Table 1 Descriptive comparisons between cases and controls in male and female children: figures shown for cases and controls are mean (s.d.) or number (%)
Variables | Males | Females | ||||
|---|---|---|---|---|---|---|
Cases (n=388) | Controls (n=388) | Differences for the mean or for rates between cases and controls (95% CI) | Cases (n=244) | Controls (n=244) | Differences for the mean or for rates between cases and controls (95% CI) | |
Measures of obesity | ||||||
Primary measures mean (s.d.) | ||||||
BMI (kg/m2) | 17.0 (3.8) | 15.8 (2.5) | 1.2 (+0.7, +1.7)a | 19.0 (4.4) | 15.9 (2.1) | 3.1 (+2.5, +3.7)a |
Secondary measures mean (s.d.) | ||||||
TSFT (mm) | 10.5 (4.2) | 9.2 (3.3) | 1.3 (+0.8, +1.8)a | 13.8 (5.3) | 10.5 (3.2) | 3.3 (+2.6,+4.1)a |
WC (cm) | 56.6 (8.8) | 53.6 (6.4) | 3 (+1.9, +4.0)a | 61.0 (10.1) | 53.9 (5.8) | 7.1 (+5.6, +8.4)a |
Weight (kg) | 26.1 (8.0) | 23.9 (5.7) | 2.2 (+1.2, +3.2)a | 30.4 (9.6) | 24.1 (5.4) | 6.3 (+4.92, +7.69)a |
Explanatory variables | ||||||
Lung function measures | ||||||
FVC (Lt) mean (s.d.) | 1.35 (0.36) | 1.46 (0.37) | −0.11 (−0.16, −0.06)a | 1.17 (0.31) | 1.22 (0.30) | −0.05 (−0.10, +0.00) |
FEV1 (Lt) mean (s.d.) | 1.15 (0.30) | 1.31 (0.34) | −0.16 (−0.21, −0.12)a | 0.96 (0.27) | 1.08 (0.28) | −0.12 (−0.17, −0.08)a |
PEFR (Lt) mean (s.d.) | 2.40 (0.64) | 2.72 (0.56) | −0.32 (−0.41, −0.24)a | 1.77 (0.76) | 2.36 (0.57) | −0.59 (−0.70, −0.47)a |
Sensitisation to one or more allergens (⩾3 mm), n (%) | ||||||
Cat | 216 (56) | 55 (14) | 42 (+36.0, +48.0)a | 166 (68) | 35 (14) | 54 (+46.7, +61.3)a |
Dermatophagoides farinae | 99 (25) | 21 (5) | 20 (+15.2, +24.8)a | 79 (32) | 6 (2) | 30 (+23.9, +36.1)a |
Dermatophagoides pteronyssinus | 99 (25) | 11 (3) | 22 (+17.4, +26.6)a | 91 (37) | 16 (6) | 31 (+24.3, +37.8)a |
Grass mix | 66 (17) | 14 (4) | 13 (+8.8, +17.2)a | 51 (21) | 5 (2) | 19 (+13.6, +24.4)a |
Rye | 55 (14) | 15 (4) | 10 (+6.0, +14.0)a | 83 (34) | 2 (1) | 33 (+26.9, +39.1)a |
Tree mix (early blossoming) | 70 (18) | 13 (3) | 15 (+10.8, +19.2)a | 89 (36) | 4 (2) | 32 (+27.7, +40.3)a |
Tree mix (mid-blossoming) | 80 (21) | 18 (5) | 16 (+11.4, +20.6)a | 81 (33) | 3 (1) | 30 (+26.0, +38.0)a |
Weed mix | 62 (16) | 10 (3) | 13 (+9.0, +17.0)a | 66 (27) | 7 (2) | 20 (+19.2, +30.8)a |
Sensitisation to 1⩾allergen | 325 (84) | 107 (27) | 57 (+51.3, +62.7)a | 234 (96) | 54 (22) | 74 (+68.2, +79.8)a |
Potential confounders | ||||||
Father’s age (years) mean (s.d.) | 43.3 (8.4) | 42.1 (7.8) | 1.12 (−0.04, +2.28) | 44.1 (9.0) | 44.8 (8.9) | 0.1 (−5.0, +5.2) |
Mother’s age (years) mean (s.d.) | 35 (6.1) | 34.6 (6.2) | 0.36 (−0.51, +1.23) | 36.2 (6.0) | 36.1 (6.1) | −0.1 (−4.3, +4.1) |
Birth weight (kg) mean (s.d.) | 2.90 (0.66) | 3.00 (0.58) | −0.10 (−0.20, −0.01)a | 2.94 (0.67) | 2.83 (0.62) | 0.11 (−0.02, +0.24) |
Father’s education (highest qualification), n (%) | ||||||
None | 14 (3.7) | 21 (5.6) | −1.9 (−4.9, +1.1) | 22 (9.4) | 14 (5.9) | 3.5 (−1.2, +8.2) |
General education | 192 (50.8) | 198 (53.2) | −2.4 (−1.0, +4.0) | 132 (56.2) | 156 (65.3) | −9.1 (−8.9, +8.7) |
Higher education | 172 (45.5) | 153 (41.1) | 4.4 (−3.0, +11.0) | 81 (34.5) | 69 (28.9) | 5.6 (−2.6, +13.6) |
Mother’s education (highest qualification), n (%) | ||||||
None | 14 (3.7) | 32 (8.3) | −4.6 (−7.9, −1.3)a | 26 (10.9) | 29 (12.0) | −1.1 (−6.7, +4.5) |
General education | 208 (54.5) | 205 (53.4) | 1.1 (−5.9, +8.1) | 141 (59.0) | 144 (59.8) | −0.8 (−9.5, +7.9) |
Higher education | 160 (41.9) | 147 (38.3) | 3.6 (−3.3, +10.5) | 72 (30.1) | 68 (28.2) | 1.9 (−6.2, +10) |
Father smoker, n (%) | ||||||
Yes | 129 (33.3) | 96 (24.8) | 8.5 (+2.1, +14.9)a | 56 (23.1) | 77 (31.8) | −8.7 (−16.6, −0.8)a |
No | 258 (66.7) | 291 (75.2) | −8.5 (−14.9, −2.1)a | 186 (76.9) | 168 (68.2) | 8.7 (+0.8, +16.6)a |
Mother smoker, n (%) | ||||||
Yes | 5 (1.3) | 1 (0.3) | 1.0 (−0.25, +2.25) | 4 (1.7) | 2 (0.8) | 0.9 (−1.1, +2.9) |
No | 382 (98.7) | 385 (99.7) | −1.0 (−2.3, +0.3) | 236 (98.3) | 241 (99.2) | −0.9 (−2.9, +1.1) |
Birth order, n (%) | ||||||
First child | 206 (53.4) | 206 (53.1) | 0.3 (−6.7, +7.3) | 43 (17.8) | 47 (19.5) | −1.7 (−8.6, +5.2) |
Second child | 125 (32.4) | 123 (31.7) | 0.7 (−5.9, +7.3) | 189 (78.1) | 180 (74.7) | 3.4 (−4.1, +10.9) |
Third or greater | 55 (14.2) | 56 (15.2) | −1.0 (−6.0, +4.0) | 10 (4.1) | 14 (5.8) | −1.7 (−5.5, +2.1) |
Was the child born in Madinah?, n (%) | ||||||
Yes | 332 (85.8) | 328 (85.4) | 0.4 (−4.5, +5.3) | 202 (84.5) | 200 (82.6) | 1.9 (−4.7, +8.5) |
No | 55 (14.2) | 56 (14.6) | −0.4 (−5.3, +4.5) | 37 (15.5) | 42 (17.4) | −1.9 (−8.5, +4.7) |
Did the mother breastfeed?, n (%) | ||||||
Yes | 290 (75.9) | 330 (85.5) | −9.6 (−15.1, −4.1)a | 208 (86.7) | 193 (80.1) | 6.6 (0.0, +13.0) |
No | 92 (24.1) | 56 (14.5) | 8.5 (+2.1, +14.9)a | 32 (13.3) | 48 (19.9) | −8.7 (−16.6, −0.8)a |
Medication given in the 1st year of child’s life, n (%) | ||||||
Paracetamol | 367 (95.6) | 329 (88.4) | 7.2 (+3.4, +11.0)a | 213 (89.9) | 209 (87.4) | 2.5 (−3.1, +8.1) |
Antibiotics | 311 (82.3) | 213 (57.9) | 24.4 (+18.2, +30.6)a | 164 (69.5) | 148 (61.7) | 7.8 (−0.6, +16.2) |
Paracetamol administered in the last 12 months, n (%) | ||||||
Once a week at least | 87 (22.9) | 70 (18.9) | 4.0 (−1.7, +9.7) | 54 (22.9) | 39 (16.9) | 6.0 (−1.1, +13.1) |
Once a month at least | 220 (57.9) | 195 (52.7) | 5.2 (−1.8, +12.2) | 135 (57.2) | 125 (54.1) | 3.1 (−5.7, +11.9) |
Once a year at least | 73 (19.2) | 105 (28.4) | −9.2 (−15.2, −3.2)a | 47 (19.9) | 67 (29.0) | −9.1 (−16.7, −1.5)a |
Exposure to animals, n (%) | ||||||
Farm animal when mother was pregnant | 11 (2.9) | 11 (2.9) | 0.0 (−2.4, +2.4) | 14 (6.1) | 8 (3.4) | 2.7 (−1.1, +6.5) |
Cat at home in the 1st year of child’s life | 15 (3.9) | 15 (3.9) | 0.0 (−2.7, +2.7) | 19 (7.9) | 6 (2.5) | 5.4 (+1.5, +9.3)a |
Cat at home in the last 12 months | 29 (7.5) | 25 (6.5) | 1.0 (−2.6, +4.6) | 18 (7.5) | 12 (5.0) | 2.5 (+1.2, +8.8)a |
Farm animal in the 1st year of child life | 24 (6.2) | 16 (4.2) | 2.0 (−1.1, +5.1) | 16 (6.8) | 5 (2.1) | 4.7 (+1.1, +8.3)a |
Taking exercise per week, n (%) | ||||||
Never | 241 (64.3) | 254 (68.8) | −4.5 (−11.1, +2.1) | 201 (85.5) | 200 (86.2) | −0.7 (−6.9, +5.5) |
Once or twice a week | 101 (26.9) | 86 (23.3) | 3.6 (−2.5, +9.7) | 31 (13.2) | 25 (10.8) | 2.4 (−3.4, +8.2) |
Three or more a week | 33 (8.8) | 29 (7.9) | 0.9 (−3.0, +4.8) | 3 (1.3) | 7 (3.0) | −1.7 (−4.3, +0.9) |
Watching TV, n (%) | ||||||
<3 h per day | 228 (60.0) | 241 (64.6) | −4.6 (−11.4, +2.2) | 137 (56.8) | 128 (54.9) | 1.9 (−6.9, +10.7) |
>3 h per day | 152 (40.0) | 132 (35.4) | 4.6 (−2.2, +11.4) | 104 (43.2) | 105 (45.1) | −1.9 (−10.7, +6.9) |
What is the fuel normally used in cooking in your household?, n (%) | ||||||
Electricity only | 20 (5.2) | 20 (5.2) | 0 (−3.1, +3.1) | 9 (3.8) | 15 (6.3) | −2.5 (−6.4, +1.4) |
Gas only | 351 (90.9) | 349 (90.4) | 0.5 (−3.6, +4.6) | 223 (92.9) | 220 (92.4) | 0.5 (−4.1, +5.1) |
Both electricity & gas | 15 (3.9) | 17 (4.4) | −0.5 (−3.3, +2.3) | 8 (3.3) | 3 (1.3) | 2.0 (−0.7, +4.7) |
Air conditioning type, n (%) | ||||||
Electric fan only | 3 (0.8) | 1 (0.3) | 0.5 (−0.54, +1.54) | 1 (0.4) | 2 (0.8) | −0.4 (−1.77, +0.97) |
Water system only | 4 (1.0) | 5 (1.3) | −0.3 (−1.8, +1.2) | 4 (1.7) | 10 (4.1) | −2.4 (−5.4, +0.6) |
Freon system only | 365 (94.3) | 372 (96.6) | −2.3 (−5.2, +0.6) | 194 (82.2) | 223 (92.5) | −10.3 (−16.1, −4.5)a |
Both Freon & water systems | 15 (3.9) | 7 (1.8) | 2.1 (−0.2, +4.4) | 37 (15.7) | 6 (2.5) | 13.2 (+8.2, +18.2)a |
How often does a truck pass through the street adjacent to your home?, n (%) | ||||||
Rarely | 237 (61.6) | 268 (70.9) | −9.3 (−15.9, −2.7)a | 168 (70.3) | 169 (70.7) | −0.4 (−8.5, +7.7) |
Frequently | 148 (38.4) | 110 (29.1) | 9.3 (+2.7, +15.9)a | 71 (29.7) | 70 (29.3) | 0.4 (−7.7, +8.5) |
Diet—How many times a week does your child eat the following?, n (%) | ||||||
Meats | ||||||
Never | 20 (5.2) | 16 (4.2) | 1.0 (−4.0, +2.0) | 9 (3.7) | 26 (10.9) | −7.2 (−11.8, −2.6)a |
Once or twice a week | 110 (28.6) | 122 (31.8) | −3.2 (−9.7, +3.3) | 83 (34.2) | 81 (33.9) | 0.3 (−8.1, +8.7) |
Three or more a week | 254 (66.1) | 246 (64.1) | 2.0 (−4.7, +8.7) | 151 (62.1) | 132 (55.2) | 6.9 (−1.8, +15.6) |
Fruits | ||||||
Never | 68 (17.7) | 44 (11.5) | 6.2 (−6.9, +19.3) | 29 (12.0) | 24 (10.0) | 2.0 (−3.5, +7.5) |
Once or twice a week | 167 (43.4) | 175 (45.9) | −2.5 (−9.5, +4.5) | 114 (47.1) | 115 (48.1) | −1.0 (−9.9, +7.9) |
Three or more a week | 150 (39.0) | 162 (42.5) | −3.5 (−10.4, +3.4) | 99 (40.9) | 100 (41.8) | −0.9 (−9.6, +7.8) |
Rice | ||||||
Never | 9 (2.4) | 8 (2.1) | 0.3 (−1.8, +2.4) | 6 (2.5) | 10 (4.2) | −1.7 (−4.9, +1.5) |
Once or twice a week | 70 (18.4) | 83 (21.7) | −3.3 (−8.9, +2.3) | 45 (19.0) | 47 (19.7) | −0.7 (−7.7, +6.3) |
Three or more a week | 301 (79.2) | 291 (76.2) | 3.0 (−2.9, +8.9) | 186 (78.2) | 182 (76.2) | 2.0 (−5.4, +9.4) |
Nuts | ||||||
Never | 224 (59.4) | 227 (60.7) | −1.3 (−8.2, +5.6) | 151 (62.9) | 116 (50.0) | 12.9 (+4.2, +21.6)a |
Once or twice a week | 134 (35.5) | 118 (31.6) | 3.9 (−2.7, +10.5) | 73 (30.4) | 93 (40.1) | −9.7 (−18.1,−1.3)a |
Three or more a week | 19 (5.0) | 29 (7.8) | −2.8 (−6.2, +0.6) | 16 (6.7) | 23 (9.9) | −3.2 (−8.1, +1.7) |
Fast food | ||||||
Never | 217 (56.7) | 225 (59.2) | −2.5 (−9.4, +4.4) | 160 (67.5) | 164 (69.8) | −2.3 (−10.5, +5.9) |
Once or twice a week | 132 (34.5) | 122 (32.1) | 2.4 (−4.2, +9.0) | 60 (25.3) | 56 (23.8) | 1.5 (−6.1, +9.1) |
Three or more a week | 34 (8.9) | 33 (8.7) | 0.2 (−3.8, +4.2) | 17 (7.2) | 15 (6.4) | 0.8 (−3.7, +5.3) |
