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Table 3 Odds ratios (ORs) and confidence intervals (CIs) for ischemic stroke risk in relation to residential modelled outdoor annual mean concentration of NOX.

From: Long-term exposure to air pollution and hospital admissions for ischemic stroke. A register-based case-control study using modelled NOxas exposure proxy

  First-phase analysis Second-phase analysis Two-phase analysis
    Partly adjusteda     Partly adjustedb   Fully adjustedc    
NOX
μg/m3
Cases
N(%)
Controls
N(%)
ORd CI Cases
N(%)
Controls
N(%)
ORe CI ORf CI ORg CIh
0–<10 1667 (34) 197371 (35) 1   1492 (34) 1784 (38) 1   1   1  
10–<20 1944 (40) 221981 (40) 1.03 0.97–1.10 1699 (39) 1923 (41) 1.07 0.91–1.25 1.00 0.85–1.2 0.97 0.90–1.05
20–<30 1065 (22) 110001 (20) 1.05 0.97–1.14 981 (22) 867 (18) 1.10 0.87–1.39 1.00 0.79–1.3 0.95 0.86–1.06
30–<60i 228 (5) 27559 (5) 0.91 0.79–1.05 203 (5) 142 (3) 1.28 0.90–1.82 1.20 0.85–1.76 0.87 0.73–1.03
  1. Partly adjusted first- and second-phase estimates, fully adjusted second-phase estimates and two-phase estimates: The two-phase estimates were calculated according to formula 1.
  2. a Adjusted for birth year category, sex, birth country and marital status.
  3. b Adjusted for a and for geographical area.
  4. c Adjusted for a, b and for smoking, diabetes and medication for hypertension.
  5. d The partly adjusted first-phase OR for an increase of 10 μg/m3 in NOx was OR1;Partl_adj= 0.99 (0.95–1.02), p for trend = 0.44.
  6. e The partly adjusted second-phase OR for an increase of 10 μg/m3 in NOx was OR2;Partly_adj= 1.09 (0.95–1.26), p for trend p = 0.21.
  7. f The fully adjusted second-phase OR for an increase of 10 μg/m3 in NOx was OR2;Fully_adjj= 1.07 (0.93–1.24), p = 0.33
  8. g The two-phase OR for an increase of 10 μg/m3 in NOx was OR1+2 = 0.97.
  9. h The widths of the two-phase CIs are likely slightly overestimated, due to dependence between the three combined estimates that we did not take into account.
  10. iMedian level of NOx in the category 30–<60 μg/m3 is 33.0 μg/m3 (10th–90th percentile: 30.4–40.5)