CD4 and AIDS: Overall, compared with CD4/CD8 ratio > 0.4, CD4/CD8 ratio ≤ 0.4 doubled the risk of experiencing the composite endpoint (HR 2.00; 95%CI 1.63, 2.45), with a three-fold increased risk of an AIDS event (3.05; 95%CI 2.25, 4.12), and it was also associated with an increased risk of serious non-AIDS event (1.58; 95%CI 1.27, 1.97), and overall mortality (1.62; 95%CI 1.32, 1.98).