Screening HIV positive pregnant women for TB in South Africa increased detection by 10-fold

Universal TB screening of all HIV positive pregnant women increased case detection and was associated with reduced early infant mortality in a South African study presented at IAS 2017.

TB is a leading cause of maternal and infant morbidity and mortality in HIV positive pregnant women. Currently-recommended symptom-based screening of HIV positive pregnant women may not be sensitive enough.

Investigators from the Perinatal HIV Research Unit, University of the Witwatersrand and Johns Hopkins University, Baltimore conducted a cluster-randomised trial to compare universal sputum TB testing with standard symptom-based testing in this population.

The trial was conducted across 16 public-sector antenatal clinics in two health districts that were randomised to either strategy. HIV positive pregnant women without currently diagnosed TB were eligible.

In universal testing clinics, all women were asked to produce a sputum sample. In symptom clinics, only those with WHO criteria for TB testing (cough, fever, night sweats, or weight loss) were asked to.

Samples were tested using Xpert MTB/RIF. Halfway through the study liquid MGIT culture was added. Follow up of women and infants was two months postpartum.

During the study period (May 2015 to March 2017), 941 and 1100 HIV positive pregnant women were enrolled in the universal and symptom clinics, respectively. In both arms, median age was approximately 30 years, median gestational age 25 weeks, 8% had TB before, 99% were on ART, and CD4 count was 440 cells/mm³.

In universal and symptom clinics, respectively, 34/941 and 4/1100 women were diagnosed with TB during pregnancy. Universal clinics prevalence 3.6% (95% CI: 1.2 to 6.0) and symptom clinics 0.36% (95% CI: 0.0 to 1.1), p=0.01.

At two months post-partum, infant mortality in universal clinics was 1% compared with 2.2% in symptom clinics, p=0.134. Maternal death was 0.1% compared with 0.3%, respectively. Miscarriages and stillbirths were similar in both arms.

MGIT culture identified more TB than Xpert: 5.1% were MGIT positive compared with 1.4% Xpert positive, p<0.05.

The investigators concluded that universal TB screening of all HIV positive pregnant women increased case detection 10-fold and halved early infant and maternal deaths (but this was not statistically significant). Xpert detected one third the rate of TB compared with MGIT.

Martinson N et al. Universal sputum testing vs symptom-based testing for tuberculosis (TB) in HIV infected pregnant women: a cluster-randomised implementation trial in South Africa. 9th IAS Conference on HIV Science. 23–26 July 2017. Paris. Poster abstract TUPDB0204LB.
http://programme.ias2017.org/Abstract/Abstract/5746 (abstract)