Nutrition Research Group at Instituto de Medicina Integral Prof Fernando Figueira - IMIP, Rua dos Coelhos, 300, Boa Vista, Recife, PE CEP: 50,070-550, Brazil.
BMC Pregnancy Childbirth. 2013 Jan 16;13:13. doi: 10.1186/1471-2393-13-13.
Pregnancy anemia remains as a public health problem, since the official reports in the 70's. To guide the treatment of iron-deficiency anemia in pregnancy, the haemoglobin concentration is the most used test in spite of its low accuracy, and serum ferritin is the most reliable test, although its cutoff point remains an issue.
METHODS/DESIGN: The aim of this protocol is to verify the accuracy of erythrocyte indices and serum ferritin (studied tests) for the diagnosis of functional iron-deficiency in pregnancy using the iron-therapy responsiveness as the gold-standard. This is an ongoing phase III accuracy study initiated in August 2011 and to be concluded in April 2013. The subjects are anemic pregnant women (haemoglobin concentration < 11.0 g/dL) attended at a low-risk prenatal care center in the Northeast of Brazil. The sample size (n 278) was calculated to estimate sensitivity of 90% and 80% of specificity with relative error of 10% and power of 95%. This study has a prospective design with a before-after intervention of 80 mg of daily oral iron during 90 days and will be analyzed as a delayed-type cross-sectional study. Women at the second trimester of pregnancy are being evaluated with clinical and laboratorial examinations at the enrollment and monthly. The 'responsiveness to therapeutic test with oral iron' (gold-standard) was defined to an increase of at least 0.55 Z-score in haemoglobin after 4 weeks of treatment and a total dose of 1200 mg of iron. At the study conclusion, sensitivities, specificities, predictive values, likelihood ratios and areas under the ROC (Receiver Operating Characteristic) curves of serum ferritin and erythrocyte indices (red blood cell count, haematocrit, haemoglobin concentration, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, red blood cell distribution width, reticulocyte count) will be tested. The compliance and adverse effects are considered confounding variables, since they are the main obstacles for the iron-therapy responsiveness.
This study protocol shows a new approach on iron-deficiency anemia in pregnancy from a functional point of view that could bring some insights about the diagnostic misclassifications arising from the dynamic physiologic changes during the gestational cycle.
WHO International Clinical Trials Registry Platform U1111-1123-2605.
自 70 年代官方报告以来，妊娠贫血仍然是一个公共卫生问题。为了指导妊娠缺铁性贫血的治疗，尽管血红蛋白浓度检测准确性较低，但仍将其作为最常用的检测方法，而血清铁蛋白是最可靠的检测方法，尽管其临界点仍然存在问题。
方法/设计：本方案的目的是使用铁治疗反应作为金标准，验证红细胞指数和血清铁蛋白（研究测试）在诊断妊娠功能性缺铁中的准确性。这是一项正在进行的 III 期准确性研究，于 2011 年 8 月启动，将于 2013 年 4 月结束。研究对象为在巴西东北部低风险产前保健中心就诊的贫血孕妇（血红蛋白浓度<11.0 g/dL）。根据相对误差为 10%和 95%的功率，计算出 278 例样本量（n），以估计 90%和 80%的灵敏度和特异性。本研究采用前瞻性设计，在 90 天内每天口服 80mg 铁进行干预前后，并将作为延迟型横截面研究进行分析。在妊娠中期，对孕妇进行临床和实验室检查，并在入组时和每月进行评估。“口服铁治疗试验反应”（金标准）定义为治疗 4 周后血红蛋白至少增加 0.55 Z 评分，总铁剂量为 1200mg。在研究结束时，将测试血清铁蛋白和红细胞指数（红细胞计数、血细胞比容、血红蛋白浓度、平均红细胞体积、平均红细胞血红蛋白、平均红细胞血红蛋白浓度、红细胞分布宽度、网织红细胞计数）的敏感性、特异性、预测值、似然比和 ROC（接收者操作特征）曲线下面积。依从性和不良反应被认为是混杂因素，因为它们是铁治疗反应的主要障碍。
本研究方案从功能角度展示了妊娠缺铁性贫血的新方法，这可能为妊娠周期中生理变化带来的诊断错误分类提供一些见解。
WHO 国际临床试验注册平台 U1111-1123-2605。
