Work Ability Score, sick leave, respiratory symptom score and % of predicted FEV1, FVC and FEV1/FVC-ratio prebronchodilator and postbronchodilator, stratified by physician-diagnosed asthma and BMI category†‡
Outcome, summary statistics | BMI category | P values for elevated vs normal weight within asthma strata | |||
| Normal weight (BMI <25 kg/m2) | Overweight (BMI 25–29.9 kg/m2) | Obesity (BMI ≥30 kg/m2) | Overweight vs normal | Obesity vs normal | |
| Work ability score <8, n/n total in group (%) | |||||
| No asthma | 46/308 (15%) | 36/250 (14%) | 23/125 (18%) | 0.86 | 0.37 |
| Asthma | 45/223 (20%) | 65/223 (29%) | 46/166 (27%) | 0.03 | 0.08 |
| P values for asthma vs no asthma within BMI categories | 0.11 | >0.001 | 0.07 | ||
| Sick leave in the last 12 months, n/n total in group (%) | |||||
| No asthma | 87/269 (32%) | 69/230 (30%) | 41/111 (37%) | 0.57 | 0.39 |
| Asthma | 74/193 (38%) | 80/202 (40%) | 62/138 (45%) | 0.80 | 0.23 |
| P values for asthma vs no asthma within BMI categories | 0.18 | 0.04 | 0.20 | ||
| Sick leave >14 days, n/n total in group (%) * | |||||
| No asthma | 37/85 (43%) | 29/69 (42%) | 18/41 (44%) | 0.85 | 0.97 |
| Asthma | 39/74 (53%) | 42/80 (53%) | 34/62 (55%) | 0.98 | 0.80 |
| P values for asthma vs no asthma within BMI categories | 0.25 | 0.20 | 0.28 | ||
| Symptom score ≥3, n/n total in group (%) | |||||
| No asthma | 35/309 (11%) | 25/255 (10%) | 26/127 (21%) | 0.60 | 0.01 |
| Asthma | 109/228 (48%) | 107/230 (47%) | 101/168 (60%) | 0.78 | 0.02 |
| P values for asthma vs no asthma within BMI categories | >0.001 | >0.001 | >0.001 | ||
| Symptom score, mean (SEM) | |||||
| No asthma | 1.04 (0.10) | 0.98 (0.11) | 1.57 (0.19) | 0.70 | 0.01 |
| Asthma | 3.46 (0.18) | 3.37 (0.19) | 4.15 (0.23) | 0.75 | 0.02 |
| P values for asthma vs no asthma within BMI categories | >0.001 | >0.001 | >0.001 | ||
| Pre-FEV1 % of predicted value, mean (SEM) | |||||
| No asthma | 98.6 (0.68) | 100.2 (0.77) | 95.4 (1.27) | 0.13 | 0.01 |
| Asthma | 92.9 (0.93) | 93.1 (1.01) | 87.8 (1.30) | 0.97 | >0.001 |
| P values for asthma vs no asthma within BMI categories | >0.001 | >0.001 | >0.001 | ||
| Pre-FVC % of predicted value, mean (SEM) | |||||
| No | 100.9 (0.62) | 102.0 (0.76) | 96.5 (1.17) | 0.37 | >0.001 |
| Yes | 100.4 (0.82) | 98.1 (0.82) | 93.6 (1.10) | 0.04 | >0.001 |
| P values for asthma vs no asthma within BMI categories | 0.59 | 0.001 | 0.08 | ||
| Pre-FEV1/FVC-ratio in %, mean (SEM) | |||||
| No asthma | 79.7 (0.39) | 79.3 (0.35) | 79.8 (0.47) | 0.54 | 0.82 |
| Asthma | 76.3 (0.54) | 76.4 (0.50) | 75.7 (0.65) | 0.94 | 0.56 |
| P values for asthma vs no asthma within BMI categories | >0.001 | >0.001 | >0.001 | ||
| Post-FEV1 % of Post-FEV1 % of predicted value, mean (SEM)predicted value, mean (SEM) | |||||
| No asthma | 101.0 (0.70) | 102.3 (0.82) | 97.4 (1.43) | 0.31 | 0.003 |
| Asthma | 96.6 (0.93) | 96.0 (0.97) | 93.2 (1.30) | 0.81 | 0.02 |
| P values for asthma vs no asthma within BMI categories | >0.001 | >0.001 | 0.03 | ||
| Post-FVC % of predicted value, mean (SEM) | |||||
| No asthma | 100.4 (0.66) | 101.5 (0.82) | 95.9 (1.25) | 0.38 | >0.001 |
| Asthma | 100.4 (0.86) | 98.7 (0.82) | 95.9 (1.14) | 0.20 | 0.001 |
| P values for asthma vs no asthma within BMI categories | 0.99 | 0.02 | 0.99 | ||
| Post-FEV1/FVC ratio in %, mean (SEM) | |||||
| No asthma | 82.1 (0.42) | 81.2 (0.36) | 82.0 (0.51) | 0.12 | 0.59 |
| Asthma | 79.4 (0.55) | 78.5 (0.49) | 78.5 (0.66) | 0.26 | 0.31 |
| P values for asthma vs no asthma within BMI categories | >0.001 | >0.001 | >0.001 | ||
Prebronchodilator spirometry: 661 acceptable tests among controls, 596 acceptable tests among cases.
Postbronchodilator spirometry: 559 acceptable tests among controls, 532 acceptable tests among cases.
Statistically significant findings are given in bold.
*The participants with reported sick leave >14 days were limited to those who reported taking sick leave in the last 12 months.
†P values were based on χ2 test for categorical variables and one-way ANOVA for continuous variables.
‡The distribution by BMI category for all 691 participants without asthma was 269 normal weight, 230 overweight and 111 obese; for all 626 participants with asthma, 193 had normal weight, 202 had overweight and 138 had obese. The actual numbers varied by outcome variable, depending on the number of missing values.
ANOVA, Analysis of variance; BMI, body mass index; FEV, forced expiratory volume; FEV1, forced expiratory volume after 1 s; FVC, forced vital capacity.