TABLE 1.

Comparison of Population-Based and Convenience Cohorts

Population BasedConvenience SampleP Value*
Demographic variables
 Age (y)
  Mean ± SE9.7 + 0.69.6 + 0.6≥.2
  Range2.0–19.02.1–18.2
 Gender (male:female)
  n36:2635:20≥.2
  %58%:42%64%:36%
 Race (white:black:other)
  n41:21:035:16:4≥.2
  %66%:34%:0%64%:29%:7%
Clinical variables
 GMFC level (levels 3:4:5)
  n16:17:292:10:43.0005
  %26%:27%:47%4%:18%:78%
 Anticonvulsants (never:past only:current)
  n20:17:2512:14:29≥.2
  %32%:27%:40%22%:25%:53%
 Fracture (no:yes)
  n55:744:11≥.2
  %89%:11%80%:20%
 Lower limb or scoliosis surgery (no:yes)
  n29:3328:27≥.2
  %47%:53%51%:49%
 CHQ z score (mean ± SE)−0.9 + 0.2−0.8 + 0.2≥.2
Nutrition variables
 Feeding difficulty (no:mild:mod:severe)
  n33:8:5:1615:9:6:25.04
  %53%:13%:8%:26%27%:16%:11%:45%
 Triceps skinfold z score (mean ± SE)−0.4 + 0.1−0.9 + 0.2.04
 Tube feedings ever (no:yes)
  n29:3325:30≥.2
  %47%:53%45%:55%
 Serum transthyretin level (mean ± SE)22.6 + 0.921.3 + 0.8≥.2
Growth variables
 Height z score (mean ± SE)−2.5 + 0.2−3.3 + 0.3.01
 Weight z score (mean ± SE)−1.8 + 0.3−3.5 + 0.4.002
Bone density variables
 Distal femur z scores
  Region 1 (mean ± SE)−2.6 + 0.2−3.6 + 0.2.001
  Region 2 (mean ± SE)−2.8 + 0.2−3.8 + 0.2.003
  Region 3 (mean ± SE)−2.6 + 0.2−3.7 + 0.3.001
  Lumbar spine z score (mean ± SE)−1.8 + 0.1−2.3 + 0.1.006
  • * Statistical comparison between the population-based and convenience cohorts.