Antenatal care surveillance for monitoring malaria prevalence and intervention coverage: a multicountry analysis

Estimates of malaria prevalence and intervention coverage in Africa are primarily based on nationally representative household (HH) surveys. However, the expense and infrequency limit the utility of HH surveys for operational action by malaria programmes. We assessed whether data collected during first antenatal care (ANC1) visits, consisting of data on malaria prevalence using rapid diagnostic tests, ownership of insecticide-treated nets (ITNs) and treatment-seeking for children with fever, could provide relevant data to guide decision-makers. Malaria prevalence among ANC1 attendees in select areas of six countries (Benin, Burkina Faso, Mozambique, Nigeria, Tanzania and Zambia) was compared with prevalence data among children under 5 and school-aged children from cross-sectional HH surveys in the same areas. To examine the relationship between prevalence among ANC1 attendees and children, we fitted a linear trend to the log-OR of the risk of testing positive. The predictive performance of the model was assessed by leave-one-out cross-validation (LOOCV). District-level ANC1 prevalence and prevalence among children are correlated (Spearman's rank correlation, r=0.79, 95% CI=0.65 to 0.88, p<0.001) and ANC1 prevalence is predictive of prevalence among children (LOOCV mean absolute error=6.5%). To understand whether data on ITN ownership collected at ANC1 are representative of ownership in the underlying communities, we assessed the district-level proportion of HH ownership in five countries (Benin, Burkina Faso, Mozambique, Nigeria and Zambia) and fitted an ordinal regression model to the ranking of ownership by district. Reported rates of treatment-seeking for children under 5 with fever, testing for malaria and treatment for the HH and ANC1 settings were compared. Estimates of malaria prevalence and ITN coverage derived from ANC1 attendees correlate well with HH survey estimates and may be useful in monitoring malaria prevalence and prevention efforts. In contrast, data on treatment-seeking does not appear useful.