after a mean follow-up of 55 weeks ( range , 19 to 107 ) , 33 of the subjects assigned to placebo had the acquired immunodeficiency syndrome ( aids ) , as compared with 11 of those assigned to receive 500 mg of zidovudine ( p = 0.002 ; relative risk , 2.8 ; 95 percent confidence interval , 1.4 to 5.6 ) and 14 of those assigned to receive 1500 mg of zidovudine ( p = 0.05 ; relative risk , 1.9 ; 95 percent confidence interval , 1.0 to 3.5 ) .
C0001175
acquired immunodeficiency syndrome
C0043474
zidovudine