Voluntary counselling and testing: no effect on HIV incidence in rural Zimbabwe

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People who underwent voluntary counselling and testing for HIV in rural Manicaland, Zimbabwe had just the same rate of HIV infection as people who weren’t tested during the following three years, and those who tested HIV-negative were more likely to engage in risky behaviours compared to their untested counterparts, the Third South African AIDS Conference heard today in Durban.

Voluntary counselling and testing (VCT) have been described as the cornerstone of HIV prevention by international agencies such as UNAIDS and the World Health Organization, yet the evidence showing that VCT contributes to behaviour change and reduced HIV incidence in developing countries is conflicting.

In 2005 for example, researchers published a study of the impact of VCT in Uganda which found no effect on behaviour or incidence of knowledge of HIV status between individuals who chose to receive the results of population seroprevalence testing with counselling offered to households in a district of Uganda and those who did not receive their results. Indeed, individuals who had not previously undergone HIV testing were less likely to request the results, as were unmarried persons and HIV-positive individuals (Matovu 2005).

Glossary

VCT

Short for voluntary counselling and testing.

person years

In a study “100 person years of follow-up” could mean that information was collected on 100 people for one year, or on 50 people for two years each, or on ten people over ten years. In practice, each person’s duration of follow-up is likely to be different.

risky behaviour

In HIV, refers to any behaviour or action that increases an individual’s probability of acquiring or transmitting HIV, such as having unprotected sex, having multiple partners or sharing drug injection equipment.

sample

Studies aim to give information that will be applicable to a large group of people (e.g. adults with diagnosed HIV in the UK). Because it is impractical to conduct a study with such a large group, only a sub-group (a sample) takes part in a study. This isn’t a problem as long as the characteristics of the sample are similar to those of the wider group (e.g. in terms of age, gender, CD4 count and years since diagnosis).

statistical significance

Statistical tests are used to judge whether the results of a study could be due to chance and would not be confirmed if the study was repeated. If result is probably not due to chance, the results are ‘statistically significant’. 

The Zimbabwe study, carried out by Professor Lorraine Sherr and colleagues from the Royal Free and University College Medical School, London, compared baseline data gathered in the period 1998-2000 with findings from follow-up three years later.

The study carried out undisclosed HIV antibody testing on a sample of the population in Manicaland rural communities, and also offered voluntary counselling and testing to participants.

HIV antibody status was determined for 9454 individuals; prevalence was 20% in men and 26% in women at the first wave of sampling in 1998-2000.

Uptake of voluntary counselling and testing was modest, despite the fact that 88% of individuals wanted to know their HIV status. Only 6.6% of participants had already undergone HIV testing, and only 5.9% of participants availed themselves of pre-test counselling at a mobile VCT clinic during the follow-up period, and a total of 19% of the 5775 participants available for follow-up reported an HIV antibody test by that time.

However, when participants who reported an HIV antibody test were asked whether they had returned for the result, replies revealed a significant gap. While 19% of the participants had been tested, only 12% of men and 10% of women had returned to collect the result.

Only 51% reported that they had had pre-test counselling, despite the fact that pre-test counselling should have been routinely offered according to national guidelines, and men were somewhat less likely to recall pre-test counselling. “If you don’t recognise you’ve had it, it can’t be very good quality,” said Professor Sherr.

Individuals were asked about their sexual history and provided their replies in a confidential way so that they would not be embarrassed to reveal intimate details to an investigator. A total of 6,259 individuals provided information in this way.

At the time of follow-up, researchers discovered that individuals who had tested HIV-negative through VCT were significantly more likely to have engaged in risky behaviour than people who did not take an HIV test. Risky behaviour was measured by asking about concurrent sexual partnerships, condom use, the number of new sexual partners in the previous year and beer hall attendance.

However, women (but not men) who tested HIV-positive were significantly more likely to report condom use in the past two weeks after receiving a positive result.

HIV incidence did not differ between tested and untested groups – 22.5 new infections per 1000 person years of follow-up versus 17.5 new infections per 1,000 person years (the numerical difference was not statistically significant).

Demographic analysis showed that individuals with more education were more likely to test for HIV, and that perception of individual risk of HIV did not drive individuals to seek testing. Indeed, the most risk-averse individuals were most likely to test, said Professor Sherr.

Concluding her presentation, Professor Sherr said it would be important to minimise unanticipated impact - in particular an increase in risky sexual behaviour - as VCT is rolled out alongside antiretroviral treatment in southern Africa.

References

Sherr L et al. Voluntary HIV testing in rural Zimbabwe - what is the uptake, impact on sexual behaviour and HIV incidence 3 years later? Third South African AIDS Conference, Durban, abstract 46, 2007.

Matovu JKB et al. Voluntary HIV counselling and testing acceptance, sexual risk behaviour and HIV incidence in Rakai, Uganda. AIDS 2005, 19: 503-511.