March 1990

Growth Velocity Values Measured During Short Observation Periods May Obscure Effects of Treatment of Growth Failure

Author Affiliations

Department of Pediatrics Mayo Clinic 200 First St Rochester, MN 55905

Am J Dis Child. 1990;144(3):267-268. doi:10.1001/archpedi.1990.02150270013007

Sir.—Growth velocity charts are often used to indicate changes in growth rates over short periods. Eager investigators have a special nurse make a number of measurements in children with growth failure, using a stadiometer every 2 to 3 months after treatment with a hormone, a vitamin, or a special diet, perhaps given by a feeding tube, has been initiated. These measurements are then extrapolated and used with growth velocity standards such as those published by Tanner and Davies.1

The problem rests with the length of the interval between measurements. Let us assume that they are obtained every 3 months. Growth velocity data are published in centimeters per year. The investigator simply multiplies the result by 4. This also multiplies observer bias and measurement error by 4. Here is a hypothetical example. The measurements in the tabulation below were obtained during a year in which a child would grow

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