Regional variations in risk factors for asthma in school children: RESULTS (2)

Regional variations in risk factors for asthma in school children: RESULTS (2)Unadjusted analysis
The prevalence of asthma was significantly higher in Estevan compared with Swift Current (21.4% versus 16.2%, respectively, crude OR=1.41, 95% CI 1.13 to 1.76). When considering personal characteristics, there were significant associations between asthma and respiratory allergy, early respiratory illness and family history of asthma (Table 3). Indoor characteristics associated with asthma were previous exposure to ETS from the mother, home mould or dampness, and living in a dwelling other than a single-family house (Table 4).

When associations with asthma were examined in each town at the univariate level, associations similar to the overall findings for asthma were found for respiratory allergy, early respiratory illness, family history of asthma and previous exposure to ETS from the mother in both communities. However, the towns differed in certain exposures for asthma — ventolin inhaler. In Swift Current, associations with asthma were found for those of a non-Caucasian ethnicity (OR=2.88, 95% CI 1.03 to 8.05) and gas heating in the home (OR=1.75, 95% CI 1.00 to 3.07).

TABLE 3 Distribution of personal characteristics by asthma

No asthma Asthma
(n=1657), (n=381), OR
n (%) n (%) (95% CI)
Ethnic background
Non-Caucasian 88 (5.3) 15 (3.9)
Caucasian 1569 (94.7) 366 (96.1) 1.37 (0.78-2.39)
Parents with >high school education
No 655 (39.5) 144 (37.8)
Yes 1002 (60.5) 237 (62.2) 1.08 (0.86-1.35)
Living in a two-parent home
No 229 (13.8) 55 (14.4)
Yes 1428 (86.2) 326 (85.6) 0.95 (0.69-1.31)
Report of respiratory allergy
No 1351 (81.5) 126 (33.1)
Yes 306 (18.5) 255 (66.9) 8.94 (6.98-11.44)
Report of early respiratory illness
No 1522 (91.9) 297 (78.0)
Yes 135 (8.1) 84 (22.0) 3.19 (2.36-4.30)
Family history of asthma
No 1512 (91.2) 294 (77.2)
Yes 145 (8.8) 87 (22.8) 3.09 (2.30-4.14)
Birthweight
>2500 g 1552 (93.7) 355 (93.2)
<2500 g 105 (6.3) 26 (6.8) 1.08 (0.69-1.69)
Born premature
No 1388 (83.8) 309 (81.1)
Yes 269 (16.2) 72 (18.9) 1.20 (0.90-1.60)
Breastfed
No 441 (26.6) 97 (25.5)
Yes 1216 (73.4) 284 (74.5) 1.06 (0.82-1.37)
Mean ± SD age (years) 8.7±1.8 8.8±1.7 1.02 (0.96-1.08)

TABLE 4 Distribution of indoor environmental factors by asthma

No asthma (n=1657), n (%) Asthma (n=381), n (%) OR (95% CI)
ETS exposure from mother
Never 997 (60.2) 211 (55.4)
Previous 166 (10.0) 66 (17.3) 1.87 (1.36-2.59)
Current 494 (29.8) 104 (27.3) 1.00 (0.77-1.29)
ETS exposure from father
Never 920 (55.5) 202 (53.0)
Previous 189 (11.4) 56 (14.7) 1.35 (0.97-1.89)
Current 548 (33.1) 123 (32.3) 1.02 (0.80-1.31)
Residence
Urban 1574 (95.0) 356 (93.4)
Rural 83 (5.0) 25 (6.6) 1.33 (0.84-2.11)
Presence of home mould or dampness
No 1300 (78.5) 268 (70.3)
Yes 357 (21.5) 113 (29.7) 1.54 (1.20-1.97)
Ever owned a pet
No 576 (34.8) 126 (33.1)
Yes 1081 (65.2) 255 (66.9) 1.08 (0.85-1.37)
Presence of a home air conditioner
No 629 (38.0) 157 (41.2)
Yes 1028 (62.0) 224 (58.8) 0.87 (0.70-1.10)
Presence of a home air filter
No 1169 (70.5) 260 (68.2)
Yes 488 (29.5) 121 (31.8) 1.12 (0.88-1.42)
Presence of a home humidifier
No 1182 (71.3) 276 (72.4)
Yes 475 (28.7) 105 (27.6) 0.95 (0.74-1.21)
Presence of a home dehumidifier
No 1539 (92.9) 352 (92.4)
Yes 118 (7.1) 29 (7.6) 1.08 (0.70-1.64)
Presence of a home fireplace
No 1145 (69.1) 283 (74.3)
Yes 512 (30.9) 98 (25.7) 0.77 (0.60-1.00)
Gas heating
No 191 (11.5) 36 (9.4)
Yes 1466 (88.5) 345 (90.6) 1.25 (0.86-1.82)
Electrical heating
No 1522 (91.9) 356 (93.4)
Yes 135 (8.1) 25 (6.6) 0.79 (0.51-1.23)
Type of dwelling
Single-family house 1459 (88.1) 317 (83.2)
Other dwelling type 198 (11.9) 64 (16.8) 1.49 (1.10-2.02)
Mean ± SD crowding 0.66±0.28 0.66±0.28 0.94 (0.63-1.42)
Mean ± SD % time 0.81±0.30 0.82±0.30 1.11 (0.76-1.61)
spent in location
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