A comparison of zidovudine, didanosine, zalcitabine and no antiretroviral therapy in patients with advanced HIV disease.

Three nucleoside analogues, zidovudine (AZT), didanosine (ddI), and zalcitabine (ddC), are approved for use in the treatment of patients with HIV infection. This retrospective study compares the 3 drugs and examines the overall utility of antiretroviral therapy by way of comparisons to a no treatment (No Rx) group in patients with advanced HIV disease. Patients with advanced HIV disease were enrolled in didanosine (August 1989-December 1990) or zalcitabine (October 1990-February 1992) expanded access programmes; continued on zidovudine treatment despite fulfilling criteria for zidovudine failure or intolerance; or maintained on no antiretroviral treatment. Statistical analysis revealed that patients on nucleoside analogue therapy had fewer opportunistic infections (P = 0.001) than those who received no antiretroviral treatment. The Kaplan-Meier 12-month estimate of survival was significantly longer among patients who switched from zidovudine to zalcitabine but not among patients who switched to didanosine, when compared to the other 2 groups (P = 0.05).