Triangulation of Routine Antenatal HIV Prevalence Data and Adjusted HIV Estimates in Mozambique

Abstract

Background: Routine health system data are central to monitoring HIV trends. In Mozambique, the reported number of women receiving antenatal care (ANC) and antiretroviral therapy for prevention of mother-to-child transmission (PMTCT) has exceeded the Spectrum-estimated number of pregnant women since 2017. In some provinces, reported HIV prevalence in pregnant women has declined faster than epidemiologically plausible. We hypothesized that these issues are linked and caused by programmatic overenumeration of HIV-negative pregnant women at ANC.

Methods: We triangulated program-reported ANC client numbers with survey-based fertility estimates and facility birth data adjusted for the proportion of facility births. We used survey-reported ANC attendance to produce adjusted time series of HIV prevalence in pregnant women, adjusted for hypothesized program double counting. We calibrated the Spectrum HIV estimation models to adjusted HIV prevalence data to produce adjusted adult and pediatric HIV estimates.

Results: ANC client numbers were not consistent with facility birth data or modeled population estimates indicating ANC data quality issues in all provinces. Adjusted provincial ANC HIV prevalence in 2021 was median 45% [interquartile range 35%-52% or 2.3 percentage points (interquartile range 2.5-3.5)] higher than reported HIV prevalence. In 2021, calibrating to adjusted antenatal HIV prevalence lowered PMTCT coverage to less than 100% in most provinces and increased the modeled number of new child infections by 35%. The adjusted results better reconciled adult and pediatric antiretroviral treatment coverage and antenatal HIV prevalence with regional fertility estimates.

Conclusions: Adjusting HIV prevalence in pregnant women using nationally representative household survey data on ANC attendance produced estimates more consistent with surveillance data. The number of children living with HIV in Mozambique has been substantially underestimated because of biased routine ANC prevalence. Renewed focus on HIV surveillance among pregnant women would improve PMTCT coverage and pediatric HIV estimates.

FIGURE 1.

A, Provincial estimates of ANC and PMTCT coverage from 2015 to 2021 colored by region. B, Provincial estimates of HIV prevalence in pregnant women from 2013 to 2021 colored by region.

FIGURE 2.

Comparison of reported antenatal clinic (ANC) clients [dark blue], raw [green dashed] and adjusted [orange solid] number of live births at health facilities (brought forward in time by 5 months to align approximately with the timing of first ANC visits), and modeled estimates for the number of births from Spectrum (light blue). Smoothed trends shown as bold lines, with raw data as transparent points and lines.

FIGURE 3.

Estimates of adult HIV prevalence (left), HIV prevalence in pregnant women (middle left), adult ART coverage (middle right), and adult HIV incidence (right) in Cabo Delgado, Inhambane, Gaza, and Maputo. Models were calibrated to nationally representative household survey data and unadjusted ANC-RT HIV prevalence data (green points and line), adjusted ANC-RT data (orange points and line), and no ANC-RT data (blue points and line). Modeled indicator estimates are represented by lines without points. INSIDA 2009 and 2015 IMASIDA survey estimates of ART coverage and HIV prevalence used in calibration are represented by black points with uncertainty, and withheld INSIDA 2021 survey estimates are represented by gray points.

FIGURE 4.

Validation analysis against withheld 2021 INSIDA data by ANC-RT model scenario. A, Absolute difference and (B) relative difference between provincial INSIDA 2021 survey estimate and 2021 estimates of HIV prevalence and ART coverage by ANC-RT model scenario. Points are sized relative to the provincial HIV-positive population. The dotted line represents no difference between modeled estimate and INSIDA 2021 survey, and the solid black lines are the median difference by model scenario.

FIGURE 5.

Vertical transmission and pediatric estimates by ANC-RT prevalence scenario. A, Prevention of mother-to-child transmission (PMTCT) coverage. B, Mother-to-child transmission (MTCT) rate. C, Vertical new child HIV infections. D and E, Comparison of Mozambique provincial adult female and pediatric ART coverage versus all other sub-Saharan African countries.