Table 1. Demographic characteristics, lifestyle and clinical features of asthma cases and controls.
| Characteristic | Control (n = 551) | Case (n = 551) | p-valuea |
|---|---|---|---|
| Male, n (%) | 237 (43.01) | 237 (43.01) | |
| Age (years, Mean±SD) | 42.74±12.56 | 42.41±12.80 | 0.3769 |
| Educational level, n (%) | 0.0005 | ||
| Low | 260 (47.19) | 308 (55.90) | |
| Middle | 197 (35.75) | 138 (25.05) | |
| High | 94 (17.06) | 105 (19.06) | |
| Exposure to dust, n (%) | 69 (12.52) | 96 (17.42) | 0.0224 |
| Family history of asthma, n (%) | 11 (2.00) | 62 (11.25) | 0.0001 |
| Tobacco smoking, n (%) | <0.0001 | ||
| Nonsmokers | 392 (71.14) | 434(78.77) | |
| Former smokers | 27 (4.90) | 42(7.62) | |
| Current smokers | 132 (23.96) | 75(13.61) | |
| Physical activity, n (%) | 188 (34.12) | 126 (22.87) | 0.0001 |
| Pet ownership, n (%) | 56 (10.16) | 93 (16.88) | 0.0011 |
| Flower gardening, n (%) | 169 (30.67) | 108 (19.60) | <0.0001 |
| BMI level, n (%) | <0.0001 | ||
| Underweight, <18.5 kg/m2 | 22 (3.99) | 48 (8.71) | |
| Normal weight, 18.5–24 kg/m2 | 267 (48.46) | 309 (56.08) | |
| Overweight, 24–28 kg/m2 | 198 (35.93) | 151 (27.40) | |
| Obese, ≥28 kg/m2 | 64 (11.62) | 43 (7.80) | |
| BMI (kg/m2, Mean±SD) | 24.00±3.66 | 23.13±4.21 | 0.0002 |
| Spirometric indices (Mean±SD) | |||
| FEV1 (L) | 2.54±0.64 | 2.33±0.84 | <0.0001 |
| FEV1(% predicted) | 88.07±13.76 | 82.85±24.00 | <0.0001 |
| FEV1/FVC (%) | 87.90±8.80 | 71.40±14.09 | <0.0001 |
Abbreviation: SD, standard deviation; BMI, body mass index; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity.
aStudent’s t-test for continuous variables and Chi-square test for categorical variables.