Table 4

Factors modifying FEV1 change (in mL) after work cessation based on a linear mixed effects model, with exposure modelled as cumulative occupational endotoxin exposure

FEV1, mL (95% CI)
Cessation-years11.8***(9.7 to 13.9)7.9***(5.7 to 10.1)
Cessation-years20.3***(0.1 to 0.4)0.3***(0.2 to 0.5)
Endotoxin×cessation-years−0.1*(−0.2 to −0.02)−0.1a(−0.1 to 0.03)
Current smoker×cessation-years1.1(−2.6 to 4.9)
Former smoker×cessation-years0.4(−4.4 to 5.2)
Male×cessation-years−5.7**(−9.1 to −2.3)−4.5**(−7.8 to −1.3)
  • Model adjusted for age, height, gender, exposure (cotton vs silk), smoking (never, current, former), cumulative pack-years and interaction terms between cessation-years and occupational exposure, cessation-years and smoking, and cessation-years and gender. Loss to follow-up accounted for by using inverse probability of censoring weights. Note: as the modelled outcome was FEV1 and not change in FEV1, the interaction terms with cessation-years represent the associations between occupational exposure, smoking, gender, and change in FEV1 after leaving work.

  • *p<0.05; **p<0.01; ***p<0.001

  • Quadratic interaction terms were significant only for the male×cessation-years2 term, with β=0.5 (0.2, 0.8), p=0.001 for all workers and β=0.4 (0.1, 0.7), p=0.02 for the analysis restricted to non-smokers.

  • †Cotton×cessation-years interaction p=0.08 in analysis restricted to non-smokers.

  • FEV1, forced expiratory volume in 1 s.