TABLE 3.
ASSOCIATIONS BETWEEN TOBACCO SMOKE EXPOSURE AND ASTHMA CHARACTERISTICS IN THE OVERALL COHORT AND WITHIN PHENOTYPIC CLUSTERS
| Continuous Variables | All (n=154) | Cluster 1 (n=57) | Cluster 2 (n=33) | Cluster 3 (n=58) | ||||
|---|---|---|---|---|---|---|---|---|
| β*† (95% CI) | P Value† | β*† (95% CI) | P Value† | β*† (95% CI) | P Value† | β*† (95% CI) | P Value† | |
| Pre-bronchodilator FEV1, % predicted | 1.01 (−13.23 to 15.25) | 0.887 | 16.86 (−11.11 to 44.84) | 0.223 | −10.86 (−35.09 to 13.37) | 0.337 | −8.93 (−48.85 to 30.99) | 0.639 |
| FEV1 change with bronchodilator | 3.23 (−8.13 to 14.59) | 0.571 | 16.78 (−6.45 to 40.01) | 0.148 | 9.08 (−3.53 to 21.68) | 0.138 | −36.32 (−62.18 to −10.46) | 0.009 |
| Post-bronchodilator FEV1, % predicted‡ | 1.60 (−10.90 to 14.11) | 0.798 | 16.38 (−7.43 to 40.19) | 0.167 | −1.11 (−23.58 to 21.36) | 0.913 | −28.89 (−60.97 to 3.19) | 0.074 |
| Asthma control test™‡ | −0.72 (−3.92 to 2.49) | 0.656 | −5.17 (−8.42 to −1.93) | 0.003 | 2.23 (−3.17 to 7.62) | 0.375 | 4.96 (−5.38 to 15.29) | 0.321 |
| ITG -Composite Score§ | 0.06 (−0.06 to 0.17) | 0.308 | −0.08 (−0.25 to 0.09) | 0.325 | 0.18 (−0.04 to 0.40) | 0.092 | 0.21 (−0.14 to 0.55) | 0.220 |
| Nasal eosinophils‡§, % | −0.15 (−0.61 to 0.30) | 0.499 | −0.10 (−1.19 to 0.99) | 0.849 | −0.58 (−2.46 to 1.31) | 0.444 | 0.20 (−0.43 to 0.84) | 0.485 |
| Nasal neutrophils§, % | 0.44 (−0.04 to 0.93) | 0.073 | 0.73 (0.11 to 1.35) | 0.023 | 0.37 (−1.86 to 2.61) | 0.633 | −0.31 (−2.61 to 1.99) | 0.752 |
| Blood eosinophils§, % | −0.13 (−0.46 to 0.20) | 0.445 | 0.20 (−0.48 to 0.87) | 0.548 | −0.29 (−1.00 to 0.41) | 0.369 | −0.53 (−1.32 to 0.25) | 0.169 |
| Total serum IgE‡§, IU/mL | 0.05 (−0.51 to 0.60) | 0.867 | −0.05 (−1.08 to 0.99) | 0.926 | 0.93 (−0.47 to 2.33) | 0.168 | −0.35 (−1.61 to 0.91) | 0.558 |
| Categorical Variables | B*† (95% CI) | P Value† | B*† (95% CI) | P Value† | B*† (95% CI) | P Value† | B*† (95% CI) | P Value† |
| NAEPP severity classification | −0.64 (−2.03 to 0.75) | 0.365 | −1.77 (−4.31 to 0.77) | 0.172 | 1.88 (−1.93 to 5.68) | 0.334 | 0.53 (−3.21 to 4.28) | 0.780 |
| One or more positive skin prick tests, % | 1.63 (0.34 to 7.79) | 0.543 | 7.37 (0.25 to 216. 79) | 0.247 | 3.84 (0.14 to 104.56) | 0.425 | 0.11 (0.00 to 16.94) | 0.391 |
Abbreviations: ITG = Integrated Therapeutics Group’s Child Asthma Short Form; IgE = Immunoglobulin E; NAEPP = National Asthma Education and Prevention Program.
*
β or B coefficient is for each log10 increase in urine cotinine. Linear regression was used for all continuous variables, ordinal regression for NAEPP severity classification, and logistical regression for one or more positive skin prick tests.
†
Adjusted for age, gender, and BMI percentile. P Values <0.05 are listed in bold.
‡
Variables used to derive clusters.
§
Variables were log transformed to approximate a normal distribution.