Transcript Scenarios for future demand for ART methods and Assumptions (UNAIDS and WHO working group) ppt, 207kb

Scenarios for Future Demand for ART
Methods and Assumptions
UNAIDS/WHO Working Group
Overview

HIV prevalence projections

Estimating numbers needing ART

Scenario assumptions for scale up
Classification of HIV Epidemics

Low-level: no identifiable group has prevalence >5%

Concentrated: “transmission not sustained outside core
groups”: prevalence among pregnant women below 1%
in urban areas, but some groups at high risk have
prevalence >5%

Generalised: “transmission sustained outside core
groups”: prevalence among pregnant women
consistently over 1%
HIV Prevalence Projections

Generalized epidemics: HIV prevalence trend
based on ANC surveillance, assumed stable
epidemics into the future

Concentrated and Low-level epidemics:
– Estimated size of groups at risk
– Estimated current prevalence based on recent
surveillance data
– Projections based on assumptions of HIV prevalence
saturations in high-risk groups
Number newly needing ART

The number newly needing ART in each year is
assumed to be the number of people who would
die within 2 years without ART
– Proxy for the WHO guideline – CD4 count below 200

This will depend on the incidence of HIV some
years previously (corresponding to the time of
infection)
– From 2006-2010, this is mostly determined by HIV
incidence that has already taken place
Total number needing ART
Total number needing ART = Number newly
needing + Number of survivors from the
previous year (including those receiving ART)

The number receiving ART therefore
accumulates in future years

Need in future years depends on the number
receiving treatment in previous years
– Scenarios are dominated by scale up assumptions
Low Scenario Assumptions

Baseline coverage was calculated for each
country from the most recent ‘3 by 5’ report
– Percentage of those in need who actually receive
ART

Coverage is then assumed to increase in a
linear way in every country, to reach a level of
60% in the year 2012.
– Scale up is therefore faster in countries with a lower
starting point
High Scenario Assumptions

The baseline is the unmet need, and the rate at which it
decreases, as observed in the most recent ‘3 by 5’
reports

The percentage of unmet need is assumed to decrease
in a linear way in every country until coverage reaches
85%
– Uses observed rates of decrease of the most urgent unmet need
(1 yr from death) from previous years, by country
– Coverage increases in a non-linear way
– Scale up assumes steadily increasing coverage for new cases
Total ARV Coverage in Low and Middle Income Countries (% of need)
80%
HIGH
70%
60%
50%
LOW
40%
30%
20%
10%
0%
2005
2006
2007
2008
2009
2010
Total Number Receiving ARV in Low and Middle Income Countries
10,000,000
HIGH
9,000,000
8,000,000
7,000,000
6,000,000
5,000,000
LOW
4,000,000
3,000,000
2,000,000
1,000,000
0
2005
2006
2007
2008
2009
2010