Rapid oral HIV test during labour is feasible, acceptable, and accurate

The use of rapid oral HIV tests during labour in previously untested women is feasible and acceptable, according to a US study published in the July 15^th edition of the Journal of the American Medical Association. The study also established that the rapid oral HIV test used during the study has a high degree of accuracy. The investigators argue that their findings have important implications for the prevention of mother-to-baby transmission of HIV not only for the US, but also in resource limited countries where women of unknown HIV status are often seen by healthcare providers for the first time during labour.

In November 2002 US regulatory authorities approved the Ora-Quick rapid oral HIV test, which is able to provide results within 20 minutes. Investigators from the MIRIAD (Mother-Infant Rapid Intervention at Delivery) study wished to see how feasible and acceptable it would be to for delivery staff to offer the Ora-Quick rapid HIV tests to women in labour and how accurate the results of rapid tests were.

A total of 16 hospitals in six US cities participated in the study. Women in labour who had not been previously tested for HIV were offered HIV counselling and both a rapid oral HIV test as well as a traditional HIV antibody test using a blood sample. If the oral test result proved positive women and their infants were provided with prophylactic antiretrovirals to prevent the mother-to-baby transmission of HIV.

A total of 7321 women were eligible for rapid HIV testing during the study period (November 2001-November 2003). Just over a fifth of women (22%) were not offered a rapid HIV test as there was either no staff member available or because the rapid oral HIV test had not yet received approval. Of the remaining 5744 women, 4849 (84%) provided consent and underwent counselling and rapid HIV testing.

Thirty-four women tested HIV-positive using both the rapid oral and blood tests. There were four false positives, but no false negatives, using the rapid oral test. All four women who had a false positive test were given prophylactic antiretrovirals during labour, which was discontinued once doctors were informed that the oral test had yielded a false positive result.

Sensitivity of the oral test was 100% and specificity was 99.9%. The oral test had a positive predictive value of 100% and a negative predictive value of 90%.

Rapid HIV testing during labour was associated with younger age (under 30 years), black or Hispanic ethnicity, less than 32 weeks of pregnancy, and no prenatal care.

Admission to hospital between 4pm and midnight was associated with lower rapid HIV test acceptance, with acceptance lowest on Friday nights.

Rapid test results were delivered within a median of 66 minutes, compared to a median of 28 hours for HIV antibody blood tests.

The factor most strongly associated with a failure to deliver rapid test results during labour was the duration of delivery. Women who arrived at hospital two hours or less before delivery were most likely to receive their rapid test results after delivery.

Of the 34 women diagnosed with HIV during delivery, 27 were in active labour when they first arrived at hospital. A total of 18 women received antiretroviral medication to prevent mother-to-baby transmission of HIV. The remaining nine women were not provided with anti-HIV drugs because they arrived at hospital too close to the time of delivery and could not receive their rapid HIV test result in time to be given prophylactic therapy.

AZT was started in pregnant women a median of 33 minutes after the return of the rapid test result, and anti-HIV medication was provided to infants exposed to HIV a median of 3.8 hours after birth.

Seventeen of the 32 women had a vaginal delivery and 15 had a caesarean. Three infants were infected with HIV, two of which were born using a vaginal delivery.

Of the 34 women testing HIV-positive, 30 were black, of whom nine were migrants from Africa or the Caribbean.

“We found that rapid HIV testing yielded accurate and timely results in women in labour and that implementing rapid testing was acceptable and feasible,” write the investigators.

The US CDC recommends opt-out HIV testing for pregnant women using rapid oral testing. The UK has had a policy of opt-out HIV testing for pregnant women for a number of years. A recent audit of the management of pregnancy in HIV-positive women in the UK conducted by the British HIV Association found that 99.8% of woman had their HIV diagnosed before delivery. To read the aidsmap.com news story click here.

The MIRIAD investigators comment, “rapid HIV testing during labour is cost-saving to the medical system. Our study demonstrated that, in general, results are timely and that antiretroviral prophylaxis can be provided promptly to HIV-infected women and their infants.”

They conclude, “the MIRIAD findings are important in both the United States and internationally. In many settings, including in the developing world, pregnant women with unknown HIV status are often seen by clinicians for the first time during labour. Rapid testing during labour can enable pregnant women with undocumented HIV status to learn their HIV infection status so they can receive antiretroviral prophylaxis and be referred for comprehensive medical care and follow-up.”