## Growth Tracking in Severely Obese or Underweight Children

Report on experience using a body-mass index chart that may be better suited for plotting children at the extremes of the growth spectrum. This growth chart uses a “modified z score,” proposed by the CDC, which expresses variations from the median in terms of a unit equal to one half the difference between 0 and +2 z scores (for measures above the mean) and one half the difference between 0 and -2 z scores (for measures below the mean) for any given age and gender.

If one uses modified z score as the y-axis against age, ordinary BMI changes fall along a curve that is much close to a straight line, so outliers should be easier to spot in this circumstance.

Authors illustrate the advantages of using an age-vs-BMI chart with modified z-score isobars over the standard CDC 2000 charts and over the modified charts showing the percentage of the 95th percentile of BMI.

Chambers 2017 (*Pediatrics*) | PubMed 29114063 | Author Search