TABLE 2.

Bone Density z Scores: Univariate Analyses

NMean BMD z Score ± SE
Distal Femur Region 2Lumbar Spine
Demographic variables
 Age
  2.0–5.9 y31−2.9 ± 0.4−2.5 ± 0.2
  6.0–11.9 y50−3.0 ± 0.2−1.8 ± 0.1
  12.0–19.0 y36−3.7 ± 0.3−2.0 ± 0.2
P = .01P ≥ .2
 Gender
  Boys71−3.1 ± 0.2−2.1 ± 0.1
  Girls46−3.6 ± 0.3−1.9 ± 0.2
P = .1P ≥ .2
 Race
  White/other80−3.5 ± 0.2−2.0 ± 0.1
  Black37−2.7 ± 0.2−2.1 ± 0.2
P = .01P ≥ 0.2
Clinical variables
 GMFC level
  Level 318−1.8 ± 0.3−1.5 ± 0.2
  Level 427−3.1 ± 0.3−1.9 ± 0.2
  Level 572−3.8 ± 0.2−2.2 ± 0.1
P < .0001P = .03
 Anticonvulsants
  Never32−2.5 ± 0.3−2.1 ± 0.2
  Past only31−3.0 ± 0.3−1.8 ± 0.1
  Current54−3.8 ± 0.2−2.2 ± 0.2
P < .003P ≥ .2
 Fracture
  No99−3.1 ± 0.2−2.0 ± 0.1
  Yes18−3.9 ± 0.4−2.2 ± 0.4
P = .06P ≥ .2
 Temporary immobilization
  Never58−3.1 ± 0.3−2.2 ± 0.1
  Brief17−3.8 ± 0.4−1.7 ± 0.4
  Prolonged42−3.2 ± 0.2−2.0 ± 0.2
P ≥ .2P ≥ .2
 Children’s Health Status Questionnaire z score
  >−1.054−2.9 ± 0.2−1.9 ± 0.1
  −1.0 to −2.024−3.1 ± 0.4−2.4 ± 0.2
  <−2.031−3.7 ± 0.3−2.1 ± 0.3
P ≥ .2P = .09
Nutrition variables
 Triceps skinfold z score
  >031−3.0 ± 0.3−1.6 ± 0.2
  0 to −1.032−3.4 ± 0.3−2.1 ± 0.2
  −1.0 to −2.046−3.3 ± 0.3−2.3 ± 0.2
  <−2.08−3.5 ± 0.5−1.9 ± 0.3
P ≥ .2P = .003
 Feeding problems
  None48−2.6 ± 0.3−1.7 ± 0.1
  Mild17−2.9 ± 0.3−2.2 ± 0.3
  Moderate11−4.4 ± 0.8−2.3 ± 0.3
  Severe41−3.9 ± 0.2−2.3 ± 0.2
P = .0003P = .02
 Currently tube fed
  No84−2.9 ± 0.2−2.0 ± 0.1
  Yes33−4.0 ± 0.3−2.3 ± 0.2
P = .001P ≥ .2
 Calcium intake
  Adequate (>1000)64−3.2 ± 0.2−1.9 ± 0.1
  Marginal (500–1000)46−3.3 ± 0.3−2.1 ± 0.2
  Low (<500 mg/d)7−3.4 ± 0.5−2.7 ± 0.4
P ≥ .2P ≥ .2
 Serum transthyretin
  Normal (>18 mg/dL)51−3.4 ± 0.3−2.0 ± 0.1
  Marginal (16–18 mg/dL)7−3.6 ± 0.6−2.9 ± 0.3
  Low (<16 mg/dL)5−3.4 ± 0.5−2.9 ± 0.7
P ≥ .2P = .02
Growth variables
 Height z score (based on sitting knee height)
  >−1.015−2.5 ± 0.3−1.9 ± 0.4
  −1.0 to −2.025−2.8 ± 0.4−1.8 ± 0.2
  <−2.077−3.6 ± 0.2−2.2 ± 0.1
P = .0003P ≥ .2
 Weight z score
  >−1.031−2.5 ± 0.3−1.4 ± 0.2
  −1.0 to −2.027−3.0 ± 0.2−2.2 ± 0.2
  <−2.059−3.9 ± 0.2−2.3 ± 0.1
P < .0001P = .0001
 Arm circumference z score
  >036−2.6 ± 0.3−1.3 ± 0.1
  0 to −1.022−3.0 ± 0.4−2.2 ± 0.3
  −1.0 to −2.028−3.2 ± 0.3−2.2 ± 0.2
  <−2.031−4.4 ± 0.3−2.6 ± 0.1
P < .0001P < .0001
Other serum variables
 25 OHD
  Adequate (>20 ng/mL)36−3.5 ± 0.3−2.2 ± 0.2
  Marginal (15–20 ng/mL)27−3.4 ± 0.3−2.2 ± 0.2
  Low (<15 ng/mL)13−3.2 ± 0.4−2.2 ± 0.3
P ≥ .2P ≥ .2
 N-telopeptides (bone resorption marker)
  Low tertile (<41 nm/L)24−3.5 ± 0.4−1.8 ± 0.2
  Mid tertile (41–57 nm/L)23−3.3 ± 0.4−2.2 ± 0.2
  High tertile (>57 nm/L)24−3.1 ± 0.3−2.2 ± 0.3
P ≥ .2P ≥ .2
 Osteocalcin (bone formation marker)
  Low tertile (<38 ng/mL)25−3.9 ± 0.5−2.4 ± 0.2
  Mid tertile (38–59 ng/mL)25−3.3 ± 0.3−2.2 ± 0.2
  High tertile (>59 ng/mL)26−3.3 ± 0.3−1.9 ± 0.3
P ≥ .2P ≥ .2
 Abnormal phosphorous, calcium, or alkaline phosphatase
  No62−3.3 ± 0.2−2.2 ± 0.1
  Yes13−4.0 ± 0.6−2.2 ± 0.3
P ≥ .2P ≥ .2