WHO Estimates of Vitamin and Mineral Deficiencies: Methodological approaches to calculate global and regional prevalences and address uncertainty of the estimates
WHO/CDC Technical Consultation
7-9 December, 2010, Atlanta, GA, USA
In the 1992 World Health Assembly, Member States were urged to "establish, as part of the health and nutrition monitoring system, a micronutrient monitoring and evaluation system capable of assessing the magnitude and distribution of vitamin A and iron deficiency disorders and monitor the implementation and impact of control programmes". As this request has not been fulfilled by all Member States, the World Health Organization (WHO) produces global estimates of vitamin and mineral deficiencies to identify high-priority areas to target and implement micronutrient interventions; to advocate for resource allocation; and to assess the influence of vitamin and mineral deficiencies as risk factors to the overall global burden of disease.
The WHO Vitamin and Mineral Nutrition Information System (VMNIS) currently collates information at the national, regional, state or local level on anaemia, vitamin A and iodine deficiencies of populations. Based on this information, the Micronutrients Unit has published global estimates of the prevalence of anaemia (1993-2005), vitamin A deficiency (1995-2005), and iodine deficiency (1993-2003 and 2004-2007). The collated data, along with data from other WHO databases, has also been used by the WHO Mortality Burden of Disease study to assess the comparative importance of iron, zinc and vitamin A deficiencies in causing premature death, loss of health and disability in different populations.
Multiple approaches have been used to estimate the global burden of vitamin and mineral deficiencies, sometimes with low predictive accuracy. The various methods used are the result of the different purposes of the estimates; sparse data for priority target groups; timing of data collection; geographical distribution of the data; underlying assumptions; and low quality data sources. The inconsistency of the methods and estimates generated has frequently confused Member States and other stakeholders.
In order to develop a common approach to develop global estimates of vitamin and mineral deficiencies, the Departments of Nutrition for Health and Development and the Mortality and Burden of Disease Unit, WHO, and the International Micronutrient Malnutrition Prevention and Control Program (IMMPaCt), US Centers for Disease Control and Prevention are convening a technical consultation.
Objectives of the technical consultation (Atlanta, 7-9 December 2010):
- Review various methodological approaches and assumptions used in estimating vitamin and mineral deficiencies globally;
- Review available sources of data, taking into account their strengths and limitations;
- Review and discuss statistics used to address precision and accuracy of the estimates;
- Reach consensus on methods to estimate global vitamin and mineral deficiencies, and trends by micronutrient and subpopulations;
- Discuss the use of estimates for calculating the global burden of disease.
WHO would like to thank the US Centers for Disease Control and Prevention (CDC) for their financial support.