All effect estimates were adjusted for age and cigarette smoking (ever versus never). The
results for models with age adjustment and for models with age and smoking adjustment
were nearly identical; consequently, we present the latter. We also performed analyses with
and without adjustment of cumulative exposure to endotoxin to address potential
confounding. Additional analyses with lagged exposures, by 10 and 20 years, were
conducted to take into account disease latency. The findings only changed minimally when
we adjusted for endotoxin or when exposures were lagged. Therefore, we only present
unlagged data without adjustment for endotoxin. All data analyses were performed with
SAS v 9.2.