Constructing an Insulin-Like Growth Factor-based Prediction Model



Status:Recruiting
Conditions:Endocrine
Therapuetic Areas:Endocrinology
Healthy:No
Age Range:3 - 14
Updated:2/7/2015
Start Date:August 2004
Contact:Patricia Park, MD
Email:ppark@mednet.ucla.edu
Phone:(310)825-6244

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Serum insulin-like growth factor-I (IGF-I) measurements have been shown to correlate well
with growth hormone action and effect, and recent data show that serum IGF-I may be related
to safety and efficacy of growth hormone (GH) treatment in patients. Some studies indicate
that high IGF-I levels are associated with increased cancer risk, and low IGF-I levels are
associated with increased risk for cardiovascular disease. Studies in children also show
that the serum IGF-I level is correlated with the change in height score achieved (that is,
the higher the IGF-I level, the greater the gain in height). Pediatric endocrinologists
have therefore begun to use serum IGF-I levels, in addition to growth rate and weight gain,
to adjust the GH dose in treated children.

Although monitoring of serum IGF-I levels is becoming standard of care in patients begin
treated with GH, there are few guidelines regarding the actual logistics of adjusting GH
dose. As serum IGF-I level has been linked to both safety and efficacy of GH treatment, the
ideal practice would be to maintain serum IGF-I levels within a certain target range. The
overall goal of our study is to construct a mathematical model which predicts the change in
GH dose necessary to achieve a desired change in IGF-I level.

Hypotheses to be tested by our study include the following: IGF-I measurement has a role in
optimization of GH therapy; GH dose change to achieve IGF-I changes are predictable; and
gender and puberty affect the relationship between dose change and target IGF-I changes.

The first phase of our study, previously approved by the UCLA IRB in August 2004, involved a
retrospective chart review and collection of preexisting data. We analyzed charts of
patients who underwent non-weight-based GH dose adjustments preceded and followed by a serum
IGF-I level. Data collected included patient's age, gender, height, weight, linear height
velocity, pubertal status, GH dose, IGF-I levels, disease condition (i.e., growth hormone
deficiency, idiopathic short stature, small-for-gestational age) and recording of any
adverse effects. Based on this data collected, we performed statistical analysis of the
relationship between GH dose change and change in IGF-I level achieved, and have found that
in prepubertal children, there is a significant relationship between the GH dose change and
change in corresponding IGF-I level. We have subsequently constructed a mathematical
prediction model that allows us to determine the GH dose change necessary to achieve a
desired IGF-I level, and in this second phase of our study, we plan to apply this
mathematical prediction model prospectively for guiding GH dose adjustments in prepubertal
children being treated with GH therapy.

Children being treated with GH are typically followed in the outpatient Endocrinology clinic
every 3-4 months, and our practitioners have routinely been obtaining serum IGF-I levels
(via venipuncture in the outpatient laboratory) for monitoring purposes. Validation of our
GH dose change/IGF-I change prediction model will require assessment of sequential serum
IGF-I level measurements immediately preceding a GH dose change, and again within 1-4 months
following the GH dose change. We plan to continue our retrospective and ongoing analysis of
patients who have paired values of GH dose adjustments preceded and followed by a serum
IGF-I level, in order that we may continue to fine-tune our prediction model for optimizing
GH dose adjustments.

Inclusion Criteria:

- Prepubertal patients,

- Male/female,

- Ages 3-14 yrs,

- Being treated with growth hormone for the conditions of growth hormone deficiency,
idiopathic short stature, and small-for-gestational age with failure to catch up to
the normal growth curve by age 2 years.

Exclusion Criteria:

- Patients being treated with growth hormone for other conditions such as Turner
syndrome, chronic renal failure, or Prader-Willi syndrome
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