ABSTRACT
The World Health Organization recommended in 1978 that the National Center for Health Statistics/Centers for Disease Control growth reference curves be used as an international growth reference. To permit the expression of growth in terms of standard deviations, CDC developed growth curves from the observed data that approximate normal distributions. Because of significant skewness, standard deviations for weight-for-age and weight-for-height were calculated separately for distributions below and above the median. Standard deviations below the median were calculated from the 5th, 10th, 25th, and 50th observed percentiles while those above the median were based on the 50th, 75th, 90th, and 95th observed percentiles. Height-for-age distributions did not show significant skewness, thus, the standard deviations were calculated based on all six of the above observed percentiles. The normalized reference curves provide a highly useful data base that permits the standardized comparison of anthropometric data from different populations.
PIP: The World Health Organization recommended in 1978 that the National Center for Health Statistics/Centers for Disease Control (CDC) growth reference curves be used as an international growth reference. To permit the expression of growth in terms of standard deviations, CDC developed growth curves from the observed data that approximate normal distributions. Because of significant skewness, standard deviations for weight-for-age and weight-for-height were calculated separately for distributions below and above the median. Standard deviations below the median were calculated from the 5th, 10th, 25th, and 50th observed percentiles while those above the median were based on the 50th, 75th, 90th, and 95th observed percentiles. Height-for-age distributions did not show significant skewness, thus, th standard deviations were calculated based on all 6 of the above observed percentiles. The normalized reference curves provide a highly useful data base that permits the standardized comparison of anthropometric data from different populations.
Subject(s)
Anthropometry/methods , Child Development , Age Factors , Anthropometry/history , Body Height , Body Weight , Child , Child, Preschool , Female , History, 20th Century , Humans , Male , Reference Values , United Kingdom , United States , World Health OrganizationABSTRACT
General medical and nutritional practice assumes that hemoglobin and hematocrit values are equally useful in detecting anemia and that they can be used interchangeably for anemia screening. These two tests, at presumed equivalent levels, identify varying prevalences of anemia in the same population. This study examines anemia prevalence rates using hemoglobin and hematocrit tests performed in seven separate surveys on a total of 13,040 children. These data indicate that hemoglobin and hematocrit screening tests are indeed not comparable in detecting anemia in the same population. Using only hematocrit tests, anemia is diagnosed in 1 to 10% of children with normal hemoglobin levels and is not detected in 20 to 50% of children who might be considered anemic on the basis of low hemoglobin levels.
