The multivariable analysis that was adjusted for all the significant or clinically relevant variables, including CD4 lymphocyte count and AIDS stage, revealed that the only variables that maintained significance were age (hazard ratio, 1.07 for each year; 95% CI, 1.06–1.08; P < .001) and time in education >12 years (hazard ratio, 0.676; 95% CI, .45–.96; P = .031). Here, CD4 is linked to AIDS.