Table 1 Study population characteristics
Variable | Total | Male | Female | P Value |
|---|---|---|---|---|
Infants (N = 115,918) | ||||
Birth cohort | 115,918 | 59,779 (51.6%) | 56,139 (48.4%) | -- |
Mean age (months) | 2.2 (±1.28) | 2.21 (±1.24) | 2.23 (±1.33) | <0.001 |
Initial USa | 67,491 (58.2%) | 33,472 (56.0%) | 34,019 (60.6%) | <0.001 |
Positive US | 625 (0.93%) | 81 (0.24%) | 544 (1.60%) | <0.001 |
Physicians (N = 487) | ||||
General Practitioners (N = 50) | Pediatricians (N = 437) | |||
Practice volume | 5110 (4.4%) | 110,289 (95.6%) | -- | |
Mean practice volume | 100 (±58.5) | 252 (±185.5) | -- | |
Initial referral | 1790 | 65,701 | -- | |
Referrals as a proportion of practice volume | 35.0% | 59.6% | <0.001 | |
Positive US | 19 (1.06%) | 606 (0.92%) | 0.631 | |