Validity of patient-reported anemia and therapeutic use of iron supplements during pregnancy: 2015 Pelotas (Brazil) birth cohort

Abstract

This study aimed to investigate the validity of patient-reported anemia and therapeutic use of iron supplements, compared to hemoglobin values recorded on the patient's prenatal card. The study used data from the 2015 Pelotas (Brazil) birth cohort. For validation of self-reported anemia, we included all mothers with hemoglobin values recorded on their prenatal card (N = 3,419), while validation of self-reported therapeutic use of iron supplements included those who had hemoglobin values recorded on their prenatal care and who reported having used medicines containing ferrous sulfate during pregnancy. Anemia was defined as at least one record of hemoglobin ≤ 11g/dL on the prenatal card (gold standard). Prevalence of anemia according to the gold standard was 35.9% (34.3-37.5), while patient-reported anemia was 42.2% (40.8-43.7), and patient-reported therapeutic use of iron supplements was 43.2% (41.3-45.1). Sensitivity of patient-reported anemia was 75.2% (72.8-77.6) and specificity was 75.1% (73.3-76.9). For patient-reported therapeutic use of iron supplements, sensitivity was 66.4% (63.5-69.2) and specificity was 71.9% (69.7-74.0). Specificity of patient-reported anemia and patient-reported therapeutic use of iron supplements in mothers with ≥ 12 years of schooling was 78.4% (75.4-81.4) and 79.5% (76.1-82.9), respectively. In the study population, for every five postpartum women that reported anemia or therapeutic use of iron supplements, three were telling the truth. The specificity of both self-reports was high in mothers with ≥ 12 years of schooling.