Rapid Serological Tests Ineffectively Screen for HIV Exposure in HIV-Positive Infants

Brittany Urick, BA; Youyi Fong, PhD; Christopher Okiira, BSc; Nicolette Nabukeera-Barungi, MD; Denis Nansera, MD; Emmanuel Ochola, MD; Julius Nteziyaremye, MD; Victor Bigira, MD; Isaac Ssewanyana, BSc; Peter Olupot-Olupot, MD; Trevor Peter, PhD; Anisa Ghadrshenas, BSc; Lara Vojnov, PhD; Charles Kiyaga, BSc

Disclosures

J Acquir Immune Defic Syndr. 2018;77(3):331-336. 

In This Article

Results

A total of 3000 infants were enrolled at non-PMTCT facility entry points (46% female) (Table 1). Approximately half of the infants included were aged 8 months or younger (49%), and 70% of infants were aged 12 months or younger. The median age at study inclusion was 9 months (interquartile range: 4–14 months). In the HIV-positive study population, 35% of infants were aged 8 months or younger, and 51% were aged 12 months or younger. The median age at study inclusion for HIV-positive infants was 12 months (interquartile range: 6–17 months). Most (78%) infants were breastfeeding at the time of testing; however, less than half (43%) of the HIV-positive infants were breastfeeding at the time of testing. Fifty-eight percent of infants had attended a health care facility at some point within the previous year for any health care services including immunization in all study groups.

Ninety-four HIV-positive infants and children were identified at the non-PMTCT facility entry points combined. Infants presenting to the PMTCT entry point did not receive a serological screen because their exposure status was already known, and thus were not included in the analyses. One infant was excluded because of an error in the nucleic acid–based early infant test that could not be repeated resulting in a total of 2999 infants with both rapid serological and nucleic acid–based test results. The sensitivity of the rapid serological test to accurately detect HIV exposure was 61.7% (95% CI: 51.1 to 71.5), whereas the specificity was 97.3% (95% CI: 96.6 to 97.8) (Table 2). The positive predictive value in this population was 42.3% (95% CI: 34.0 to 51.1). Of the 137 infants with a positive rapid serological test, 79 (57.7%) were HIV negative by nucleic acid–based testing. The negative predictive value in this population was 98.7% (95% CI: 98.3 to 99.1). Of the 2862 infants with a negative rapid serological test, 36 (1.3%) were HIV positive by nucleic acid–based testing. In addition, 58% (79 of 137) infants with a positive rapid serological test were negative by nucleic acid–based testing.

We next analyzed the sensitivity of rapid serological tests to detect HIV exposure across several age ranges (Table 3). The sensitivity remained less than 50% in infants aged younger than 1 year. The sensitivity increased to approximately 75%–85% between the ages of 12–24 months. Similarly, the positive predictive value of rapid serological tests was below 35% in infants aged younger than 8 months and increased to above 90% only at 1 year of age.

The median age of HIV-positive infants with a negative rapid serological test was 8.5 months, whereas the median age of HIV-positive infants with a positive rapid serological test was 14 months (Figure 1) (Wilcoxon P-value = 0.0067). Although HIV-positive infants with a negative rapid serological test were significantly younger than HIV-positive infants with a positive rapid serological test, over a third (36.1%) of rapid serological test–negative, HIV-positive infants were aged 1 year or older. Furthermore, 38% of rapid serological test–positive, HIV-positive infants were aged 1 year or younger. Finally, there were no significant differences between HIV-positive infants with a positive rapid serological test and negative rapid serological test when comparing sex, breastfeeding status, or facility attendance.

Figure 1.

Comparison of age by all and rapid serological test outcome among HIV-positive infants. RDT, rapid diagnostic test.

Finally, although it was expected that most rapid serological test–negative, HIV-positive infants would have been from entry points providing care to sick infants,[6,7] several were identified in healthy populations (Table 4). A third (25 of 80) of HIV-positive infants who presented to health care facilities sick (nutrition and inpatient entry points) had a negative rapid serological test. Twenty-five percent of HIV-positive infants tested at the nutrition entry point were negative by rapid serological test (15 of 59), whereas 48% of HIV-positive infants tested at the inpatient entry points were negative by rapid serological test (10 of 21). Interestingly, 100% of HIV-positive infants tested at the outreach and immunization entry points were negative by rapid serological test (3 of 3). Last, 73% of HIV-positive infants tested at the outpatient entry point were negative by rapid serological test (8 of 11).

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