The information included in the WHO Global Database on BMI complies with the following format:
- Systematic use of international BMI cut-off points to classify adult nutrition status;
- Display of the whole spectrum of adult nutritional status, as measured by the proportion within each BMI category;
- Display of mean and standard deviation of BMI;
- Disaggregation of prevalence rates and mean and standard deviation of BMI according to sex, age, urban/rural strata and location.
The required criteria for entering survey data in the database are:
- A clearly defined population-based sampling frame, permitting inferences to be drawn about an entire population;
- A probabilistic sampling procedure involving at least 100 adults (allowing for an estimation of prevalence with a 95% confidential interval);
- Use of appropriate equipment and standard measurement techniques1,2;
- Presentation of age standardized results, where possible;
- For those surveys where results are presented using a different BMI classification system, the principal investigators are contacted and encouraged to re-analyze their data sets following the WHO recommended procedure for reporting BMI data, or otherwise, to provide the raw data to the WHO Department of Nutrition for Health and Development (NHD) for re-analysis. Survey results are systematically checked for inconsistencies and these are brought to the attention of the investigators, with a request for clarification. A hard copy of the survey documentation, together with any corrigendum or additional information received from the authors is filed under the survey reference number. All source information is clearly cited on the website. The aim is to keep the database as fully documented and comprehensive as possible, so that queries concerning compiled data can be answered accurately.