These variables included follow-up CD4 cell count (Wald test P = 0.32), baseline CD4 cell count (Wald test P = 0.46), baseline WHO stage (Wald test P = 0.50), incident AIDS (Wald test P = 0.22), age (Wald test P = 0.09), gender (Wald test P = 0.63), and socio-economic status (Wald test P = 0.53). Here, CD4 is linked to AIDS.