Adults: Body mass index for adults cannot be calculated if components necessary for its calculation (weight or height) is unknown or has not been collected (i.e. is coded to 888.8 or 999.9). BMI for adults is categorised according to the range it falls within as indicated by codes 1.1, 1.2, 2.1, 2.2, 3.1, 3.2, 3.3 or 9. For consistency, when the sample includes children and adolescents, adults can be analysed under the broader categories of 1, 2, 3 or 9 as used for categorising children and adolescents. Children/adolescents: Body mass index for children and adolescents aged 2 to 17 years cannot be calculated if components necessary for its calculation (date of birth, sex, weight or height) is unknown or has not been collected (i.e. is coded to 888.8, 999.9 or 9). Self-reported or parentally reported height and weight for children and adolescents should be used cautiously if at all. To determine overweight and obesity in children and adolescents, compare the derived BMI against those recorded for the relevant age and sex of the subject to be classified, against Table 1: Classification of BMI for children and adolescents, based on BMI cut-points developed by Cole et al (2000). For example, an 11 year old boy with a BMI of 21 would be considered overweight (i.e. coded as 2), or a 7 year old girl with a BMI of 17.5 would be considered not overweight or obese (i.e. coded as 1). Using this method, children and adolescents can only be coded as 1, 2, 3 or 9. |