Discussion. Definition of Impact Analytic issues surrounding impact measures

Transcription

1 Methodological challenges of Measuring HIV Specific Impacts For Design Considerations for Evaluating the Impact of PEPFAR IOM Workshop April 30 - May 1, 2007 Theresa Diaz, MD, MPH Centers for Disease Control and Prevention Global AIDS Program The findings and conclusions in this presentation are those of the author and do not necessarily represent the views of the Centers for Disease Control and Prevention

2 Discussion Definition of Impact Analytic issues surrounding impact measures Incidence and prevalence trends Infections averted Mortality rates Orphans averted Attribution

3 HIV Impact Measures Reduction in the number of persons infected by HIV Improved survival of persons with HIV infection Improved quality of life and productivity of citizens directly or indirectly affected by HIV

4 General Conceptual Framework for Monitoring AIDS Impacts Inputs Inputs Prevention Outputs Care/Support/Treatment Outputs Non-program Effects Program Outcome (Behaviors) Program Outcome (service use/ coverage) Impacts HIV infection Morbidity Mortality Orphans Social Economic

5 HIV prevalence trends: Challenges Currently based on HIV ANC sentinel surveillance Pregnant women Urban concentration Clinics used may change overtime Concentrated epidemics (e.g. Vietnam) can not rely on ANC sentinel surveillance for trends Lack of decline in HIV prevalence can be due to multiple factors (e.g. increased survival, immigration)

6 HIV prevalence trends: Solutions Developed methods to analyze trends from ANC Use only consistent sites Use most recent two or three years data Compare results from different methods (Chisquare linear, trend, Linear regression, Nonparametric methods) Second population based survey with HIV testing Collect data on ARV use in these surveys Standardizing methods for collection of HIV seroprevalence in high risk groups (e.g. RDS)

7 HIV incidence: Challenges Chronic infection, symptoms do not appear till years after infection Gold standard cohort studies which are costly Cohorts may not reflect true population incidence Laboratory assays - overestimation Multiple models exist national estimate

8 HIV incidence: Solutions Laboratory assays: Adjustment formula being further validated a second assay is under development for a potential two test algorithm Exclude persons on ARV Developing models based on population based surveys provide age and sex specific incidence May provide geographic incidence depending upon sample size

9 Infections Averted: Challenges Measuring a non event Originally thought using a model based on effectiveness of different interventions Agreed to not include studies from developed world Used standardized criteria to review studies GAPs in information on certain interventions Strong personal opinion of a few individuals Uncomfortable about having empty cells

10 Infections Averted: Solutions BUCEN model (UNAIDS reference group reviewed) Baseline estimates of numbers of new cases for years using data for years pre- PEPFAR (<2005) Final estimates for years will be based on using actual data from 2005 through Number of infections prevented = difference between the baseline estimates and the final estimates Issues Data may not be available until after 2010 Not able to inform decisions on prevention.

11 Averting infections in newborns Calculation without preventive ARVs approximately 35% transmission rate with preventive ARVs approximately 16% Difference = 19% 533,700 pregnancies received preventive ARVs X 19% = 101,500 newborn infections averted Factors not accounted for Breast feeding practices Efficacy differences among countries and programs Adherence or proper use of ARVs Counseling potential impact in preventing new HIV infections in HIV negative women

12 Mortality rates: Challenges Among HIV infected population Counting "lives saved" is not the best outcome measure when looking at impact of ARTs since treatment may only delay death by a year or two. Calculating survival from ART clinics is challenging especially due to lost to followup

13 Mortality rates: Challenges Among general population Cause of death difficult to ascertain Calculating lives saved due to infections averted assumes: Persons would not have died of the infection before dying of other causes Persons do not become infected at a later time. Years of life added among HIV infected Does this decrease other mortality (e.g. adding years of life to a mother increases survival of children?) Could this increase chance of transmission thus increasing mortality of others?

14 Mortality rates: Solutions HIV infected Years of life added is one measure that may be more appropriate Aggressively seek out information on those lost to follow-up Collect information on deaths from hospital records in a standardized way

15 Mortality rates: Solutions General population Verbal Autopsies Accept a certain level of uncertainty of cause of death Concentrate on trends in young adults Exclude accidents, suicides and death due to childbirth Modeling will need to take into account multiple factors Examine difference in the overall number of deaths in a time period with and without ART.

16 Averting Orphans: Challenges Single orphans versus double orphans While extending the life of an HIV infected orphan through ART is a desired outcome, this would actually add to years of orphanhood.

17 Averting Orphans: Solutions Use years of orphanhood averted because ARTs may only delay the death of a parent by a few years Could calculate number of children who manage to reach age 18 before the death of a parent whose life is extended by ARTs Examine difference in the overall number of orphans in a time period with and without ART

18 Important Considerations Enable countries to perform impact analyses Disseminate suggested methods Technical assistance Trainings/workshops One on one mentoring Work with other donors, implementers etc. Work with the GF impact evaluation activity

19 Attribution 1 Essentially can not disentangle specific donor, NGO or government programs So instead should describe the contribution of donors, NGOs and government

20 Attribution 2 We do want to know the effect of types of programs and their coverage on impact measures, e.g. What level of ART coverage decreases general mortality? What type of prevention activity in what populations decreases HIV incidence? How to best do this is where our major challenge lies

21 GAP Acknowledgements Meade Morgan Laura Porter Keith Sabin BUCEN Tim Fowler OGAC Michelle Sherlock

22 Thank you!