Table 4

Associations between SHS exposure (defined as measured plasma cotinine >0.05 ng/mL or above the limit of quantification if higher than 0.05 ng/mL) and asthma outcomes by study (as proxy for race/ethnicity) using multiple imputation data to account for missing NMR values

Asthma outcomesOR (95% CI)
Asthma exacerbations in the previous 12 months* 1.38 (0.95 to 2.01)1.27 (0.74 to 2.19)
Asthma control (binary outcome) 1.27 (0.84 to 1.91)2.16 (1.27 to 3.67)
 Not well controlled versus controlled1.21 (0.66 to 2.22)1.58 (0.87 to 2.91)
 Very poorly controlled versus controlled1.33 (0.80 to 2.22)2.77 (1.51 to 5.00)
  • *Asthma exacerbations assessed as a combined variable for any exacerbations (hospitalisations, ER visits, prescription of oral steroids) versus none.

  • †Asthma control assessed as binary outcome with a combined ‘not well controlled’ and ‘very poorly controlled’ category compared with controlled asthma.

  • ER, emergency room; GALA, Gene-environments and Admixture in Latino Americans; NMR, nicotine metabolite ratio; SAGE, Study of African Americans, Asthma, Genes and Environments; SHS, secondhand smoke.