TABLE 1.
Baseline Characteristics for the Subjects Randomly Assigned to the Control Group or Intervention (Prevaccination Oral Water Hydration) Group
| Control (n = 906) | Intervention (n = 901) | P | |
|---|---|---|---|
| Age, y | 15 (12–17)a | 15 (12–17)a | .62 |
| Sex (% female) | 49.6 | 53.0 | .15 |
| Race, % | .80 | ||
| White | 44.7 | 44.4 | — |
| African American | 43.9 | 42.4 | — |
| Asian American | 2.8 | 2.9 | — |
| American Indian | 0.1 | 0.2 | — |
| Native Hawaiian/Pacific Islander | 0.3 | 0.1 | — |
| Other | 5.2 | 6.4 | — |
| Missing | 3.0 | 3.6 | — |
| Ethnicity, % | .31 | ||
| Hispanic | 9.4 | 11.5 | — |
| Non-Hispanic | 89.4 | 87.1 | — |
| Missing | 1.2 | 1.3 | — |
| BMI, % | .58 | ||
| Normal | 60.0 | 60.1 | — |
| Overweight | 21.9 | 20.3 | — |
| Obese | 18.1 | 19.6 | — |
| Insurance status, % | .79 | ||
| Only public | 38.4 | 38.5 | — |
| Any private | 60.5 | 60.4 | — |
| None | 1.1 | 1.0 | — |
| Ever nearly passed out or passed out in the past 5 y, % |
— | ||
| In the heat | 14.5 | 15.5 | .55 |
| After a shot | 2.1 | 2.1 | .99 |
| After blood draw | 4.8 | 4.8 | .97 |
| After or during exercise | 19.2 | 17.1 | .24 |
| Tiredness at the time of enrollment, % | .43 | ||
| Not at all or a little bit | 93.8 | 94.7 | — |
| Very | 6.2 | 5.3 | — |
| Hunger at the time of enrollment, % | .18 | ||
| Not at all or a little bit | 87.3 | 85.1 | — |
| Very | 12.7 | 14.9 | — |
| Thirst at the time of enrollment, % | .12 | ||
| Not at all or a little bit | 88.0 | 90.3 | — |
| Very | 12.0 | 9.7 | — |
| Hours of sleep the previous night | 8 (7–9)a | 8 (7–9)a | .94 |
| Hours since last food | 3 (2–5)a | 3 (2–5)a | .57 |
| Hours since last drink | 2 (1–4)a | 3 (1–5)a | .09 |
| Prevaccination anxiety, % | .32 | ||
| None or slight | 79.3 | 77.0 | — |
| Mild | 12.1 | 12.5 | — |
| Moderate | 7.7 | 10.0 | — |
| Severe | 0.9 | 0.5 | — |
—
not applicable.
a
Median (IQR).