India's HIV prevalence has been 'grossly overestimated'

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India's HIV prevalence has been 'grossly overestimated'

India's HIV prevalence rates have been grossly overestimated and

require substantial downwards revision, according to a late-breaker

presentation at the Sixteenth International Conference in Toronto on

Thursday August 17th. Population-based HIV prevalence estimates in

Andhra Pradesh, the south Indian state thought to have the highest

prevalence of HIV, were found to be two-and-half times lower than

estimates based on sentinel screening at antenatal and sexual health

clinics.

At the end of 2005, India's National AIDS Control Organisation

(NACO) estimated that there were 5.21 million people living with

HIV, although this figure had been criticised by some as an

underestimate.

Indeed, UNAIDS estimated that the number of people living with HIV

in India at the end of 2005 was closer to 5.7 million - higher than

South Africa's estimated 5.5 million - although it suggested a lower

and upper range of 3.4 million and 9.4 million, respectively.

NACO extrapolates data from the public health system – primarily

women testing for HIV during antenatal care, as well as anonymous

surveillance from sexual health clinics – in order to estimate HIV

prevalence in India, and until now no population-based study had

systematically examined the validity of this extrapolation.

Investigators from the Administrative Staff College of India and the

Institute of Medical Sciences in Hyderabad sampled 13,838 adults

aged 15-49 from 66 rural and urban clusters that represented the 4.5

million adults in the Guntur district of south India's Andhra

Pradesh state, which is thought to have the highest HIV prevalence

in India.

Demographic data were obtained from a total of 12,617 individuals

(91.2% of those sampled), and dried blood spots obtained at the same

time were tested for HIV antibodies, p24 antigen and HIV RNA. The

results were then compared with the HIV estimates from NACO's

sentinel surveillance data.

The investigators found that the adjusted HIV rate in adults was

1.72% (95% CI, 1.35-2.09%), with a slightly higher prevalence in men

(1.74%; 95% CI, 1.27-2.21%) than women (1.70%; 95% CI, 1.36-2.04%).

Prevalence was higher in urban settings (1.89%; 955 CI, 1.39-2.39%)

compared with rural settings (1.64%, 95% CI, 1.10-2.18%).

Using a standard of living index (SLI), the investigators found that

HIV prevalence rates were twice as high in people who were in the

lower half of the SLI (i.e. poorer), compared with those in the

upper half (2.58% vs 1.20%, respectively).

Around 23% of pregnant women had accessed antenatal care through the

public health system in the previous two years. Significantly, they

discovered that very poor women were over-represented, which

resulted in an unusually high HIV prevalence rate (3.61% versus

1.08% of pregnant women who did not use the public health system).

This would have skewed the surveillance-based data which found

antenatal clinic HIV prevalence to be 3%.

The investigators calculated that their population-based estimate

for the Guntur district is 45,925 adults after adjusting for

underrepresented high-risk groups. In contrast, NACO's surveillance-

based estimate was 112,635 adults. In other words, population-based

HIV prevalence was two-and-a-half times lower than the sentinel

surveillance data.

By applying the investigator's population-based estimates to the

entire state of Andhra Pradesh, this results in a reduction from

1.44 million adults living with HIV to just over half a million.

Lalit Dandona, of the Centre for Human Development in Hyderabad,

presenting, concluded that NACO's method for estimating HIV

prevalence grossly overestimates HIV in all south Indian states –

home to around three-quarters of India' HIV-positive population –

and which have a similar pattern of public health system use by the

poorest people. Therefore, NACO's current HIV estimate of 5.21

million for India should be revised downwards by a substantial

amount.

Reference

Dandona L et al. A population-based study suggests that the HIV

estimate for India needs major revision. Sixteenth International

AIDS Conference, Toronto, abstract ThLB0107, 2006.

________________

Anand Bairagi

E-mail: <amitissw@...>