Table 1.
Associations of air pollutants with risk of incident IBD.
| IBD |
UC |
P | CD |
P | ||||
|---|---|---|---|---|---|---|---|---|
| Model 1 |
P | Model 2 |
P | Model 2 |
Model 2 |
|||
| HR (95% CI)a | HR (95% CI)b | HR (95% CI)b | HR (95% CI)b | |||||
| NOx | ||||||||
| Per IQR | 1.07 (1.03, 1.11) | 1.23E-04 | 1.04 (1.00, 1.08) | 4.23E-02 | 1.06 (1.02, 1.11) | 4.04E-03 | 0.97 (0.90, 1.05) | 4.34E-01 |
| Q1 | Ref | Ref | Ref | Ref | ||||
| Q2 | 1.02 (0.91, 1.14) | 7.84E-01 | 0.98 (0.87, 1.10) | 6.88E-01 | 1.02 (0.89, 1.17) | 7.63E-01 | 0.89 (0.72, 1.09) | 2.53E-01 |
| Q3 | 1.16 (1.04, 1.30) | 6.65E-03 | 1.10 (0.98, 1.23) | 9.80E-02 | 1.19 (1.04, 1.36) | 1.13E-02 | 0.91 (0.74, 1.12) | 3.65E-01 |
| Q4 | 1.04 (0.93, 1.16) | 4.83E-01 | 0.96 (0.86, 1.08) | 5.06E-01 | 1.07 (0.93, 1.22) | 3.53E-01 | 0.80 (0.64, 1.01) | 5.66E-02 |
| Q5 | 1.22 (1.09, 1.36) | 3.99E-04 | 1.13 (1.01, 1.26) | 3.87E-02 | 1.20 (1.05, 1.38) | 6.89E-03 | 0.96 (0.78, 1.18) | 6.95E-01 |
| P-trend | 7.40E-04 | 8.04E-02 | 7.18E-03 | 2.96E-01 | ||||
| NO2 | ||||||||
| Per IQR | 1.08 (1.04, 1.12) | 1.66E-04 | 1.06 (1.01, 1.10) | 9.78E-03 | 1.07 (1.02, 1.12) | 5.55E-03 | 1.02 (0.94, 1.10) | 6.78E-01 |
| Q1 | Ref | Ref | Ref | Ref | ||||
| Q2 | 1.09 (0.97, 1.21) | 1.49E-01 | 1.04 (0.92, 1.16) | 5.51E-01 | 1.06 (0.93, 1.22) | 3.91E-01 | 0.97 (0.79, 1.21) | 8.06E-01 |
| Q3 | 1.14 (1.02, 1.27) | 1.97E-02 | 1.08 (0.96, 1.20) | 2.12E-01 | 1.10 (0.96, 1.25) | 1.84E-01 | 1.03 (0.83, 1.27) | 8.19E-01 |
| Q4 | 1.18 (1.05, 1.31) | 3.97E-03 | 1.09 (0.97, 1.22) | 1.52E-01 | 1.13 (0.98, 1.29) | 8.24E-02 | 0.99 (0.80, 1.23) | 9.34E-01 |
| Q5 | 1.22 (1.09, 1.36) | 6.08E-04 | 1.14 (1.02, 1.28) | 2.55E-02 | 1.19 (1.03, 1.36) | 1.47E-02 | 1.03 (0.83, 1.29) | 7.65E-01 |
| P-trend | 2.14E-04 | 1.81E-02 | 1.02E-02 | 7.39E-01 | ||||
| PM10 | ||||||||
| Per IQR | 1.03 (0.99, 1.07) | 1.87E-01 | 1.01 (0.97, 1.06) | 5.93E-01 | 1.02 (0.97, 1.08) | 4.16E-01 | 0.99 (0.91, 1.07) | 7.56E-01 |
| Q1 | Ref | Ref | Ref | Ref | ||||
| Q2 | 1.10 (0.98, 1.22) | 9.44E-02 | 1.09 (0.97, 1.21) | 1.47E-01 | 1.14 (1.00, 1.29) | 5.30E-02 | 0.96 (0.77, 1.19) | 6.89E-01 |
| Q3 | 1.05 (0.94, 1.17) | 3.77E-01 | 1.04 (0.93, 1.16) | 5.41E-01 | 1.05 (0.92, 1.19) | 5.04E-01 | 1.01 (0.82, 1.24) | 9.37E-01 |
| Q4 | 0.94 (0.84, 1.05) | 2.87E-01 | 0.90 (0.80, 1.01) | 7.40E-02 | 0.88 (0.76, 1.00) | 5.85E-02 | 0.96 (0.78, 1.19) | 7.07E-01 |
| Q5 | 1.09 (0.97, 1.22) | 1.33E-01 | 1.06 (0.95, 1.20) | 2.86E-01 | 1.09 (0.95, 1.25) | 2.05E-01 | 1.00 (0.80, 1.24) | 9.75E-01 |
| P-trend | 9.16E-01 | 5.88E-01 | 5.33E-01 | 9.76E-01 | ||||
| PM2.5 | ||||||||
| Per IQR | 1.10 (1.05, 1.14) | 1.09E-05 | 1.06 (1.02, 1.11) | 7.92E-03 | 1.08 (1.02, 1.13) | 4.58E-03 | 1.02 (0.94, 1.11) | 6.44E-01 |
| Q1 | Ref | Ref | Ref | Ref | ||||
| Q2 | 1.02 (0.92, 1.15) | 6.78E-01 | 0.98 (0.88, 1.10) | 7.80E-01 | 1.02 (0.89, 1.17) | 8.13E-01 | 0.91 (0.73, 1.12) | 3.71E-01 |
| Q3 | 1.07 (0.96, 1.20) | 2.27E-01 | 1.01 (0.90, 1.13) | 8.52E-01 | 1.06 (0.92, 1.21) | 4.10E-01 | 0.90 (0.73, 1.12) | 3.37E-01 |
| Q4 | 1.18 (1.06, 1.31) | 3.06E-03 | 1.11 (0.99, 1.24) | 6.39E-02 | 1.19 (1.05, 1.36) | 8.72E-03 | 0.92 (0.75, 1.14) | 4.63E-01 |
| Q5 | 1.20 (1.07, 1.33) | 1.31E-03 | 1.10 (0.98, 1.23) | 9.94E-02 | 1.13 (0.99, 1.29) | 7.30E-02 | 1.03 (0.83, 1.27) | 8.05E-01 |
| P-trend | 6.09E-05 | 1.49E-02 | 7.52E-03 | 7.61E-01 | ||||
| Combined air pollution exposure score | ||||||||
| Per IQR | 1.09 (1.05, 1.14) | 1.75E-05 | 1.06 (1.01, 1.10) | 9.04E-03 | 1.08 (1.03, 1.13) | 2.58E-03 | 1.00 (0.92, 1.09) | 9.36E-01 |
| Q1 | Ref | Ref | Ref | Ref | ||||
| Q2 | 1.08 (0.97, 1.21) | 1.60E-01 | 1.03 (0.92, 1.15) | 6.51E-01 | 1.07 (0.93, 1.22) | 3.49E-01 | 0.93 (0.76, 1.16) | 5.33E-01 |
| Q3 | 1.14 (1.02, 1.28) | 1.90E-02 | 1.06 (0.95, 1.19) | 2.88E-01 | 1.12 (0.98, 1.28) | 9.74E-02 | 0.93 (0.76, 1.15) | 5.25E-01 |
| Q4 | 1.11 (0.99, 1.24) | 7.57E-02 | 1.02 (0.91, 1.14) | 7.49E-01 | 1.10 (0.96, 1.26) | 1.68E-01 | 0.84 (0.67, 1.04) | 1.08E-01 |
| Q5 | 1.29 (1.16, 1.44) | 4.98E-06 | 1.20 (1.07, 1.34) | 1.89E-03 | 1.26 (1.11, 1.45) | 6.46E-04 | 1.05 (0.85, 1.29) | 6.79E-01 |
| P-trend | 2.04E-05 | 6.39E-03 | 1.15E-03 | 9.36E-01 | ||||
IBD, inflammatory bowel disease; UC, ulcerative colitis; CD, Crohn's disease; CI, confidence interval; HR, hazard ratio; IQR, interquartile range; NO2, nitrogen dioxide; NOx, nitrogen oxides; PM, particulate matter.
P < 0.05 and >0.05/5 (0.01) was considered suggestive, P < 0.05/5 (0.01) after Bonferroni correction was considered significant and was bolded.
a
Model 1 was adjusted for age, sex, ethnicity.
b
Model 2 was adjusted for age, sex, ethnicity, assessment centers, household income, smoking status, education, BMI, physical activity, healthy diet, and alcohol consumption.