Cross-sectional and case-controls studies: vitamin D and acute wheeze in preschool children with wheeze
| Author | Sample size | Age range (months) | Setting | Phenotype of wheeze (n) | Subtype of wheeze (n %) | Confounding variables | Main finding |
| Beigelman et al 54 | 278 | 12–53 | USA | Recurrent wheeze and at least four episodes of acute wheezing illness (278) | Positive to at least one allergen (58.4%) | Race, tobacco smoke exposure | Vitamin D deficiency (25(OH)D <50 nmol/L) was associated with higher mean rate of acute episodes of wheezing illness requiring oral corticosteroids compared with vitamin D sufficiency (25(OH)D ≥50 nmol/L) (1.46 vs 0.93 attacks/child-year, p=0.035; rate ratio 1.56 (95% CI 1.03 to 2.37) |
| Uysalol et al 55 | 148 | 3–24 | Turkey | Recurrent wheeze and at least one wheeze attack (73) | Allergic rhinitis and atopic dermatitis | Not reported | Lower 25(OH)D concentration was associated with increased frequency of severe wheeze attacks (p=0.011) and hospitalisations (p=0.026) |
| Healthy controls (75) | |||||||
| Stenberg Hammar et al 57 | 231 | 6–48 | Sweden | Wheeze group (130) | Positive to at least one airborne or food allergen (not reported) | Age, sex, ethnicity, sampling month, >6 respiratory infections a year, history of respiratory syncytial infection | Vitamin D insufficiency (25(OH)D <75 nmol/L) was associated with higher risk for acute episodes of wheezing illness (OR, 95%; 2.7 CI 1.1 to 6.2, p=0.02) |
| Healthy controls (101) | None | ||||||
| Turkeli et al 56 | 204 | 1–4* | Turkey | Mild to moderate asthma (102) | Not reported | Not reported | Number of wheeze attacks significantly lower in the vitamin D sufficient group (25(OH)D >75 nmol/L) compared with the deficient group (25(OH)D ≤50 nmol/L) and the insufficient group (25(OH)D: 50–75 nmol/L) p=0.03 for comparison of vitamin D sufficient group against vitamin D insufficient and deficient |
| 1–4* | Healthy controls (102) |
*Age in years