Q + A on India’s revised AIDS estimates

[Guest guest]

Q + A on India's revised AIDS estimates

1. Why were the estimates revised downwards?

India has greatly expanded and improved its surveillance system in

recent years, and increased the population groups covered. More data sources

were considered, including special studies and behavioural surveillance, as well

as the national survey NFHS-3 which for the first time included a component on

HIV.

Revised methodology was also used which has enabled India to

produce more accurate estimates of its epidemic.

This improvement in the way that India collects and analyses its

HIV data has enabled a much better understanding of India's AIDS epidemic and

has shown that the number of people living with HIV is lower than previous

estimates indicated.

2. Why is it such a big difference?

When you look at the data previously available for India you will

see that the range was particularly broad (3.4-9.4 million). This indicates a

high level of uncertainty around the numbers of people living with HIV in India.

India's epidemic is complex due to the vastness of the country, the large

numbers of people living in India (over 1 billion) and the difference in HIV

prevalence in different states and in urban and rural areas. Because of this

uncertainty around previous estimates, the Indian government, together with

national and international partners, invested a lot of effort into obtaining

more accurate

information about its epidemic and has widely increased numbers and

groups of people surveyed.

This work has resulted in much more accurate information about

India's epidemic––which is reflected in the new estimates and much smaller

ranges are expected.

3. What is UNAIDS role in this work?

In December 2006 the UNAIDS Reference Group on Estimates, Modelling

and Projections issued recommendations for improving estimates using data from

population-based surveys in concentrated epidemics.

As early as March 2007, as soon as early results of NFHS-3 became

available, UNAIDS supported NACO to set up a Core Technical Working Group on

Estimates and Projections. In the first week of June 2007, as soon as all

sentinel surveillance data for 2006 became available, the UNAIDS Secretariat,

WHO and NACO organized a meeting of national and international experts to

discuss the detailed methodology to estimate HIV prevalence and related

indicators.

Estimates for previous years were then revised based on the new set

of data. Epidemiological experts on AIDS in India, as well as key

international experts have been involved in this effort.

4. What is the NFHS-3 survey?

The NFHS-3 (National Family Health Survey 3) survey is a large

population based survey (or household survey) which was conducted in India in

2005- 2006.

The survey involved essentially going into villages and towns,

going into households and surveying people present in the household on that day.

The survey represents an entirely new source of HIV data for India

as it is the first time that it has included an HIV component.

The sample size for HIV was over 100,000 people.

This type of survey has been conducted in many countries in Africa

where it has been the basis for improving estimates.

5. What is sentinel surveillance?

Sentinel surveillance was introduced in many parts of the world in

the early 90's, but the sentinel system in India didn't get started until 1998.

Sentinel surveillance are warning systems, they take settings where blood tests

are being carried out, from women attending ante-natal clinics for example, and

every one month or two

months in a year, they test everyone who comes into that clinic.

India has in recent years expanded its sentinel surveillance system

to extend its geographical coverage and also to include groups at higher risk of

HIV infection such as people who inject drugs, men who have sex with men and

commercial sex workers. So India's system has improved in recent years in terms

of measuring the country's HIV prevalence.

6. What methodology was used?

The methodology involved several steps to make use of all available

data sources.

Estimates of HIV prevalence among adults (aged 15-49) were generated for 2006

for all states in India using the latest population census data in the UNAIDS

recommended WORKBOOK estimation tool.

- WORKBOOK is a spreadsheet used to estimate and project adult HIV

prevalence from surveillance data in countries with low level or

concentrated epidemics. Estimates are based on prevalence in

populations with high risk behaviours and populations at low risk, as

well as estimates of the size of populations with high risk behaviours.

The adult HIV prevalence for each state was initially based on the

adult HIV prevalence observed in the National Family Health Survey 3 (NFHS-3).

The NFHS-3 generated state-specific HIV prevalence estimates for Andhra Pradesh,

Karnataka, Maharashtra, Manipur, Tamil Nadu, and Uttar Pradesh. Using

urban/rural and male/female prevalence ratios, HIV prevalence was estimated for

adult women and men in urban and rural areas. For states that did not have a

state-specific NFHS-3 estimate, the NFHS-3 estimate for the rest of India was

combined with the antenatal clinic prevalence of the specific state to inform

the HIV prevalence among adults in those states;

HIV infections occurring among groups at higher risk of HIV

infection, who may have been missed by the household survey, were then added to

the above HIV prevalence estimates. In low prevalence states, these groups will

account for a larger proportion of all people living with HIV compared to states

with high prevalence. The number of people in groups at higher risk in each

state was based on a combination of the estimates of the size of these groups,

based on

consensus estimates used in the Integrated Biological and Behavioural

Assessment data, combined with HIV prevalence data from the sentinel

surveillance system;

Ranges of uncertainty were calculated around the estimated point

prevalence among adults in 2006, based on the combined information from the

NFHS- 3 and the groups at higher risk of HIV infection;

HIV prevalence data from consistent antenatal clinic surveillance

sites over time was examined to assess the trend in HIV prevalence over time for

each state, between 2001 and 2006;

The trend over time in prevalence between 2001 and 2006, together

with the point prevalence estimate for 2006, and an assessment of the start date

of the epidemic, were then used to generate smoothed epidemic curves of HIV

prevalence over time since the start of the epidemic for each state, using the

WORKBOOK projection feature;

Combining the trend in adult HIV prevalence over time with

programmatic information about antiretroviral treatment and programmes for

preventing mother to child transmission of HIV, the Spectrum software was used

to estimate for each year since the start of the epidemic, the number of adults

and children living with HIV, the number of new HIV infections, the number of

people in need of

antiretroviral treatment, the number of AIDS-related deaths, and

other indicators.

Ranges of uncertainty were then calculated around these estimated

indicators.

- SPECTRUM is a suite of policy models. Each model includes a detailed

user manual that not only describes how to use the software but also

includes sections on data sources, interpreting and using the

results, a tutorial, and a description of the methodology.

7. What does this new data tell us?

The new data tells us that India's epidemic, although still large

in numbers, is smaller than previous estimates indicated.

It does show some signs of a decline in HIV prevalence among sex

workers in areas where focused interventions have been implemented, particularly

in the southern states although overall prevalence levels among this group

continues to be high.

It also indicates that there is a slow decrease in HIV prevalence

among the general population in southern states. Although more analysis is

required this probably means that the number of people becoming infected with

HIV is decreasing. This decrease is more perceptible in states such as Tamil

Nadu where the intensity of HIV prevention efforts has been high.

8. Will less money be needed now for the AIDS response in India?

Not necessarily. India will use the new data that has become

available to best inform its HIV programming. This will mean evaluating its

resource needs estimates, prevention needs and treatment needs. What it will

mean is that India will be better able to focus its HIV programming to where it

will be most effective

and making sure the money works.

9. How does this affect the rest of the world?

According to the 2006 AIDS Epidemic Update report, the estimated

number of people living with HIV in 2006 was 39.5 million people.

The new data and analysis for India shows that the total number of

people living with HIV would be lower, although still well within the range

around the global estimate for 2006 (range 34.1-47.1 million).

Other indicators (numbers newly infected, number of deaths, number

needing treatment) are likely to be affected and UNAIDS will, as it does every

year, reestimate the global epidemic in light of all new data sources available,

which will be published in the AIDS epidemic update in November 2007.

Contact: Sophie Barton-Knott | UNAIDS Geneva | +41 22 791 1697 |

bartonknotts@...

www.unaids.org