Validity of self-reported receipt of iron supplements during pregnancy: implications for coverage measurement

Abstract Background Iron-deficiency anemia during pregnancy is an underlying cause of maternal deaths, and reducing risk through routine iron supplementation is a key component of antenatal care (ANC) programs in most low- and middle income countries. Supplementation coverage during pregnancy is estimated from maternal self-reports in population-based household surveys, yet recall bias and social desirability bias lead to errors of unknown magnitude. Methods We linked data from household and health facility surveys from 16 countries to estimate input-adjusted coverage of iron supplementation during pregnancy. We assessed the validity of reported receipt of iron supplements in client exit interviews using direct observation as the gold standard across 9 countries with a recent Service Provision Assessment (SPA). Using a sample of 227 women who participated in the Nepal Oil Massage Study (NOMS), we also assessed the validity of self-reported receipt of iron folic acid (IFA) supplements. We used Poisson regression models to explore the association between client and health facility characteristics and agreement of self-reported receipt of iron supplements compared to direct observation. Results Across the 16 countries, iron supplements were in supply at most of the 9215 sampled health facilities offering ANC services (91%). We estimated that between 48 and 93% of women attended at least one ANC visit at a health facility with iron supplements available. The specificity of recall of receipt of iron supplementation immediately following a visit was 79.3% and the sensitivity was 88.7% for the entire sample. Individual-level accuracy was high (Area under the curve > 0.7) and population bias low (0.75 < inflation factor < 1.25) across all countries. By contrast, in the NOMS sub-study, the accuracy of self-reported receipt of IFA supplements after 1–2 years was poor (sensitivity 86.1%, specificity 34.3%). Adjusted regression analyses indicated that older age and higher level of education were associated with poorer agreement between self-reports and direct observation. Conclusions These findings suggest the need for caution when using self-reported measures with an extended recall period. Further validation studies using conditions similar to widely used population-based household surveys are warranted