CD8A and pulmonary emphysema: The addition of markers previously associated with emphysema in our cohort, nadir CD4 cell count and sCD14, to the model did not attenuate the association between CD4/CD8 ratio and emphysema (OR 6.3, 95% CI 1.1–39 for CD4/CD8<0.4 compared to CD4/CD8>1.0).