Lecture 10 - Evaluation of Anthropometric Data Flashcards
- used to interpret indiv and group measurements
Index (plural: indices)
- simple numerical ratio like the body mass index (BMI)
Index (plural: indices)
- constructed from two or more weight measurements (ex. weight-for-height)
Index (plural: indices)
- measurement compared against one’s age (ex. weight-for-age)
Index (plural: indices)
Commonly used growth indices in the Philippines
- weight-for-age
- length-for-age
- height-for-age
- weight-for-length
- weight-for- height
- general index of acute malnutrition or short-term rapid onset undernutrition
Weight-for-age
- widely used to assess PEM and overnutrition
Weight-for-age
- used for rapid screening
Weight-for-age
- low weight for age is described as ____ and reflects a pathological process called ______
lightness; underweight
Limitations for WFA
- requires accurate age information
- does not distinguish between acute and chronic malnutrition
- children with low weight for age are not necessarily underweight
- may classify children with poor linear growth as normal and edema may complicate its interpretation
indicate (index of) past or current nutritional status
LFA/ HFA
measure stunting
LFA/HFA
low height for age is described as ____ and reflects a pathological process called ______
shortness; stunting
a less sensitive indicator of current nut, status compared with weight-for-height
HFA/LFA
aside from WFA, also - dependent on accurate age info
HFA/LFA
- sensitive index of current nutritional status
WFH/WFL
- measure of wasting
WFH/WFL
low weight for height is described as ____ and reflects a pathological process called ____
thinness; wasting
Advantages of WFH/WFL (2)
- advantageous - can distinguish acute from chronic undernutrition
- advantageous: not age dependent
Systems for Expressing Indices (3)
- Z-score system
- Percentile system
- Percent of median system
measure of an indiv value with respect to the distribution to the ref. population
z-score
refers to the position of the measurement value in relation to the all the measurements for that reference population ranked in order of magnitude
percentile
- expresses measurements as a percentage of the median value of the expected reference
- Percent of median system
ratio of a measured anthro value in the indiv to the median value of the ref. data for the same age or height expressed as a percentage
- Percent of median system
most widely used system of expressing indices
Z-score system
Evaluation of indices (4)
- comparison with a ref. distribution/data
- comparison with predetermined reference limits
- comparison with cut-off points
- trigger levels
obtained from a healthy sample group
ref. distribution
- values expressed as percentiles, standard deviation scores, or percent of median
ref. distribution
- values set to classify individuals as having “unusually low,” “usual,” or “unusually high” measurements
Reference limits
- two reference limits usually defined (lower and upper limit and the interval between them is known as the reference interval)
Reference limits
- based on the relationship between nut. assessment indices and functional impairment and/or clinical signs of deficiency
Cut-off points
- used to establish the prevalence of malnutrition within a pop. or to identify and classify malnourished indiv.
Cut-off points
an _____ is a measurement or index and its associated ref. limit or cut-off point
indicator
- combined with cut-off points to set the level of an index or indicator or a combination of indices at which a public health problem exists of a specified level of concern
Trigger levels
set arbitrarily or may follow the local or international organizations if available
Trigger levels
Sources of reference data which is - compiled from measurements made on well-nourished healthy individuals selected from an elite group (they must be ethnically and genetically representative of the pop. being investigated)
local
Sources of reference data which is preferred when ethnic and genetic diff are considered less important than the influences of nutrition, infection, parasitic diseases, and environmental and economic factors
international
Use of reference data (4)
- comparisons across populations
- proportion of individuals with abnormal indices
- surveillance studies
- evaluate trends and effectiveness of intervention programs
- clinical setting
- to identify those at risk for malnutrition and to assess the response for treatment
- encompasses both stature and weight measurements compiled from cross-sectional sampling of normal healthy infants and children of varying ages
Distance growth reference data for infant and children
- developed using either of two approaches: descriptive or prescriptive
Distance growth reference data for infant and children
uses a representative sample of normal healthy children to generate a reference
descriptive
selects children who are well-nourished and healthy and who adhere to established feeding and healthcare recommendations to generate a standard
prescriptive
- a ____ tells us how children are growing while a _____ tell us how children should grow
reference; standard
- developed by FNRI and Philippine Pediatric Society (PPS) in 1985
- includes 26,691 Filipino children from birth to 19 y from almost all regions
FNRI-PPS reference data
major limitation of FNRI-PPS reference data
included malnourished children
- year 2000 - shifted to the use of this international standard
- collected mainly from large, nationally representative probability cross-sectional samples of children from birth to 18 y
- derived from four diff surveys (conducted from 1960s and 1970s in USA)
National Center for Health Statistics (NCHS)/WHO growth reference
major limitations of National Center for Health Statistics (NCHS)/WHO growth reference
inclusion of formula fed infants and twins
- derived from WHO Multicenter Growth Reference Study (MGRS) conducted bet. 1997 and 2003
- included 8440 breastfed infants and young children (<5 y) from diverse ethnic backgrounds and cultural settings in the US, Oman, Norway, Brazil, Ghana, and India
WHO multicenter growth reference data for infants and children
- used the prescriptive approach and hence, approximates a standard
- applicable to all children everywhere regardless of ethnicity, socio-economic status and type of living
WHO multicenter growth reference data for infants and children
Individual eligibility criteria for the WHO multicenter data (5)
- no known health or environmental constraints to growth
- no maternal smoking before or after delivery
- single term birth
- absence of significant morbidity
- mothers willing to follow MGRS feeding recommendations
MGRS feeding recommendations
- exclusive or predominant breastfeeding for atleast 4 months
- introduction of complimentary foods by the age of 6 months
- continued breastfeeding for atleast 12 months
What makes the MGRS data different?
- provides prescriptive data that describes how children should grow
- breastfeeding as the biological norm and establishes breastfed infant as the normative growth model
- international standard
- new innovative growth indicators
- longitudinal nature of the study allowed the development of growth velocity standards
- development of accompanying windows of achievement for 6 key motor development milestones
- provides unique link to physical growth and motor development
