Department of Fundamental Nutrition, Nutrition School, Federal University of the State of Rio de Janeiro, Rio de Janeiro, Brazil.
Department of Social Nutrition, Nutrition Institute, Rio de Janeiro State University, Rio de Janeiro, Brazil.
J Nutr. 2021 Oct 1;151(10):3197-3204. doi: 10.1093/jn/nxab226.
Vitamin A deficiency (VAD) and anemia are the most prevalent nutritional deficiency in children globally. The dried blood spot (DBS) method has been used in prevalence studies of VAD and anemia in different age groups. However, it has not yet been validated for children.
This study aimed to assess the reproducibility and validity of DBS in the diagnosis of VAD and anemia in preschoolers.
Venous and capillary blood samples were collected from a representative sample of children <5 y old who attended the public health system in Rio de Janeiro. Serum retinol and hemoglobin were measured in 235 and 182 children, respectively. Serum retinol was measured with HPLC and hemoglobin was measured with spectrophotometry in samples of venous (gold standard) and capillary blood (test method, DBS). DBS reproducibility was assessed with the intraclass correlation coefficient (ICC), κ, and prevalence-adjusted and bias-adjusted κ (PABAK). DBS validity was assessed with sensitivity, specificity, accuracy index (AI), positive predictive value (PPV), and negative predictive value (NPV).
DBS showed very good reproducibility for serum retinol (ICC = 0.94, κ = 0.83, PABAK = 0.76) and very good/good reproducibility for hemoglobin (ICC = 0.86, κ = 0.69, PABAK = 0.69). Prevalence rates for VAD by the reference and test methods were 11.5% and 11.9%, respectively, whereas the anemia rates were 19.2% and 46.2%. The test method showed low sensitivity (33%) and PPV (32%) and high specificity (91%) and NPV (92%) for serum retinol. For hemoglobin, the test method showed fair sensitivity (71%), low PPV (30%), fair specificity (60%), and high NPV (90%). AI was 83% for VAD and 62% for anemia.
The results suggest that DBS is adequate for the diagnosis of VAD in preschool children, but not for anemia.
维生素 A 缺乏症（VAD）和贫血是全球儿童中最普遍的营养缺乏症。干血斑（DBS）法已用于不同年龄组 VAD 和贫血的患病率研究。然而，它尚未在儿童中得到验证。
本研究旨在评估 DBS 在学龄前儿童 VAD 和贫血诊断中的再现性和有效性。
从参加里约热内卢公共卫生系统的代表性 5 岁以下儿童中采集静脉和毛细血管血样。分别在 235 名和 182 名儿童中测量血清视黄醇和血红蛋白。使用高效液相色谱法（HPLC）测量血清视黄醇，使用分光光度法测量静脉血样（金标准）和毛细血管血样（测试方法，DBS）中的血红蛋白。使用组内相关系数（ICC）、κ、校正后偏倚 κ（PABAK）评估 DBS 再现性。使用灵敏度、特异性、准确性指数（AI）、阳性预测值（PPV）和阴性预测值（NPV）评估 DBS 有效性。
DBS 对血清视黄醇的再现性非常好（ICC=0.94，κ=0.83，PABAK=0.76），对血红蛋白的再现性也很好/好（ICC=0.86，κ=0.69，PABAK=0.69）。参考方法和测试方法的 VAD 患病率分别为 11.5%和 11.9%，贫血患病率分别为 19.2%和 46.2%。测试方法对血清视黄醇的灵敏度（33%）和 PPV（32%）较低，特异性（91%）和 NPV（92%）较高。对于血红蛋白，测试方法的灵敏度（71%）、PPV（30%）、特异性（60%）和 NPV（90%）均较低。VAD 的 AI 为 83%，贫血的 AI 为 62%。
结果表明，DBS 可用于诊断学龄前儿童的 VAD，但不能用于贫血。
