Underwood B A
Bull World Health Organ. 1978;56(4):525-41.
Hypovitaminosis A is considered to be the most common cause of blindness in the developing countries but it is not possible to estimate the prevalence of keratomalacia directly attributable to it. Subclinical hypovitaminosis A is not measurable at present in human subjects, but studies in animals indicate that the possibility of subclinical effects should not be ignored. The recommended procedure for identifying the "at risk" population involves a three-part survey to evaluate dietary intake, biochemical indices, and clinical signs. This article examines all three approaches in some detail, but in the present state of knowledge, none of them gives a satisfactory estimate of vitamin A status. For community assessment, the article discusses preliminary experience with a predictive model of the number of children in a population at risk of hypovitaminosis A that is based on associations noted repeatedly between protein-energy malnutrition and certain child-rearing practices, family economics, and morbidity. Criteria have been established for deciding on the need for a programme of prevention and the types of programme most appropriate in different situations are discussed. The methods of programme evaluation must take into account the stated objectives of the programme.
维生素A缺乏症被认为是发展中国家失明的最常见原因，但无法直接估计由此导致的角膜软化症的患病率。目前在人体中无法检测亚临床维生素A缺乏症，但动物研究表明，亚临床影响的可能性不应被忽视。识别“高危”人群的推荐程序包括三部分调查，以评估饮食摄入量、生化指标和临床体征。本文详细研究了所有这三种方法，但就目前的知识水平而言，它们都无法对维生素A状况给出令人满意的估计。对于社区评估，本文讨论了基于蛋白质-能量营养不良与某些育儿习惯、家庭经济状况和发病率之间反复观察到的关联而建立的预测人群中亚临床维生素A缺乏症高危儿童数量的预测模型的初步经验。已经制定了决定预防计划必要性的标准，并讨论了在不同情况下最适合的计划类型。计划评估方法必须考虑计划的既定目标。
