Table 2

Association between an IQR of each air pollutant and asthma control

nPartly controlledUncontrolledOrdinalOrdinal (taking into account family dependence)Ordinal (taking into account family and city dependence)
OR* (95% CI)OR* (95% CI)OR† (95% CI)OR‡ (95% CI)OR§ (95% CI)
Crude
 NO24650.79 (0.59 to 1.07)0.88 (0.64 to 1.19)NANANA
 O3-an4811.45 (1.07 to 1.97)1.35 (0.98 to 1.86)NANANA
 O3-sum4811.60 (1.08 to 2.36)2.16 (1.41 to 3.30)1.78 (1.31 to 2.41)1.73 (1.29 to 2.31)1.73 (1.29 to 2.31)
 PM104811.18 (0.95 to 1.46)1.50 (1.19 to 1.89)1.34 (1.13 to 1.59)1.35 (1.13 to 1.61)1.26 (1.04 to 1.53)
Adjusted
 NO24540.84 (0.62 to 1.15)0.99 (0.71 to 1.40)NANANA
 O3-an4701.33 (0.96 to 1.84)1.19 (0.83 to 1.70)NANANA
 O3-sum4701.53 (1.01 to 2.33)2.14 (1.34 to 3.43)1.69 (1.22 to 2.34)1.69 (1.21 to 2.36)1.69 (1.22 to 2.34)
 PM104701.16 (0.92 to 1.46)1.60 (1.24 to 2.08)1.36 (1.13 to 1.64)1.40 (1.14 to 1.71)1.33 (1.06 to 1.67)

  • Each line represents a separate single-pollutant model. NA, not applicable, the ordinal model was not conducted for NO2 and O3-an due to the characteristics of the estimates derived from the multinomial logistic regression that do not suggest a gradual effect from partly controlled to uncontrolled asthma. Bold estimates make reference to estimates with a p<0.05.

  • ↵* ORs obtained from multinomial logistic regression comparing controlled versus partly controlled asthma and uncontrolled versus controlled asthma.

  • ↵† ORs obtained from ordinal logistic regression.

  • ↵‡ OR obtained from generalised linear models taking into account family dependence (level 2) and the ordinal model.

  • ↵§ OR obtained from generalised linear models taking into account family dependence (level 2) and city (level 3) and the ordinal model.

  • ↵ Adjusted for sex, age, body mass index, educational level, smoking and use of inhaled corticosteroids in the last year.