Table 4 The interaction between serum cotinine levels and BMI on asthma in different ethnicity

Interaction¹

   Low-level serum cotinine and Group A

Ref

Ref

Ref

Ref

Ref

  Low-level serum cotinine and Group B

1.067 (0.799–1.424)

0.657

1.646 (1.05–2.580)

0.030

1.401 (1.035–1.897)

0.029

1.222 (0.893–1.673)

0.208

1.185 (0.656–2.141)

0.570

  Low-level serum cotinine and Group C

1.404 (1.063–1.856)

0.018

1.689 (1.123–2.540)

0.013

1.856 (1.290–2.669)

0.001

1.304 (0.974–1.746)

0.075

2.219 (1.464–3.363)

 < 0.001

  High-level serum cotinine and Group A

1.159 (0.746–1.800)

0.509

1.543 (0.872–2.730)

0.135

1.273 (0.873–1.858)

0.208

1.010 (0.784–1.301)

0.938

1.035 (0.611–1.755)

0.897

  High-level serum cotinine and Group B

1.154 (0.506–2.629)

0.731

2.437 (0.997–5.958)

0.051

1.333 (0.855–2.077)

0.203

1.087 (0.752–1.571)

0.654

2.403 (0.826–6.993)

0.107

  High -level serum cotinine and Group C

1.621 (0.953–2.756)

0.074

2.183 (1.110–4.294)

0.024

1.534 (0.899–2.616)

0.116

2.162 (1.66–2.815)

 < 0.001

2.373 (1.164–4.834)

0.018

Interaction

   Attributable proportion of interaction (95%CI)

0.114 (-0.500–0.729)

0.240 (-0.107–0.587)

0.055 (-0.185–0.295)

0.317 (0.097–0.538)

0.423 (0.085–0.760)

  Synergy index (95%CI)

1.205 (0.440–3.300)

1.874 (0.830–4.231)

1.207 (0.599–2.431)

1.901 (1.272–2.840)

2.495 (1.241–5.013)