Table 4

Occupational asbestos exposure, smoking, genotype and IPF; interaction terms and stratified analysis (genotyped participants only, n=902)

Exposure*Adjusted OR† (95% CI; p value)
Interaction model (asbestos*smoking)
 Ever asbestos exposed0.6 (0.4 to 1.1; 0.08)
 Ever smoked0.9 (0.6 to 1.5; 0.68)
 Ever asbestos exposed and ever smoked interaction2.2 (1.2 to 4; 0.01)
Interaction model (asbestos*genotype)
 Ever asbestos exposed1.0 (0.7 to 1.5; 0.84)
 Genotype3.7 (2.4 to 5.8; 0.001)
 Ever asbestos exposed and genotype1.3 (0.8 to 2.3; 0.3)
Interaction model (smoking*genotype)
 Ever smoked1.29 (0.86 to 1.92; 0.22)
 Genotype3.95 (2.33 to 6.69; 0.001)
 Ever smoked and genotype1.15 (0.62 to 2.13; 0.65)
Stratified interaction model (asbestos*smoking)
 GT or TT
 Ever asbestos exposed0.4 (0.2 to 1; 0.06)
 Ever smoked0.6 (0.3 to 1.3; 0.2)
 Ever asbestos exposed and ever smoked interaction5.4 (1.8 to 15.6; 0.002)
  • *Ever asbestos exposed was defined as ever having had a high or medium asbestos exposure risk job, defined on the basis of occupational proportional mortality ratios for mesothelioma.16 Genotype of MUC5B rs35705950, T is the minor allele.

  • †Adjusted for age±smoking, smoking was not adjusted for when it was considered as an exposure. Centre was not adjusted for in this analysis because numbers were too small for one centre. Analysis limited to the 20 centres which did have sufficient numbers showed that adjusting for centre did not significantly change our results.

  • IPF, idiopathic pulmonary fibrosis.