Baseline characteristics of the eligibility groups in the study cohort
| Characteristic | Program eligibility group; % of eligibility group* | |
|---|---|---|
| Ineligible (n = 131 781) | Eligible (n = 128 712) | |
| Sociodemographic† | ||
| Age, yr, mean ± SD | 13.17 ± 0.28 | 13.17 ± 0.28 |
| Birth quarter | ||
| Jan.–Mar. | 24.3 | 24.2 |
| Apr.–June | 26.1 | 26.1 |
| July–Sept. | 25.7 | 25.8 |
| Oct.–Dec. | 23.9 | 23.9 |
| Residency | ||
| Urban | 85.3 | 85.8 |
| Rural | 14.0 | 13.5 |
| Missing‡ | 0.7 | 0.6 |
| Income quintile | ||
| 1 (lowest) | 16.6 | 15.0 |
| 2 | 18.4 | 17.8 |
| 3 | 20.6 | 21.1 |
| 4 | 22.0 | 23.1 |
| 5 (highest) | 21.4 | 22.1 |
| Missing‡ | 1.0 | 0.9 |
| Vaccination history§ | ||
| Measles–mumps–rubella¶ | 97.9 | 98.2 |
| Diphtheria, tetanus and pertussis¶ | 98.0 | 98.3 |
| Hepatitis B¶ | 84.1 | 82.0 |
| All 3 vaccines | 83.0 | 81.1 |
| Health services use**†† | ||
| Hospital admission | ||
| 0 | 98.0 | 98.2 |
| ≥ 1 | 2.0 | 1.8 |
| LOS, d, mean ± SD | 7.4 ± 15.6 | 8.0 ± 18.2 |
| Same-day surgery | ||
| 0 | 97.7 | 97.8 |
| ≥ 1 | 2.4 | 2.2 |
| Emergency department visits | ||
| 0 | 70.7 | 71.1 |
| 1 | 18.1 | 17.8 |
| ≥ 2 | 11.2 | 11.1 |
| Outpatient visits | ||
| 0 or 1 | 22.6 | 22.8 |
| 2–5 | 27.4 | 26.9 |
| 6–12 | 25.1 | 24.5 |
| ≥ 13 | 25.0 | 25.8 |
| Medical history | ||
| Cancer** | 0.7 | 0.7 |
| Mental health diagnosis** | 9.5 | 9.7 |
| Sexual health indicators**‡‡ | 0.7 | 0.7 |
| Down syndrome | 0.5 | 0.5 |
| Congenital malformations | 12.4 | 11.8 |
| Intellectual disability§ | 0.7 | 0.7 |
Note: LOS = length of stay, SD = standard deviation.
↵* Except where indicated otherwise.
↵† At cohort entry.
↵‡ Because of missing or inaccurate postal code.
↵§ Between birth and cohort entry.
↵¶ At least 1 dose.
↵** In the 2 years before cohort entry.
↵†† Categories determined on the basis of the frequency distribution.
↵‡‡ Composite of sexually transmitted infections, cervical dysplasia, Papanicolaou smear and pregnancy.