Table 2.
Multilevel model analysis of the association between individual and walkability and lung function, pH, exhaled NO and pupillometry parameters explained by school.
| Outcome | Walkabilityβ (95% CI) | School | ||
|---|---|---|---|---|
| ICC | Variance | Explained variation* | ||
| FVC | ||||
| Model 0 | −0.58 (−2.79; 1.63) | — | — | — |
| Model 1 | — | 1.78% | 4.48 | Reference |
| Model 5a | −2.62 (−6.00; 0.77) | 1.32E-6% | 2.51E-6 | >99.9% |
| FEV 1 | ||||
| Model 0 | −1.02 (−3.07; 1.02) | — | — | — |
| Model 1 | — | 2.09% | 4.53 | Reference |
| Model 5a | −2.63 (−5.71; 0.46) | 4.47E-7% | 7.09E-7 | >99.9% |
| FEF 25%-75% | ||||
| Model 0 | −1.27 (−4.74; 1.98) | — | — | — |
| Model 1 | — | 0.37% | 2.14 | Reference |
| Model 5a | −0.72 (−6.33; 4.89) | 5.27E-7 | 2.77E-6 | >99.9% |
| EBC pH | ||||
| Model 0 | 0.09 (−0.03; 0.21) | — | — | — |
| Model 1 | — | 3.48% | 0.03 | Reference |
| Model 5a | −0.004 (−0.34; 0.33) | 8.52% | 0.08 | >−99.9% |
| Exhaled NO | ||||
| Model 0 | −0.05 (−0.17; 0.07) | — | — | — |
| Model 1 | — | 3.98% | 0.03 | Reference |
| Model 5b | −0.07 (−0.38; 0.23) | 8.07% | 0.06 | −90.6% |
| Baseline pupil diameter | ||||
| Model 0 | −0.22 (−0.34; −0.09) | — | — | — |
| Model 1 | — | 20.4% | 0.158 | Reference |
| Model 5c | −0.18 (−0.54; 0.17) | 22.1% | 0.178 | −12.5% |
| Final pupil diameter | ||||
| Model 0 | −0.04 (−0.13; 0.05) | — | — | — |
| Model 1 | — | 14.1% | 0.053 | Reference |
| Model 5c | −0.05 (−0.26; 0.16) | 15.1% | 0.059 | −10.3% |
| ACV | ||||
| Model 0 | −0.22 (−0.32; −0.12) | — | — | — |
| Model 1 | — | 14.7% | 0.070 | Reference |
| Model 5c | −0.21 (−0.46; 0.03) | 16.7% | 0.081 | −16.4% |
| MCV | ||||
| Model 0 | −0.31 (−0.45; −0.17) | — | — | — |
| Model 1 | — | 12.3% | 0.112 | Reference |
| Model 5c | −0.29 (−0.60; 0.02) | 10.1% | 0.091 | 18.0% |
| Constriction amplitude | ||||
| Model 0 | −1.94 (−2.65; −1.23) | — | — | — |
| Model 1 | — | 8.38% | 2.073 | Reference |
| Model 5c | −1.62 (−2.87; −0.37) | 7.52% | 1.847 | 10.9% |
| ADV | ||||
| Model 0 | 0.01 (−0.04; 0.06) | — | — | — |
| Model 1 | — | 8.57E-8% | 8.10E-11 | Reference |
| Model 5c | 0.005 (−0.06; 0.07) | 7.82E-8% | 7.48E-11 | 7.60% |
| T75 | ||||
| Model 0 | −0.17 (−0.29; −0.06) | — | — | — |
| Model 1 | — | 4.53% | 0.023 | Reference |
| Model 5c | −0.19 (−0.36; −0.02) | 3.19% | 0.016 | 29.3% |
*corresponds to the proportion of between-schools variance that could be explained by exposure and individual characteristics; 95% CI: 95% confidence interval; ICC: intra-class correlation coefficient; FVC: forced vital capacity; FEV1: forced expiratory volume in the first second of FVC; FEF25–75: forced expiratory flow in the middle portion of FVC; EBC: Exhaled breath condensate; ACV: Average constriction velocity; MCV: Maximum constriction velocity; ADV: Average dilation velocity; T75: the total time taken by the pupil to recover 75% of its initial resting diameter after it reached the peak of constriction.
Model 0 only included the PC1 and PC2 score; a Model 1 is null model, baseline model without any exposure variable; Model 5a is additionally adjusted for age, sex, asthma, WHO z-score for BMI and family history of asthma or allergy; Model 5a is additionally adjusted for age, sex, asthma, atopy, WHO z-score for BMI and family history of asthma or allergy; Model 5c is additionally adjusted for age, sex, asthma, and WHO z-score for BMI.