Table 1.
Characteristics of cases and controls with respect to study variables
| Variable | Cases (N = 60) | Controls (N = 119) | p value |
|---|---|---|---|
| Demographics | |||
| Age, median (IQR) | 9 (6–11) | 10 (7–12) | 0.226 |
| Sex, Male (%) | 31 (52) | 63 (53) | 0.876 |
| Ethnicity (%) | |||
| Afro‐Ecuadorian | 18 (30) | 31 (26) | 0.814 |
| Mestizo or othera | 42 (70) | 86 (74) | |
| Socioeconomic | |||
| Monthly income, median (IQR) | 500 (224–800) | 300 (200–500) | 0.004 |
| Cash transferb (%) | 12 (20) | 53 (45) | 0.002 |
| Parental school yearsc, Median (IQR) | 26 (24–30) | 21 (18–24) | <0.001 |
| Early childhood exposures | |||
| Birthweight (%) | |||
| Low (<2.5 kg) | 11 (26) | 6 (9) | 0.101 |
| Normal | 32 (74) | 60 (91) | |
| Breastfed (%) | 60 (100) | 115 (98) | 0.552 |
| Contact with pets, 1st year (%) | 33 (55) | 63 (53) | 0.874 |
| Contact with farm animals, 1st year (%) | 5 (8) | 10 (9) | 1.000 |
| Air conditioningd, 1st year (%) | 4 (7) | 1 (1) | 0.044 |
| Carpeting, 1st yeard (%) | 13 (22) | 5 (4) | 0.001 |
| Humid householde, 1st year (%) | 19 (32) | 38 (33) | 1.000 |
| Bronchiolitis (%) | 38 (63) | 16 (14) | <0.001 |
| Day care attendance before 4 years | 12 (20) | 38 (32) | 0.112 |
| Current exposures | |||
| Parental asthma (%) | 27 (45) | 28 (24) | 0.006 |
| Birth order, median (IQR) | 2 (1–3) | 2 (1–4) | 0.114 |
| Contact with pets (%) | 42 (70) | 109 (92) | <0.001 |
| Contact with farm animals (%) | 8 (13) | 14 (12) | 0.815 |
| Household ETS | 9 (15) | 29 (24) | 0.177 |
| Humid housee (%) | 19 (32) | 45 (38) | 0.510 |
| Air conditioningd (%) | 6 (10) | 5 (4) | 0.185 |
| Carpetingd (%) | 8 (13) | 12 (10) | 0.616 |
| Intestinal helminths (%) | 1 (2) | 6 (8) | 0.419 |
| Rhinovirus infection (%) | 21 (36) | 8 (8) | <0.001 |
| Nutritional status | |||
| BMI, median (IQR) | 16.1 (15.0–18.7) | 16.9 (15.4–19.8) | 0.184 |
| Hematocrit, median (IQR) | 40 (38–43) | 40 (38–41) | 0.125 |
| Allergic parameters | |||
| Eosinophil counts, median (IQR) | 298 (128–515) | 263 (93–506) | 0.532 |
| SPT, any allergen (%) | 41 (68) | 26 (22) | <0.001 |
| asIgE, any allergen (%) | 49 (82) | 49 (43) | <0.001 |
| Total IgE [kU/l], median (IQR) | 837 (267–1264) | 204 (67–672) | <0.001 |
| Airways function/ inflammation | |||
| FEV1/FVC (IQR) | 0.83 (0.77–0.88) | 0.88 (0.85–0.93) | <0.001 |
| Reversibility with B2 agonist (%) | 13 (28) | 7 (10) | 0.012 |
| Alveolar NO (ppb), median (IQR)f | 13.0 (10.0–21.6) | 12.4 (7.7–17.9) | 0.196 |
| Bronchial NO flux (pl/sec), median (IQR) f | 649 (300–1097) | 317 (−16–652) | 0.004 |
BMI, body mass index; IQR, interquartile range; ETS, exposure to tobacco smoke; SPT, skin prick test; asIgE, allergen‐specific IgE; FEV1, forced expiratory volume in the first second; FVC, forced vital capacity; NO, nitric oxide. Missing data: parental school years (10), monthly income (1), birthweight (70), breastfeeding (1), contact with farm animals 1st year (3), humidity in household 1st year (3), bronchiolitis (1), day care attendance (1), parental asthma (1), birth order (2), contact with farm animals (5), humid house (1), intestinal helminths (60), BMI (17), hematocrit/eosinophil counts (5), SPT (2), asIgE/total IgE (6), FEV1/FVC and reversibility (60), and alveolar NO/bronchial NO flux (57).
Mestizos/whites; cases 41/1; controls 85/3.
Beneficiary of conditional cash transfer program, ‘Bono Solidario’.
Total number of years of school attendance by mother and father.
Anywhere in the house.
Damp spots anywhere in the house.
FeNO parameters were estimated with the measurements at flow rates: 50, 83 and 100 ml/sec, using Hogman method (see Methods).