Comparison of Population-Based and Convenience Cohorts
| Population Based | Convenience Sample | P Value* | |
|---|---|---|---|
| Demographic variables | |||
| Age (y) | |||
| Mean ± SE | 9.7 + 0.6 | 9.6 + 0.6 | ≥.2 |
| Range | 2.0–19.0 | 2.1–18.2 | |
| Gender (male:female) | |||
| n | 36:26 | 35:20 | ≥.2 |
| % | 58%:42% | 64%:36% | |
| Race (white:black:other) | |||
| n | 41:21:0 | 35:16:4 | ≥.2 |
| % | 66%:34%:0% | 64%:29%:7% | |
| Clinical variables | |||
| GMFC level (levels 3:4:5) | |||
| n | 16:17:29 | 2:10:43 | .0005 |
| % | 26%:27%:47% | 4%:18%:78% | |
| Anticonvulsants (never:past only:current) | |||
| n | 20:17:25 | 12:14:29 | ≥.2 |
| % | 32%:27%:40% | 22%:25%:53% | |
| Fracture (no:yes) | |||
| n | 55:7 | 44:11 | ≥.2 |
| % | 89%:11% | 80%:20% | |
| Lower limb or scoliosis surgery (no:yes) | |||
| n | 29:33 | 28:27 | ≥.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) | |||
| n | 33:8:5:16 | 15:9:6:25 | .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) | |||
| n | 29:33 | 25:30 | ≥.2 |
| % | 47%:53% | 45%:55% | |
| Serum transthyretin level (mean ± SE) | 22.6 + 0.9 | 21.3 + 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.