ias 2011, rome, july 17 - 20

Generic protocol for national population-based impact evaluation of national programs for

PMTCT at 6 weeks post-partum

Thu-Ha Dinh, MD., MS., US CDC/GAP

IAS 2011, Rome, July 17 - 20

Overview of Presentation• Background -- Justification of the evaluation• Evaluation questions • Primary objectives• Who – Where – How• Ethical consideration• Methods

• Design• Sample size• Testing algorithms

• Procedure• Data management – storage – analysis• Dissemination of findings

PMTCT effectiveness• HIV transmission – proximate purpose of

programs is to reduce MTCT of HIV• ARV prophylaxis • Safe feeding• Maternal ART

• HIV free survival – ultimate goal of programs is to save children from HIV & death

• Time points: – Perinatal and during breast-feeding (6 wks, 6

months, 9 months, 12 months, 18 months, etc)

Why do we need national population estimate?

• Overall effectiveness of the program• Assess mother-infant pairs in PMTCT and not

reached • Provide unbiased estimate of HIV-infected

infants/children

Primary Evaluation Question• What is population-based perinatal MTCT rate measured

at 6 weeks? What is the HIV exposure prevalence among infants at 6 weeks ? What is the HIV infection prevalence among infants, 6 weeks What is the coverage of each PMTCT service along PMTCT cascade?

How we measure HIV exposure prevalence?• Self-reported HIV positive status from mother?

– Self-report bias– HCT uptake

• Documented HIV positive status of mother during pregnancy?– Information documented – HCT uptake

• Identify maternal HIV antibody in targeted infant (biomedical marker) ? – No bias: self-report or HCT uptake or information doc.– Include HIV acquisition– Sensitivity and specificity of the antibody test used

0-1 m 1-2 m 2-6 m 6-9 m 9-12 m 12-18 m

Maternal HIV ABHIV DNAinf_HIV Ab

Blood sample of HIV-infected in-fant

Thanks to Elaine Abrams and Nigel Rollinsx

Identify maternal HIV antibody in Infant

HIV

Ab

test

Thanks to E. Abram and N. Rollins

Where we can recruit representative sample of the infant population?

• At labor and delivery clinic?– Home delivery?– HCT during ANC, L&D

• At home – household survey?• HCT during ANC, L&D– Not part of routine - expensive

• At immunization clinic?– The 1st immunization coverage >80%– The 1st immunization coverage 70% - 80% special

sample size and sub-study will be required to adjust for findings

Design an Evaluation

• Questions objectives variables needed• Who: inclusion and exclusion, age range (4-8, 6-8?)• Where: to recruit potential participants • Ethical consideration• Design

– Cross-sectional design point estimate (6 weeks)– Sampling frame:

• multistage (province, facility) select facilities• participants from each selected facility (potential participant

load systematic or random or consecutive)

Design: Sample size

• Estimate HIV prevalence in pregnant women• Estimate ARV uptake among HIV+ pregnant women• Estimate/collect existing MTCT • Specify the appropriate level of precision• Assume a design effect of 2 and double the

calculated sample size to take account of cluster sampling

Design: Procedure

Eligible caregiver-infants

Do consent to take part in the survey

Don't consent to take part in the survey

Caregiver interview and infant-DBS

Caregiver interview and no infant-DBS

HIV DNA PCR positive(HIV-infected infant)

HIV DNA PCR negative (HIV uninfected infant)

HIV Ab Negative(HIV-unexposed infant)

HIV Ab positive(HIV-exposed infant)

Standard of care recommended

by WHO

Consent and interview processcaregivers vs. mothers

Decision needs to be based on• Local situation all legal caregivers

– Orphan population – Proportion of mothers who work– Local child Act toward health care right/assess – Community consent acceptable ?

• Precision needed for estimate• Infant benefit vs. Mother benefit• Who should receive test result? ? validity of findings if caregivers excluded

Design: Data management/Storage/Analysis • Data management:

– Quality control: at facility and at survey office– Data entry and safety– Who can access to the data – Ownership of the data

• Storage:– Paper-based: when paper-based will be destroyed– Public domain: how and when

• Data analysis– Dummy tables key outcomes – Identify potential bias can be controlled by analysis

collect those variables

Dissemination of findings

• Provide feedback to clinics and provinces to improve/scale up program

• Provide feedback to provincial DOH and national MOH

• Share findings and lessons learned with other donors and organizations

• Publish findings on peer review journals