalence among ANC, by province
0 7
0.5
0.5
0.20.2
0.5
0.6Si R
Preah VihearStung Treng
KratieSvay Rieng
RattanaakiriOddar Meanchey
0 8
0.7
0.7
0.70.7
0.7
0.7Kampong Cham
PursatKandalTakeo
Kampong SpeuKampong Thom
Siem Reap
rovi
nce
1.5
1
0.8
0.80.8
0.9
1.3Battambang
Bantey MeancheyKg_Chhnang
KampotPhnom Penh
Prey VengKampong ChamPr
1.71.6
2.1
0.0 0.5 1.0 1.5 2.0 2.5
PailinSihanoukville
Koh kong
HIV S l P t
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HIV Seroprevalence Percent
*Adjusted for results of quality control
Estimating HIV incidence
Annualized period (365 days)
Assumed window period (155 days)
In HSS 2006:
I =({(365/155)Ninc}/{Nneg+[(365/155)Ninc]/2})*100
In HSS 2006: All new infection was assumed to occur within 155 day of the cohort if ll ti i tall participants were
followed up Annualized HIV incidence (HIV incidence among 100 person per year)
22Adjusted annualized incidence
Results: HIV incidence* among FSWs inResults: HIV incidence* among FSWs in 2006
2.552.5
3
1.681.5
2
rce
nt
0.801
Pe
r
0
0.5
Without
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Ajustment methods* With 95% confidence interval
Results: HIV incidence* among FSWs byResults: HIV incidence* among FSWs, by survey year
10.2
10
12
7.4
6.0
8
ent
4
6
Per
ce
1.7
0
2
1999 2000 2001 2002 2003 2004 2005 2006
24*Uncorrected incidence
1999 2000 2001 2002 2003 2004 2005 2006
Results: HIV incidence* among ANC womenResults: HIV incidence* among ANC women in 2006, by adjustment method
0 35
0.29
0.25
0.30
0.35
0.170.15
0.20
0.25
Per
cent
0.07 0.060.06
0.12 0.11
0.05
0.10
0.02 0.020.00
No adjustment Hargrove McDougalAjustment methods
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* With 95% confidence interval
Results: HIV incidence* among ANCResults: HIV incidence among ANC women, by survey year
0.9
0 70.8
0.9
1.0
0.6
0.7
0.5
0.6
0.7
erce
nt
0.170.2
0.3
0.4Pe
0.0
0.1
1999 2000 2001 2002 2003 2004 2005 2006
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* Unadjusted incidence
Results: Projected new HIV infectionResults: Projected new HIV infection among adult population aged 15+
700700
800
540
550
480
410360
630
400
500
600
mbe
r
420
330
270230
360
300260
200
300
400
Num
230200
0
100
2006 2007 2008 2009 2010 2011 2012
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Women Men
ConclusionsHIV l h d li d b h i l fHIV prevalence has declined among both sentinel groups of female sex workers and pregnant women attending antenatal clinicsData* suggest that some female sex workers may already be ata suggest t at so e e a e se o e s ay a eady beinfected with HIV when they start sex work or become infected almost immediately after startingHIV prevalence among pregnant women who attend provincial capital/urban ANCs has been consistently higher than amongcapital/urban ANCs has been consistently higher than among those who attend remaining district/rural ANCsHIV incidence has declined among both sentinel groups and it is estimated that among 100,000 pregnant women, 70 were newly infected in 2006infected in 2006.Although unadjusted HIV incidence among FSWs and ANCs is probably an over-estimate of true incidence, the declining trend and magnitude of the decline is consistent with prevalence data
28*9% HIV prevalence among FSWs who had reported working for less than one year
RecommendationsI t t t ti f t i f ti i t ll f tIntegrate testing for recent infection into all future rounds of HSSMaintain or improve adherence to quality assurance and capacity building for surveillance at provincial levelContinue to use dried blood spot specimens in future HSS rounds because of simplicity in preparing,HSS rounds because of simplicity in preparing, processing and storingMaintain current interventions among most at risk populations—despite declining prevalence and incidencepopulations—despite declining prevalence and incidence among both sentinel groups, this step will be crucial in preventing further spread of HIV and another wave of the epidemic
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the epidemic
Acknowledgementsl f / l• National Center for HIV/AIDS, Dermatology
and STDs (NCHADS)P i i l H lth D t t d P i i l• Provincial Health Department and Provincial AIDS ProgramsNational Institute of Public Health (NIPH)• National Institute of Public Health (NIPH)
• Collaborating partners:US CDC Gl b l AIDS P• US CDC Global AIDS Program
• USAID/PRASIT• World Health Organization
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• World Health Organization
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