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Table 2 Prevalence and odds ratios (and 95% CI) of current wheezing by distance-based and emissions-based indicators of exposure before and after adjusting for person-based risk factors and co-morbidity as well as intra-school correlation in multivariable logistic models

From: Residential exposure to motor vehicle emissions and the risk of wheezing among 7-8 year-old schoolchildren: a city-wide cross-sectional study in Nicosia, Cyprus

  N Prevalence % Unadjusted (N = 1675) Adjusted1 (N = 1650) Adjusted2 (N = 1461)
A. Distance-based indicators      
1. By proximity > 300 m 622 9.0 1.00 1.00 1.00
  150-300 m 413 9.0 0.99 (0.62,1.59) 0.93 (0.57,1.54) 0.89 (0.52,1.50)
  100-150 m 195 8.6 0.97 (0.53,1.76) 0.89 (0.47,1.68) 1.01 (0.51,2.00)
  50-100 m 207 8.7 0.96 (0.55,1.67) 0.94 (0.54,1.63) 1.08 (0.61,89)
  < 50 m 238 11.7 1.35 (0.95,1.91) 1.27 (0.89,1.80) 1.30 (0.86,1.97)
2. Within 50 m of a main road No 1437 8.9 1.00 1.00 1.00
  Yes 238 11.7 1.36 (1.05,1.78) 1.32 (1.00,1.74) 1.33 (0.93,1.89)
3. Within 50 m of a road, stratified by levels of PM No 1437 8.9 1.00 1.00 1.00
  Yes, Low PM 148 10.1 1.15 (0.79,1.68) 1.10 (0.76,1.58) 1.10 (0.76,1.58)
  Yes, High PM 90 14.4 1.73 (1.06,2.81) 1.72 (1.04,2.84) 1.72 (0.92,3.20)
4. Within 50 m of a road, stratified by levels of NOx No 1437 8.9 1.00 1.00 1.00
  Yes, Low NOx 126 11.8 1.38 (0.94,2.03) 1.31 (0.90,1.91) 1.31 (0.88,1.93)
  Yes, High NOx 112 11.6 1.34 (0.82,2.20) 1.33 (0.81,2.21) 1.35 (0.75,2.43)
B. Distance-weighted emissions-indicators 3
1. PM at nearest street (kg/km per day) None 622 9.0 1.00 1.00 1.00
  Lowest (< 0.5) 748 8.8 0.98 (0.68,1.41) 0.92 (0.63,1.35) 0.97 (0.67,1.41)
  Medium (0.5-1) 215 9.7 1.09 (0.72,1.66) 1.02 (0.68,1.54) 1.05 (0.67,1.65)
  Highest (> 1) 90 14.4 1.71 (1.00,2.90) 1.65 (0.96,2.81) 1.67 (0.82,3.38)
  P-value for trend   0.12 0.22 0.26
2. PM at street with highest levels (kg/km per day) None 622 9.0 1.00 1.00 1.00
  Lowest (< 0.5) 757 8.7 0.97 (0.67,1.39) 0.91 (0.62,1.33) 0.95 (0.65,1.37)
  Medium (0.5-1) 202 10.3 1.17 (0.77,1.78) 1.09 (0.72,1.65) 1.13 (0.72,1.75)
  Highest (> 1) 94 13.8 1.62 (0.96,2.75) 1.57 (0.92,2.67) 1.65 (0.84,3.25)
  P-value for trend   0.11 0.20 0.20
3. NOx at nearest street (kg/km per day) None 622 9.0 1.00 1.00 1.00
  Lowest (< 10) 725 8.5 0.95 (0.64,1.39) 0.89 (0.59,1.33) 0.92 (0.62,1.37)
  Medium (10-20) 230 11.6 1.34 (0.88,2.06) 1.27 (0.83,1.95) 1.35 (0.85,2.14)
  Highest (> 20) 98 11.2 1.28 (0.74,2.20) 1.23 (0.71,2.14) 1.19 (0.58,2.47)
  P-value for trend   0.19 0.31 0.31
4. NOx at street with highest levels (kg/km per day) None 622 9.0 1.00 1.00 1.00
  Lowest (< 10) 813 9.7 1.09 (0.78,1.53) 1.02 (0.72,1.46) 1.08 (0.76,1.53)
  Medium (10-20) 135 6.6 0.72 (0.36,1.47) 0.70 (0.35,1.41) 0.71 (0.32,1.59)
  Highest (> 20) 105 11.4 1.30 (0.76,2.25) 1.23 (0.70,2.18) 1.21 (0.61,2.42)
  P-value for trend   0.75 0.94 0.91
  1. 1Adjusted for gender and smoking during pregnancy, 2Also adjusting for co-morbidity (i.e. eczema, hay fever and family history of atopy) and all other risk factors except birthweight, 3 Cut-off points for levels of exposure were defined based on the 50% and 75% (i.e. highest quartile) of the distribution of non-zero values.