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Published byWilfrid Ward Modified over 9 years ago
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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
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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
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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)
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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
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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?
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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
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Identify maternal HIV antibody in Infant Thanks to E. Abram and N. Rollins
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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 1 st immunization coverage >80% – The 1 st immunization coverage 70% - 80% special sample size and sub-study will be required to adjust for findings
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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)
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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
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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 positive (HIV-infected infant) HIV DNA PCR negative (HIV uninfected infant) HIV Ab Negative (HIV-unexposed infant) HIV Ab Negative (HIV-unexposed infant) HIV Ab positive (HIV-exposed infant) HIV Ab positive (HIV-exposed infant) Standard of care recommended by WHO
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Consent and interview process caregivers 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
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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
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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
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