Bone Mineral Accretion in Young Children
Condition: Bone Mineral Density Reference Data
Study type: Observational

Summary: 
      Compromised bone strength and increased fracture susceptibility pose significant morbidity
      and health care costs in children. Inadequate childhood bone accretion also may have lifelong
      consequences. Bone fragility among children with chronic medical conditions is a special
      concern. Identifying children at-risk for bone fragility and factors affecting bone strength
      requires understanding normal bone development. Dual energy x-ray absorptiometry (DXA) is the
      most common method for measuring bone mineral content and bone density in children. There are
      bone density reference data for children ages 5-20 years. An important gap is the lack of
      reference data for children ages < 5 years, who also experience numerous medical conditions
      that threaten their bone health.

      Growth and body composition influence bone mineral accrual, and are important for
      interpreting bone density measurements in children with conditions that threaten bone health.
      Gross motor skills and subsequent physical activity may also affect bone accrual. Children
      with chronic illness are at risk of altered body composition, delayed growth and gross motor
      skills, and restricted physical activity. Understanding independent effects of growth, body
      composition, gross motor skills and physical activity on bone accrual will improve
      interpretation of bone density measurements and has important research and clinical
      applications for identifying risk factors and therapies for young children.

      This study will involve a longitudinal cohort of 280 children studied every 6 months for 3
      years, and a cross-sectional cohort of 240 children measured once. The study will be
      conducted at 2 clinical centers [Cincinnati Children's Hospital Medical Center (CCHMC) and
      the Children's Hospital of Philadelphia (CHOP)] with equal enrollment at both centers.
      Measurements will include bone density, growth and body composition, dietary intake, sleep,
      physical activity and gross motor skills. Results from this study will enable clinical bone
      health assessment of young children with disorders that threaten bone health, and identify
      factors that affect bone accrual.
    

Detailed description: 
      This study seeks to understand bone mineral accrual in children 1 to 5 years of age. Many
      young children have chronic medical conditions that threaten bone health and increase their
      susceptibility to fractures. Over the last 10 years our team at Cincinnati Children's
      Hospital Medical Center (CCHMC) has helped develop reference data that have enabled
      clinicians to identify children 5 to 20 y with low bone density for age and optimize their
      medical care. A glaring deficit is the inability to evaluate bone health of young children <
      5 y due to lack of appropriate bone density reference data. This gap is problematic as there
      are numerous clinical conditions (e.g., neuromuscular disease, cancer, glucocorticoid
      treatment, extreme prematurity) that threaten bone health in this young age group.

      The primary goal of our new study is to develop bone mass and density reference data to aid
      identification of children 1 to 5 years of age with bone deficits. A first step is to
      characterize the age-related changes in bone accrual at multiple skeletal sites and determine
      when sex and race differences in bone mass and density emerge.

      The second goal of this study is to assess the influence of growth, body composition, gross
      motor skills and physical activity on bone mineral accrual in young children. In older
      children, the need to account for growth and lean mass when interpreting bone measurements
      has been demonstrated. The best way to do this in young children is unknown. Pronounced
      changes in gross motor skills, locomotion and physical activity also occur during early
      childhood. It is well appreciated that mechanical loads on the growing skeleton promote bone
      mineral accrual. but how gross motor skills and physical activity impact bone development in
      children 1 to 5 years of age is unknown. Understanding the impact of growth, body
      composition, motor skill development, and physical activity on bone accrual in young children
      is important for interpretation of clinical bone density measurements. These characteristics
      are often affected in young children with chronic medical conditions.

      This study will enroll 520 healthy children between 1 to 5 years of age; half will be
      recruited at CCHMC and half at Children's Hospital of Philadelphia.

      This study is unique since no previous studies have addressed these issues in children 1-5 y.
      It is clinically relevant as findings will facilitate medical care of children with chronic
      medical conditions that threaten bone health, and it will develop and validate novel methods
      for bone and body composition assessment in this age range. It will also add generalizable
      knowledge to enhance understanding of the growing skeleton, and its relationship to motor and
      somatic development. Since poor bone mineral accrual can have lifelong consequences, this
      study addresses the major public health concern of osteoporosis.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Community sample