Measuring Effectiveness of PMTCT Programs

Transcription

1 Measuring Effectiveness of PMTCT Programs Sandi McCoy, MPH, PhD University of California, Berkeley July 16, 2011 Enhancing Implementa/on Science: Program Planning, Scale- up, and Evalua/on

2 WHO s Four Prong PMTCT Strategy Component 1 Component 2 Component 3 Component 4 PrevenAon of HIV in women, especially young women PrevenAon of unintended pregnancies in HIV- infected women PrevenAon of transmission from an HIV infected woman to her infant Support for HIV infected women, their infant, and family

3 PMTCT Cascade All women presenang for delivery HIV infected women only (A) A=end antenatal care (B) Be offered HIV Test (C) Accept HIV Test (D) Obtain HIV Test Results (E) Agree to ARV prophylaxis (F) Adhere to ARV prophylaxis (G) Adhere to infant ARV doses INFECTIONS AVERTED Stringer EM, Chi BH, Chintu N, et al. Monitoring effecaveness of programmes to prevent mother- to- child HIV transmission in lower- income countries. Bull World Health Organ. 2008;86(1):57-62.

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5 PMTCT Evaluation Challenges PMTCT programs widely implemented Significant variability of programs Long follow- up periods Facility- based evaluaaons may be biased Ethical problems with following mother- infant pairs and linking to PMTCT services A\riAon a significant problem

6 So how do we measure impact on: Perinatal transmission Postnatal transmission, and 12- month HIV- free survival?

7 A common approach: Program Coverage Counts the number of mother- infant pairs in a populaaon receiving PMTCT services Assumes benefit of PMTCT intervenaon (from efficacy trials) can be applied to populaaon Why might program coverage not be a good method for impact evaluaaon? (but good for process and outcome evaluaaon)

8 Figure 2. Cascade of Events Negotiated by Mothers Infected With Human Immunodeficiency Virus (HIV) and Their HIV-Exposed Infants to Prevent Mother-to-Child HIV Transmission 91% 96% 94% 94% 81% Stringer, E. M. et al. JAMA 2010;304: Copyright restrictions may apply.

9 Figure 2. Cascade of Events Negotiated by Mothers Infected With Human Immunodeficiency Virus (HIV) and Their HIV-Exposed Infants to Prevent Mother-to-Child HIV Transmission Of 3196 HIV- exposed infants, 1845 (58%) had NVP detected 91% 96% 94% 94% 81% Stringer, E. M. et al. JAMA 2010;304: Copyright restrictions may apply.

10 A common approach: MTCT at a single point in time Using facility registers, count the number of HIV- exposed infants in a calendar year that are HIV- posiave at 4-6 weeks

11 Single measurement of impact Early Transmission Rate WHO Guidelines What are some problems with this approach? Legend: IntervenAon group Before Program Aaer Program Time Source: Mead Over, Center for Global Development.

12 Single measurement of impact Early Transmission Rate ??? 2010 WHO Guidelines Legend: IntervenAon group Before Program Aaer Program Time Source: Mead Over, Center for Global Development.

13 Group activity Consider various methods to evaluate the effecaveness of PMTCT programs Evaluate strengths and weaknesses of each approach ~15 minutes

14 Immunization Clinic Survey Visit infant immunizaaon clinics or immunizaaon campaign events and conduct HIV DNA PCR on HIV- exposed infants at their first immunizaaon visit (e.g., DTP1). Repeat two years later and compare the number of infected & exposed infants.

15 Immunization Clinic Survey Counterfactual: Baseline measurement (pre- post) Strengths: Can be representaave if vaccine coverage high Convenient Weaknesses: Depends on vaccine coverage >90% Facility based Misses late postnatal infecaons (breaskeeding) Can be expensive

16 Importance of Comparison Groups Early Transmission Rate Legend: IntervenAon group Control group Before Program Aaer Program Time Source: Mead Over, Center for Global Development.

17 Importance of Comparison Groups 0.15 Early Transmission Rate EsAmated Impact Legend: IntervenAon group Control group Before Program Aaer Program Time Source: Mead Over.

18 Retrospective Cohort IdenAfy HIV+ women who accessed services at ANC clinics in the last year. Link to infant records and, if necessary, follow- up and test infant for HIV (DNA PCR). Compare transmission rate across Ame.

19 A common approach: Cohort Studies (prospective) PMTCT PMTCT PMTCT ANC Booking Delivery 24 months

20 A common approach: Cohort Studies (retrospective) PMTCT PMTCT PMTCT ANC Booking Deliveries to HIV+ mothers 24 months

21 Retrospective Cohort Counterfactual: Baseline (first measurement) Strengths: Can examine individual- level quesaons Efficient (start with HIV+ women) Weaknesses: Need to track down infant outcomes or link to infant data (expense) Loss to follow- up Facility based

22 Household Surveys Visit a representaave sample of households (e.g., DHS) and test all infants <2 years to measure exposure to HIV and HIV infecaon. Ask mothers about infant deaths. Repeat and compare the number of infected & exposed infants and HIV- free survival.

23 Household Surveys Counterfactual: Baseline (first measurement) Strengths: NaAonally representaave (DHS) Efficient (piggy- back on other survey) Can examine HIV- free 12 month survival Weaknesses: Large survey size Maybe only pracacal in high- prevalence countries

24 Routine Early Infant Diagnosis (EID) Data Examine rouane EID data (at 4-6 weeks) over Ame to determine the EID posiavity rate.

25 Routine Early Infant Diagnosis (EID) Data Counterfactual: Baseline measurement Strengths: Trend data Available surveillance data Weaknesses: Validity depends on EID coverage Facility- based

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