Misdiagnosis of overweight and underweight children younger than 2 years of age due to length measurement bias.
BACKGROUND
Accurate determination of the length of very young children is important because weight-for-length standards are used to assess both under- and overweight. Clinical measurements of length, which usually involve a paper-and-pencil method, may often be inaccurate in children younger than 2 years.


OBJECTIVE
To compare length measured by the conventional clinical paper-and-pencil method with length measured by the research standard recumbent length-board method in a sample of children under 2 years of age.


METHODS
Research assistants measured 160 children 0 through 23 months of age using the recumbent length-board method, and clinical staff measured the same children using the paper-and-pencil method. To assess the relationship between the research and clinical length measurements, we used ordinary least squares regression.


RESULTS
We found a strong linear relationship between the 2 measures of length (R2 = 0.98). The paper-and-pencil method systematically overestimated length in children under 2 years of age. A fitted regression equation estimated that the research standard length was 95.3% of the clinical measurement plus 1.88 cm. Over the entire age span, the mean (SD) difference between clinical and research measurements was 1.3 (1.5) cm.


CONCLUSIONS
Using the paper-and-pencil method can lead to underestimates of overweight and exaggerated estimates of thinness. To improve the accuracy of length measurement, medical providers should use standardized procedures with a recumbent length board to measure children under 2 years of age, at least for children whose initial paper-and-pencil measurement of length puts them at one extreme or the other.
Rifas-Shiman
Sheryl L
SL
Department of Ambulatory Care and Prevention, Harvard Medical School and Harvard Pilgrim Health Care, Boston, Massachusetts, USA.
Rich-Edwards
Janet W
JW
Scanlon
Kelley S
KS
Kleinman
Ken P
KP
Gillman
Matthew W
MW
D000886:Anthropometry / Q000295:instrumentation / Q000379:methods*; D015982:Bias; D001827:Body Height; D003627:Data Interpretation, Statistical; D003951:Diagnostic Errors / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009765:Obesity / Q000175:diagnosis* / Q000453:epidemiology*; D010808:Physical Examination / Q000295:instrumentation / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013851:Thinness / Q000175:diagnosis* / Q000453:epidemiology*; D014481:United States / Q000453:epidemiology