Criteria for Determining Disability in Infants and Children
Summary
Evidence Report/Technology Assessment: Number 73
Under its Evidence-based Practice Program, the Agency for Healthcare Research and Quality (AHRQ) is developing scientific information for other agencies and organizations on which to base clinical guidelines, performance measures, and other quality improvement tools. Contractor institutions review all relevant scientific literature on assigned clinical care topics and produce evidence reports and technology assessments, conduct research on methodologies and the effectiveness of their implementation, and participate in technical assistance activities.
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Overview / Causes of Short Stature in Children / Reporting the Evidence / Methodology / Findings / Future Research / Availability of Full Report
Overview
The Social Security Administration (SSA)
requested that the Agency for Healthcare
Research and Quality (AHRQ), through its
Evidence-based Practice Center (EPC) program,
provide a systematic review of the scientific
evidence about whether short stature in a child
due to a medically determinable cause may be
associated with disability, whether skeletal
dysplasias in a child may be considered a
disability, and whether decreasing growth
velocity in a child with a chronic disease may
serve as an indicator of severity of the disease.
The population of interest includes children age
17 years or younger, both male and female, of
all racial, ethnic, and socioeconomic groupings.
The evidence report was prepared to assist
SSA in updating its Listing of Impairments and
revising its disability policy, as may be
appropriate.
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Causes of Short Stature in Children
There are multiple causes of short stature.
The most common causes are familial short
stature (FSS) and constitutional growth delay
(CGD). FSS occurs when a child has height
below the third percentile due to a genetic
tendency to short stature in his or her family.
Children with FSS typically reach adult height
consistent with their family background. CGD
occurs when a child is shorter than would be
expected by her or his genetic background and
no determinable medical cause of the short
stature can be found. Often children with CGD
experience a delayed onset of pubertal
development and usually obtain normal or near
normal adult height. Neither FSS nor CGD is
considered to be due to medically determinable
causes in most cases. Since it can be difficult to
differentiate between these two conditions, the
term isolated short stature (ISS), is often used
interchangeably for both FSS and CGD.
Medically determinable causes of short stature
include abnormalities in the growth hormone
axis such as decreased growth hormone
production and diminished response to growth
hormone. Other endocrine abnormalities such
as hypothyroidism and Cushing disease may
lead to short stature and a variety of genetic
disorders including chromosomal, metabolic,
and single gene disorders can also result in short
stature.
Skeletal dysplasias are genetic disorders that
result in abnormal formation of part or all of the
skeleton. Not all skeletal dysplasia will result in
short stature. The skeletal dysplasias most likely
to lead to short stature are those that involve
formation and growth of the long bones and/or
the spine.
The presence of a chronic disease in a child
has long been known to be a risk factor for
decreased growth to a varying degree. However,
the underlying cause of the decreased growth
has not been determined in all chronic diseases.
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Reporting the Evidence
The following key questions were refined by
the EPC Evidence Review Team and technical
experts from those posed by the SSA.
Question 1. Is short stature (height <5th
percentile) as a result of a medically
determinable impairment associated with severe
functional limitations, according to, but not
limited to, SSA's definition of disability?
Question 2. What is the evidence that short
stature (height <5th percentile) due to a skeletal
dysplasia is disabling according to, but not limited to, SSA's
definition of disability? If so, are children disabled by virtue of
their size or other features of their conditions?
Question 3. What is the evidence that a sustained decrease
in linear growth velocity can be used as a marker of severity of
an underlying disease? Is such a process likely to be disabling?
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Methodology
Definition of Short Stature
A range of definitions of short stature among children
exists. In general, short stature has been defined as a height less
than the 3rd percentile. This corresponds to a value of 1.9
standard deviations below the mean height (which is
commonly rounded up to 2.0). However, many studies use a
variety of definitions including height less than the 5th and
10th percentiles (corresponding to 1.65 and 1.3 standard
deviations below the mean, respectively). The total number of
children who have short stature due to either a medically
determinable cause or a skeletal dysplasia as opposed to FSS
has not been reported. However, by definition, approximately
2.2 million American children have short stature (US Census,
2001).
Literature Search
Systematic searches were performed for full journal articles
of original data. The primary search for the literature review
consisted of a MEDLINE® search from 1966 through
February 2001, with updates through October 2001.
Supplemental searches were also performed in ERIC, PsycInfo,
Healthstar and EMBASE. Additional studies were identified
from reference lists of review and primary articles, and from
domain experts.
Development of the search strategies was an iterative
process that included input from domain experts. Keywords
from known relevant studies were used to refine and focus the
final search strategies used.
Study Selection
Including studies found from other sources, a total of
13,537 English language citations were reviewed. Screening of
the abstracts and titles identified 825 articles potentially useful
to address the three report questions. A set of minimum
inclusion criteria were used in this initial screening: primary
articles reporting original data on at least 10 children that
provided primary or secondary evaluation of growth failure
and had a primary or secondary outcome of a potential
functional limitation. Studies could be cross-sectional or
longitudinal, prospective or retrospective, comparative or not.
Summarizing the Literature
A total of 825 studies were retrieved for careful evaluation.
Detailed examination of these articles identified 31 studies
that met inclusion criteria for Question 1, 31 studies for
Question 2, and 53 studies for Question 3. Detailed data
extraction was performed on these 115 studies.
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Findings
Question 1. Is short stature (height <5th percentile) as a
result of a medically determinable impairment associated
with severe functional limitations, according to, but not
limited to, SSA's definition of disability?
We reviewed 31 papers that provided information on
functional abilities among children with short stature due to
medically determinable impairments. A number of these
papers provided analyses from the same samples of children.
One study reported on different outcomes in two separate
papers. Therefore, 24 papers from 23 studies are summarized
here. Few studies explicitly examined functional impairment,
per se. Data are reported on the association of short stature
with academic achievement, intelligence, visual-motor skills,
psychomotor development, and teacher-graded behavior.
Fifteen of the 23 studies were prospective cross-sectional
studies; seven were prospective longitudinal studies; and one
was a retrospective longitudinal study. Two were of good
quality, eleven were of fair quality, and nine were of poor
quality. One study was of fair quality in its analysis of
intelligence, but of poor quality in its analysis of academic
achievement.
Based on the reviewed articles, no severe functional
limitations were found in children with short stature due to
growth hormone deficiency, multi-hormone deficiency, Turner
syndrome, Russell-Silver syndrome, or isolated short stature.
These specific causes of short stature were chosen because they
allowed us to isolate the effect of short stature and thus enable
us to determine if there was an increased risk for disability
related problems just due to short stature. The articles focused
on intelligence, academic achievement, behavior, visual-motor
perception, and psychomotor development. In each of these
categories, children with short stature either had testing that
was not significantly different from the controls or from the
population mean, or if the testing were significantly poorer it
was still for the most part within one standard deviation (SD)
of the population mean.
Association of Short Stature with Academic Achievement.
Eleven studies evaluated academic achievement in
approximately 996 children with short stature as a result of a
medically determinable impairment. Five of the studies found
that children with short stature had academic achievement
scores at or above the population norm. The other six studies
found scores below the population norm but the great
majority was still within one SD of the mean. These results
imply that children with short stature do not have enough
difficulties with academic achievement to qualify as a
disability. A major limitation in five of the studies was the
exclusion of children with a low intelligence quotient (IQ).
Association of Short Stature with Intelligence. Twenty-one
studies evaluated IQ in approximately 1,156 children with
short stature as a result of a medically determinable
impairment. Fifteen studies found short stature children to
have IQs at or above the population mean, while the
remaining studies reported IQs for the most part less then one
SD below the mean. Three of the studies that found IQs at or
above the mean excluded children with low IQs. The studies
were limited by the IQ exclusion and also by an absence of a
control population in many of the studies. Future studies are
required to better delineate this question.
Association of Short Stature with Visual-motor Skills.
Only three studies involving 81 patients could be found that
evaluated visual-motor perception in children with short
stature. All three found significantly lower visual-motor skills
in the evaluated children. These studies, however, were limited
by their reporting of the data. Furthermore, it is not clear how
a decrease in visual-motor skill can be correlated with the SSA
definition of disability. Future studies are needed to evaluate
disabilities caused by functional limitations in visual-motor
skills.
Association of Short Stature with Psychomotor Development. One poor quality study evaluated 14 children
with short stature due to Russell-Silver syndrome for
psychomotor development by the Denver Developmental
Screening Test. These children were found to have delays in
meeting their developmental landmarks. However, the value of
this finding in relation to disability is questionable since the
children did eventually meet their developmental landmarks
(e.g., walking). Future studies are needed to determine the
significance of these findings.
Association of Short Stature with Behavior. Teacher-based
evaluation of behavior in children with short stature was
reported in five studies involving 274 children. In general,
behavior in the children with short stature was not
significantly different from the controls. Exceptions to this
were increased hyperactivity reported in one study, increased
locus of control in another study, and general increased
behavior problems in a third study. It is difficult to extrapolate
behavior in general from these studies since they tended to use
different tests, and the test results do not always overlap. In
addition, sub-group results were not given for each study.
Furthermore, the value of behavioral impairments for
determining a child's level of disability is questionable. Further
studies are needed that evaluate large groups of non-selected
short stature children, use the same behavior-based test,
compare results to matched controls, and determine likelihood
of disability.
Question 2. What is the evidence that short stature
(height <5th percentile) due to a skeletal dysplasia is
disabling according to, but not limited to, SSA's definition
of disability? If so, are children disabled by virtue of their
size or other features of their conditions?
There were 31 papers from 25 study groups that provided
information on functional abilities among children with short
stature due to skeletal dysplasia. Of the studies, 22 were
prospective cross-sectional studies; 5 were prospective
longitudinal studies; 2 were retrospective longitudinal; and 2
were retrospective cross-sectional. One was of good quality, 16
were of fair quality, and 12 were of poor quality. One study
was of good quality in its analysis of academic achievement,
but of fair quality in its analysis of ambulation and mobility.
One study was of fair quality in its analysis of neuromuscular
function and range of motion, but of poor quality in its
analysis of ambulation and mobility.
Based on the articles reviewed, children with skeletal
dysplasias were not at increased risk of having severe
impairments in intelligence, academic achievement, or
psychological outcome. There was an increased risk for delay
in achievement of motor skills in children with achondroplasia
and osteogenesis imperfecta, and decreased ambulation, range
of motion, and mobility in children with more severe forms of
osteogenesis imperfecta. The results for hearing impairment,
respiratory dysfunction, and spinal curvature appear to
indicate an increased risk for impairment in these three areas,
but the studies were limited in the number of children
evaluated and how the samples were selected, thus making it
difficult to arrive at a definitive conclusion in these areas.
Association with Academic Achievement. Three studies
examined academic achievement among 84 children with
achondroplasia or osteogenesis imperfecta. In two studies,
achondroplasia patients scored lower than control groups, yet
remained in the normal range. Further studies on this issue are
needed to evaluate a larger population of children with
achondroplasia, osteogenesis imperfecta, and other types of
skeletal dysplasias.
Association with Intelligence. Five studies with 116
children evaluated intelligence in children with
achondroplasia, osteogenesis imperfecta, and other skeletal
dysplasias. No evidence of significantly impaired intelligence
was found in any of the skeletal dysplasias by intelligence
testing with all scores either above the population norm or
within 0.5 SD of the norm. These studies were generally small
for the comparisons made. Further studies on this issue are
needed to evaluate a larger population with skeletal dysplasias
clearly defined by up-to-date standards.
Association with Psychomotor Development. Six studies
involving a total of 196 children found generally delayed
achievement of psychomotor abilities or development in
children with achondroplasia and osteogenesis imperfecta.
Each group evaluated was small, used different testing
instruments, and had varying ages of subjects. Furthermore,
none was followed longitudinally. Clinically useful conclusions
about ultimate motor function in children with skeletal
dysplasias cannot be made from these studies. Larger,
longitudinal studies are needed that test psychomotor
functional abilities.
Association with Neuromuscular Function. From review of
the available literature, children with short stature due to
various skeletal dysplasias appear to be at risk for
neuromuscular abnormalities. Six studies with 185 children
evaluated neuromuscular function in children with skeletal
dysplasias. The four studies that looked solely at children with
achondroplasia found varied abnormalities. The three that
measured strength found substantial weakness and hypotonia.
Asymmetry, sensory deficits, poor coordination, and seizures
were found in frequencies higher than controls or than are
expected in the healthy population. All studies highlighted the
significant risk of often occult cervical cord compression in
these young children. The one paper that evaluated
osteogenesis imperfecta found substantial muscle weakness in
children who are moderately to severely affected by their
disease. The one paper that reviewed other skeletal dysplasias
found cervical cord complications in children with Morquio
disease. Further studies of children with skeletal dysplasias,
especially achondroplasia, are needed to better delineate the
extent of neuromuscular impairment.
Association with Ambulation and Mobility. Of the eight
papers considering ambulation and mobility in children
(n=345) with short stature due to skeletal dysplasia, all
considered children with osteogenesis imperfecta. All found
significant impairment in ambulation, with greater
impairment, as expected, in patients with more severe disease.
Children with the less severe types of osteogenesis imperfecta
(tarda, Type I, Type IV) were more likely to attain some
walking capability, although a substantial proportion of these
children did require assistance. Orthopedic abnormalities such
as scoliosis, decreased range of motion, decreased muscle
strength, and fracture contribute to limitations of ambulation.
All of the studies were of small size; although given the rarity
of osteogenesis imperfecta, the studies were of reasonable size.
Definitions of levels of ambulation were consistent and fairly
objective. Studies of ambulation and mobility disabilities are
necessary for children with skeletal dysplasias other than
osteogenesis imperfecta.
Association with Limb Range of Motion. Two studies
evaluated upper and lower range of motion (ROM)
abnormalities in children with various types of osteogenesis
imperfecta (n=40) and with achondroplasia (n=41).
Decreased ROM was found in children with osteogenesis
imperfecta, but no such correlation was seen in children with
achondroplasia. Decreased lower extremity ROM may impact
on ability to independently ambulate. Decreased upper
extremity ROM may limit an individual's independence by
reducing his or her ability to engage in self-care. Further
studies are necessary to better delineate the connection
between limb ROM and various skeletal dysplasias.
Association with Spinal Curvature. Four papers assessed
spinal deformities in 209 children with short stature due to
skeletal dysplasia. Three studied children with osteogenesis
imperfecta, and one studied children with diastrophic
dysplasia. A high prevalence of scoliosis was found in children
with both conditions. One study also found a high prevalence
of pathologic kyphosis. All studies, however, likely represent a
selected, perhaps more severe, population of patients followed
by academic medical centers. Thus to find prevalence in the
general population of individuals with skeletal dysplasias, it
will be necessary to evaluate scoliosis and kyphosis in a group
of unselected individuals with skeletal dysplasias.
Association with Hearing Loss. Of the six studies that
reported on hearing loss in 151 children with skeletal
dysplasia, only three performed objective hearing testing. All
papers that reported actual hearing testing in young
osteogenesis imperfecta patients reported a sizable proportion
with hearing loss, although the prevalence varied due to
selection and cohort size differences. Subjective reports of
hearing problems in achondroplasia patients were common.
However, one study found no difference in self-reported
hearing function between children with a mix of skeletal
dysplasias, including achondroplasia, and control children. The
available literature supports that children with at least some
skeletal dysplasias, specifically achondroplasia and osteogenesis
imperfecta, are at risk for hearing problems. Further studies
with a larger, unselected population of children with skeletal
dysplasia are needed to better define the extent, severity, and
type of hearing loss.
Association of Short Stature with Respiratory Dysfunction.
Of the four papers evaluating sleep and
respiratory dysfunction in 94 children with achondroplasia, all
found a high incidence of abnormality, including central
hypopnea, central apnea, and obstructive apnea. All four
papers, however, reported on small numbers of children. Two
of the groups contained patients referred for their respiratory
or neurologic symptoms, and therefore may not represent the
general achondroplasia population. Further studies that look at
larger groups of non-selected achondroplasia patients are
needed to define the prevalence of apnea in this population.
Little information on pulmonary function in children with
skeletal dysplasia was found. One group found abnormal
pulmonary function in a small group of children with
achondroplasia, and one found no significant abnormality in a
smaller group of children with osteogenesis imperfecta. More
data are required before meaningful conclusions can be drawn.
Association of Short Stature with Psychological
Outcomes. Only one paper adequately studied the association
of short stature due to skeletal dysplasia with psychological
outcomes. The study found no evidence for increased rates of
depression or anxiety in children with skeletal dysplasia.
Further studies that evaluate psychological problems such as
depression and anxiety are needed to validate these results.
Question 3. What is the evidence that a sustained decrease
in linear growth velocity can be used as a marker of
severity of an underlying disease? Is such a process likely to
be disabling?
We reviewed 53 articles that evaluated whether a sustained
decrease in linear growth velocity can be used as a marker of
the severity of 12 medical conditions and whether such a
process is likely to be disabling. One study separately evaluated
children with both asthma and congenital heart disease. The
evidence from four conditions—congenital heart disease,
Crohn's disease, juvenile rheumatoid arthritis, and human
immunodeficiency virus (HIV) infection—appears to indicate
that a sustained decrease in linear growth velocity can be used
as a marker of the severity of these underlying conditions.
Evidence is less clear for asthma, diabetes, beta-thalassemia,
chronic kidney failure, and atopic dermatitis. There was only
one study each for cerebral palsy, sickle cell anemia, and
congenital adrenal hyperplasia, so it is difficult to draw
conclusions for these conditions. None of the studies
addressed the question of whether the process of having a
decreasing linear growth velocity was likely to be disabling.
Association of Severity of Asthma. Eleven studies evaluated
the association between severity of asthma and height or
height velocity in 3,778 children. Overall, the studies did not
find a consistent result. Six of the studies found no association
between severity of asthma and growth retardation. No study
found an association between mild asthma and growth
retardation.
Studies were limited by poorly defined samples, limited data
and analysis, missing data and, frequently, by the fact that
severity of disease was measured by steroid treatment. These
studies do not clearly provide evidence that a sustained
decrease in linear growth velocity can be used as a marker of
severity of asthma or whether a decrease in growth velocity is
likely to be disabling. Future well-designed studies are needed.
Congenital Heart Disease. Six studies evaluated the
association between severity of congenital heart diseases and
height or height velocity in 1,784 children. Many studies were
limited by incomplete data and statistical analysis and some
studies were limited because they excluded children with the
most severe congenital cardiac defects. Given the limitations,
the results do suggest that height and height velocity
retardation is seen in children with severe congenital heart
defects and may be a marker for more severe disease. Whether
the decrease in height or height velocity in itself is disabling is
not answered.
Insulin-dependent Diabetes Mellitus. Eleven studies
involving 1,099 children evaluated the relationship between
growth retardation and control or severity of insulin-dependent
diabetes mellitus. Overall, the studies showed
mixed results with five studies demonstrating a positive
relationship between poor diabetes control or increased
severity of disease and decreased growth velocity. Several
studies associated growth deceleration with peripubertal onset
of illness. Some studies were limited because they did not use a
well-defined, objective measure, such as glycohemoglobin
(Hgb A1c), to assess severity or control. Some studies were
limited by unclear statistical analysis, lack of specific data
included, or summary results. These studies did not find clear
evidence that a sustained decrease in linear growth velocity can
be used as a marker of severity of diabetes or whether a
decrease in linear growth velocity is in itself disabling. Further
prospective, longitudinal studies of the linear growth of
children with diabetes mellitus, using objective measures of
control like Hgb A1c, are needed to clarify whether a decrease
in linear growth velocity may be a marker for severity of
disease.
Beta-Thalassemia. There were three studies involving 295
children that evaluated the relationship between growth
retardation and severity of anemia in beta-thalassemia. One study
showed a relationship between increased severity of anemia
and reduced height, and one study showed a trend toward
increased severity of disease and decreased growth. The studies
were limited by incomplete data reporting and by inconsistent
definitions of severity. These studies do not show clear
evidence that a sustained decrease in linear growth velocity can
be used as a marker of the severity of the disease. Prospective
longitudinal cohort studies with clear definitions of severity
(i.e., hemoglobin levels) and measurements of height velocity
may answer the question.
Inflammatory Bowel Disease. There were three studies
involving 660 children that evaluated the relationship between
growth retardation and the severity of inflammatory bowel
disease. Two studies included only children with Crohn's
disease. The other two studies included children with both
Crohn's disease and ulcerative colitis. Disease severity was
associated with height velocity among children with both
Crohn's disease and ulcerative colitis; however, height was not
significantly associated with disease severity in any study.
There are no data presented to suggest that the process of
growth failure is likely to be disabling. Further prospective
longitudinal studies that include larger numbers of patients
who have ulcerative colitis and Crohn's disease, and that
compare both with population standards and with each other,
may clarify whether growth retardation is a marker associated
with severity of all inflammatory bowel diseases, or is related
to one in particular.
Juvenile Rheumatoid Arthritis. Three studies involving 153
children evaluated the relationship between growth retardation
and the subtypes or severity of juvenile rheumatoid arthritis.
All studies indicated an association between decreased growth
velocity and increased severity of the disease. One study noted
that height velocity normalized after the first year of treatment.
The studies were limited in two cases by excluding children
with the most severe disease, by incomplete statistical analyses
in one, and by poorly defined outcomes in another. With
these caveats, the studies suggest that a decrease in linear
growth velocity is associated with more severe disease and may
serve as a marker of severity of the underlying disease. There
are no data reported addressing the question of whether
decreased growth velocity is in itself disabling. Future well-designed
studies with broad inclusion criteria are needed to
clarify the issue.
Chronic Kidney Disease. Ten studies involving 684
children evaluated the relationship between growth retardation
and severity of chronic kidney disease. Eight of the studies
found a positive relationship between increased severity of
kidney failure and decreased height or height velocity. Single
studies of sub-populations of children with autosomal recessive
polycystic kidney disease (ARPKD) and very young children
with chronic kidney disease found no association of disease
severity with height velocity. There was conflicting evidence
about the role of steroid use in causing growth retardation.
Some studies were limited by using a severity marker other
than glomerular filtration rate, by small sample sizes, or by
incomplete data reporting. Overall, the studies suggest that a
decrease in linear growth velocity is associated with the severity
of the underlying disease but this finding was not universal.
No data were available to assess if a decreased height velocity is
in itself disabling. Additional prospective, longitudinal studies
that evaluate whether a decrease in linear growth velocity can
be used as a marker of severity of underlying kidney disease are
needed.
Human Immunodeficiency Virus Infection. There were
two studies evaluating the relationship between growth
retardation and progression to disease in 60 HIV-positive
children. Both studies found that linear growth retardation is a
marker for progression to active disease in HIV-positive
children and linear growth deceleration may precede the onset
of symptoms of active disease. These studies were limited by
incomplete data reporting and poorly defined methods,
predictors, and outcomes. Despite the limitations, the studies
do indicate that a sustained decrease in linear growth velocity
is a marker for progression from seropositive status to active
disease. No data were included that assess whether a decreased
linear growth velocity is in itself likely to be disabling. Larger,
prospective, longitudinal studies of the relationship between
decreasing linear growth velocity and progression of disease
could confirm the usefulness of decreased linear growth
velocity as a marker for increasing severity of disease.
Atopic Dermatitis. Two studies involving 148 children
evaluated the relationship between growth retardation and
severity of atopic dermatitis. The studies reported conflicting
results with one study reporting a positive association between
increased severity and decreased height and the other study
showing no association between increased severity and
decreased height or height velocity. In the first study the more
severely affected group had higher steroid use and some used
systemic steroids. In the second study, those using systemic
glucocorticoids were excluded from analysis. This study was
also limited by a failure to report complete results and a failure
to report statistical analyses. These studies do not clearly
provide evidence that a sustained decrease in linear growth
velocity is a marker for the severity of the underlying disease.
No data were provided that look at whether the process of a
decreasing linear growth velocity is in itself disabling. Further
prospective longitudinal studies are needed to clarify whether
growth velocity is affected by the severity of atopic dermatitis,
or whether the apparent effect is related to steroid treatment.
Cerebral Palsy. There was only one study with 81 subjects
that looked at the relationship between growth retardation and
cerebral palsy. The study did not find a significant association
between the type of cerebral palsy and decreased growth
velocity but cognitive impairment, and non-ambulatory status
were associated with decreased growth velocity. This suggests
that those more severely affected by both motor and non-motor
neurological deficits have decreased growth velocity.
This study was limited by the exclusion criteria, which likely
excluded the most severely affected children. No data were
presented to answer the question about whether the process of
having a decreasing linear growth velocity is in itself disabling.
Further prospective longitudinal studies of children with
varying severity of cerebral palsy are needed to confirm
whether a decreasing linear growth velocity is a marker for the
severity of the underlying disorder.
Sickle Cell Disease. There was only one study with 24
subjects that evaluated the association of growth retardation
with the severity of sickle cell disease. That study found a
positive association between severe sickle cell disease (measured
by need for transfusions and the number of crises) and
decreased height percentile compared to controls. The study
was small and did not explicitly compare less severe sickle cell
disease to more severe disease. The study also did not look at
height velocity as a predictor of more severe disease. Further
prospective longitudinal studies that compare larger numbers
of patients with mild, moderate, and severe sickle cell disease
are needed to determine if a decreasing linear growth velocity
can serve as a marker for the severity of the underlying disease.
Congenital Adrenal Hyperplasia. There was only one study
with 9 subjects that looked at the relationship between growth
retardation and congenital adrenal hyperplasia. It did not find
an association between number of escapes (more severe
disease) and decreased growth velocity. The study was limited
by its small size and by its reporting of results in graphic form
only. There is not clear evidence that a decreasing linear
growth velocity can be used as a marker for the underlying
severity of congenital adrenal hyperplasia. No data were
presented that look at whether the process of a decreasing
linear growth velocity is in itself disabling. Further prospective
longitudinal studies of larger numbers of patients with
congenital adrenal hyperplasia are needed to answer the
question of whether decreasing linear growth velocity can be
used as a marker for severity of the underlying disease.
Limitations
There were several limitations encountered in evaluating
Questions 1 and 2. Very few studies looked specifically at
disability as defined by SSA. Most studies in fact were looking
at functional ability such as IQ or academic achievement. Such areas are focused on in the published literature because they
allow for acquisition of data that can be compared to
published norms. Results from such studies have to be
extrapolated to determine if the children evaluated meet the
SSA definition of disability. For example, one SSA criterion of
disability includes acquiring and using information. Reduced
IQ in a child may lead to limitations in acquiring or using
information, but there is not a linear relationship between
decreased IQ and reduced ability to acquire and use
information. Even those studies that evaluated functional
impairment, such as those that evaluated inability or limitation
of walking, do not necessarily correlate directly with SSA's
definitions of disability.
One limitation to evaluating Question 3 relates to
difficulties in trying to correlate the severity of disease with
decreasing growth velocity. Frequently a report that details
height in a specific disorder does not directly correlate this
with severity of disease. Also the way in which severity of
disease was reported may vary between reports discussing the
same disease. The same problem was seen with reporting of
growth data, which is given in a variety of different formats
(e.g., one-time height, growth velocity, and standard deviation
from the mean). This makes it more difficult to determine the
overall validity of the results.
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Future Research
Further research is needed to better define the relationships
both between short stature and disability and between growth
velocity and severity of chronic disease. Research on disability
should focus on functional deficits rather than functional
ability. Studies that examine physical limitations directly
related to short stature are needed. Further prospective
longitudinal studies of growth velocity in chronic disease are
needed. Studies are needed of children of various ages,
including puberty. Studies need to clearly define severity of
disease and avoid confounding severity with treatment options.
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Availability of Full Report
The full evidence report from which this summary was
taken was prepared for AHRQ by the Tufts-New England Medical Center Evidence-based Practice Center under
contract number 290-97-0019. Printed copies may be obtained free of charge
from the AHRQ Publications Clearinghouse by calling 1-800-358-9295. Requesters should ask for Evidence Report/Technology Assessment No. 73, Criteria for
Determining Disability in Infants and Children: Short Stature.
The Evidence Report is also online on the National Library of Medicine Bookshelf, or can be downloaded as a PDF File (4.5 MB) [PDF Help].
Return to Contents
Current as of March 2003
AHRQ Publication No. 03-E025
Internet Citation:
Criteria for Determining Disability in Infants and Children: Short Stature. Summary, Evidence Report/Technology Assessment: Number 73. AHRQ Publication No. 03-E025, March 2003. Agency for Healthcare Research and Quality, Rockville, MD. http://www.ahrq.gov/clinic/epcsums/shortsum.htm
540 Gaither Road Rockville, MD 20850