TABLE 1.
CHARACTERISTICS OF STUDY PARTICIPANTS
| Quartiles of Vitamin D
|
||||||
|---|---|---|---|---|---|---|
| Characteristics | All Children* | 1st Quartile† (12.5–29.0) | 2nd Quartile (29.1–35.7) | 3rd Quartile (35.8–43.0) | 4th Quartile (43.1–98.1) | P Value for Trend‡ |
| Participants, no. | 616 | 154 | 156 | 152 | 154 | |
| Age, years | 8.7 (7.6–10.5) | 9.3 | 9.3 | 8.7 | 8.9 | 0.008 |
| Female sex | 246 (40%) | 71 (46%) | 65 (42%) | 55 (36%) | 55 (36%) | 0.04 |
| BMI | 16.9 (15.5–19.5) | 18.2 | 18.3 | 17.5 | 17.5 | 0.02 |
| Total IgE, IU/ml | 392 (114–932) | 810 | 737 | 624 | 618 | 0.03 |
| Eosinophil count, cells/mm3 | 520 (270–790) | 634 | 588 | 605 | 552 | 0.14 |
| Prebronchodilator lung function | ||||||
| FEV1, L | ||||||
| Absolute | 1.68 (1.42–1.99) | 1.8 | 1.8 | 1.7 | 1.7 | 0.03 |
| Predicted§ | 1.70 (1.40–2.04) | 1.9 | 1.8 | 1.7 | 1.7 | |
| FVC, L | 2.0 (1.7–2.4) | 2.2 | 2.2 | 2.1 | 2.0 | 0.01 |
| FEV1/FVC ratio | 83% (79–87) | 82% | 83% | 83% | 82% | 0.51 |
| Maternal history of asthma | 188 (31%) | 48 (31%) | 45 (29%) | 47 (31%) | 48 (31%) | 0.91 |
| Paternal history of asthma | 138 (23%) | 39 (26%) | 36 (23%) | 32 (21%) | 31 (20%) | 0.21 |
| Health care use | ||||||
| Hospitalizations for asthma in the previous year | 35 (5.7%) | 11 (7%) | 6 (4%) | 14 (9%) | 4 (3%) | 0.32 |
| Unscheduled visits for asthma in the previous year | 562 (91%) | 136 (88%) | 140 (89%) | 142 (93%) | 144 (94%) | 0.26 |
| Absolute bronchodilator response, ml | 70 (10–150) | 109 | 98 | 79 | 72 | 0.01 |
| Use of antiinflammatory medication in the last year‖ | 238 (39%) | 66 (43%) | 64 (41%) | 51 (34%) | 57 (36%) | 0.15 |
| Allergen-specific IgE responses¶ | ||||||
| Positive IgE to Ascaris | 234 (38%) | 59 (38%) | 60 (39%) | 51 (34%) | 64 (42%) | 0.78 |
| Positive IgE to Der p | 463 (75%) | 119 (77%) | 120 (77%) | 113 (74%) | 111 (72%) | 0.24 |
| Positive IgE to Bla g | 243 (40%) | 65 (42%) | 67 (43%) | 45 (30%) | 66 (43%) | 0.52 |
| Skin test reactivity** | ||||||
| Dust mite | 494 (81%) | 126 (82%) | 126 (81%) | 118 (78%) | 124 (81%) | 0.57 |
| Cockroach | 356 (58%) | 90 (59%) | 90 (58%) | 84 (56%) | 92 (60%) | 0.96 |
| Outdoor allergens†† | 119 (19%) | 33 (22%) | 32 (21%) | 23 (15%) | 31 (20%) | 0.51 |
Definition of abbreviations: Bla g = Blatella germanica; BMI = body mass index; Der p = Dermatophagoides pteronyssinus.
Decimal values were approximated to the closest integer for ease of exposition.
Values are given as median (interquartile range) for continuous variables or as number (%) for binary variables.
Values for quartiles are the mean of the subgroup for continuous variables, and the number (%) for binary variables. Vitamin D levels are expressed as nanograms per milliliter.
The Cochran-Armitage trend test was calculated for binary variables, and linear regression was used to calculate a trend test for continuous variables.
Predicted values are for Mexican Americans from Hankinson and colleagues (42).
Includes the use of inhaled corticosteroids and/or leukotriene inhibitors.
Allergen-specific IgE level ≥ 0.35 IU/ml.
Skin test was reactive if the maximal diameter of the wheal was 3 mm after subtraction of the maximal diameter of the negative control.
Outdoor allergens include mixed grass pollen, mixed tree pollen, and Alternaria tenuis.