Table 1.
Baseline Characteristics of the RBEL II Cohort*
| All Participants (n = 145) |
Baseline Covariates Based on 25-OH-VitD Level Cutoff of 20 ng/mL. Participants With Baseline 25-OH-VitD Levels |
Baseline Covariates Based on 25-OH-VitD Level Cutoff of 30 ng/mL. Participants With Baseline 25-OH-VitD Levels |
|||||
|---|---|---|---|---|---|---|---|
| < 20 ng/mL (n = 14) |
≥ 20 ng/mL (n = 131) |
P Value | < 30 ng/mL (n = 37) |
≥ 30 ng/mL (n = 108) |
P Value | ||
| Age at enrollment (months)a | 4.3 (2.9) | 2.8 (2.5) | 4.5 (2.9) | .04 | 3.5 (3.0) | 4.6 (2.9) | .06 |
| Gender (male) | 60.7% | 50.0% | 61.8% | .39 | 59.5% | 61.1% | .86 |
| Race | |||||||
| African American | 42.1% | 42.9% | 42.0% | .85 | 32.4% | 45.4% | .17 |
| White | 46.2% | 50.0% | 45.8% | 59.5% | 41.7% | ||
| Other/multiple | 11.7% | 7.1% | 12.2% | 8.1% | 13.0% | ||
| Birth weight (kg)† | 3.3 (0.5) | 3.2 (0.3) | 3.3 (0.5) | .43 | 3.4 (0.5) | 3.2 (0.5) | .10 |
| Birth length (cm) † | 50.4 (2.9) | 50.2 (2.3) | 50.4 (2.9) | .87 | 51.3 (2.8) | 50.0 (2.8) | .02 |
| Length of pregnancy (wks)† | 38.6 (1.4) | 38.3 (1.3) | 38.7 (1.4) | .39 | 38.5 (1.4) | 38.7 (1.4) | .63 |
| Season at Birth | |||||||
| Winter (December–February) | 29 (20.0%) | 2 (14.3%) | 27 (20.6%) | .5 | 5 (13.5%) | 24 (22.2%) | .43 |
| Spring (March–May) | 31 (21.4%) | 5 (35.7%) | 26 (19.9%) | 11 (29.7%) | 20 (18.5%) | ||
| Summer (June–August) | 38 (26.2%) | 4 (28.6%) | 34 (26.0%) | 9 (24.3%) | 29 (26.9%) | ||
| Fall (September–November) | 47 (32.4%) | 3 (21.4%) | 44 (33.6%) | 12 (32.4%) | 35 (32.4%) | ||
| Current eczema | 13.3% | 21.4% | 12.4% | .34 | 19.4% | 11.2% | .21 |
| Paternal asthma | 23.4% | 25.0% | 23.3% | .89 | 24.2% | 23.2% | .90 |
| Maternal asthma | 28.8% | 8.3% | 30.7% | .10 | 17.6% | 32.4% | .10 |
| Maternal smoking during pregnancy | 22.8% | 7.1% | 24.4% | .14 | 16.2% | 25.0% | .27 |
| Total IgE level (IU/mL)† | 24.1 (95.2) | 11.2 (32.6) | 25.4 (99.6) | .10‡ | 25.9 (98.0) | 23.4 (94.7) | .32‡ |
| Blood eosinophils (%)a | 1.7 (1.8) | 1.5 (1.1) | 1.7 (1.8) | .87‡ | 2.0 (2.1) | 1.6 (1.7) | .26‡ |
| Diet | |||||||
| Current breast feeding | 85 (58.6) | 10 (71.4) | 75 (57.3) | .31 | 28 (73.7) | 57 (53.3) | .03 |
| Ever fed with formula | 120 (82.8) | 6 (42.9) | 114 (87.0) | <.01 | 22 (57.9) | 98 (91.6) | <.01 |
| Ever fed with solid food | 23 (15.9) | 3 (21.4) | 20 (15.3) | .47 | 7 (18.4) | 16 (15.0) | .62 |
Abbreviations: Ig, immunoglobulin; RBEL II, RSV Bronchiolitis in Early Life II; SD, standard deviation.
*Data are expressed as proportion of children in each vitamin D range except as noted.
†Data represent the mean (SD) of this covariate.
‡Significance level for differences in means was calculated after logarithmic transformation to improve normality of the data.