A decrease in CD4 count achieved by six months (aHR: 2.4; 95% CI: 1.2–4.9) and small gains (0–49 cells/ml; aHR: 2.0; 95% CI: 1.2–3.4 and 50–99 cells/ml; aHR: 1.5; 95% CI: 0.9–2.2) were associated with 1.5- to 2.4-fold risk with respect to risk of progression to AIDS when compared to a change of ≥200 cells/ml. Here, CD4 is linked to AIDS.