Table 3.
Distribution of road exposures at birth and pooled road exposures by recurrent wheeze status by age 3 years.
| Road Exposures | Total (n = 920) | Without Recurrent Wheeze by Age 3 Years (n = 624) | With Recurrent Wheeze by Age 3 Years (n = 296) | p-Value * | |
|---|---|---|---|---|---|
| Number of participants who moved, n (%) | 329 (36) | 264 (42) | 65 (22) | <0.001 | |
| Number of moves per participant, median (IQR) | 1 (1–2) | 1 (1–2) | 1 (1–1) | <0.001 | |
| Average length of stay in each address in days, median (IQR) | 548 (355–1095) | 559 (428–1095) | 337 (233–494) | <0.001 | |
| Birth distance to major roads in meter, median (IQR) | 550 (234–1135) | 576 (240–1159) | 474 (207–1067) | 0.30 | |
| Pooled distance to major roads in meter, median (IQR) | 565 (257–1141) | 583 (274–1162) | 526 (238–1078) | 0.31 | |
| Birth distance to primary roads in meters, median (IQR) | 3004 (1290–6273) | 3018 (1277–6326) | 2969 (1333–6206) | 0.97 | |
| Pooled distance to primary roads in meters, median (IQR) | 3266 (1391–7189) | 3345 (1396–7522) | 3120 (1388–6911) | 0.76 | |
| Birth major road density in km roadways/km2 land area, median (IQR) † | 5 (4–9) | 5 (4–9) | 5 (4–9) | 0.63 | |
| Pooled major road density in km roadways/km2 land area, median (IQR) †,§ | 4 (3–7) | 4 (2–7) | 5 (3–8) | 0.04 | |
| Birth primary road density in km roadways/km2 land area, median (IQR) † | 6 (3–11) | 6 (3–9) | 11 (3–17) | 0.14 | |
| Pooled primary road density in km roadways/km2 land area, median (IQR) †,§ | 4 (2–7) | 4 (2–7) | 4 (4–14) | 0.07 | |
| Birth population density in population/mile2 land area, median (IQR) ‡ | 4456 (1795–10,756) | 4174 (1560–10,744) | 5068 (2066–11,325) | 0.64 | |
| Pooled population density in (population/mile2 land area, median (IQR) ‡,§ | 4546 (1935–10,100) | 4486 (1896–10,047) | 5147 (2057–10,603) | 0.93 | |
| Birth distance to major roads, meters | <100 | 85 (9) | 47 (8) | 38 (13) | 0.07 |
| 100–200 | 116 (13) | 82 (13) | 34 (12) | ||
| 201–300 | 86 (9) | 61 (10) | 25 (8) | ||
| >300 | 632 (69) | 433 (70) | 199 (67) | ||
| Birth distance to primary roads, meters | <400 | 59 (6) | 45 (7) | 14 (5) | 0.34 |
| 400–1000 | 114 (12) | 78 (13) | 36 (12) | ||
| >1000 | 746 (81) | 500 (80) | 246 (83) | ||
| Pooled distance to major roads, meters § | <100 | 69 (8) | 37 (6) | 32 (11) | 0.06 |
| 100–200 | 95 (10) | 63 (10) | 32 (11) | ||
| 201–300 | 101 (11) | 69 (11) | 32 (11) | ||
| >300 | 655 (71) | 455 (73) | 200 (67) | ||
| Pooled distance to primary roads, meters § | <400 | 46 (5) | 33 (5) | 13 (4) | 0.81 |
| 400–1000 | 103 (11) | 71 (12) | 32 (11) | ||
| >1000 | 771 (84) | 520 (83) | 251 (85) | ||
Abbreviations: IQR = interquartile range. * All of the p-values obtained by excluding participants with any missing data. † Geographic information systems (GIS) based road measurements were done in a circular buffer area with a 250-radius surrounding the participants’ residential area. ‡ Population density of residential census block was assigned to each participant by weighted block centroid geographic retrieval. § Pooled estimates derived by weighting exposures according to duration spent each address up to age three or time outcome occurred, whichever happened first.