Differential impact of combined antiretroviral therapy on the survival of Italian patients with specific AIDS-defining illnesses

Background: A decrease in HIV-related mortality and morbidity has been observed since 1996 in most developed countries as a consequence of the extensive use of combined antiretroviral therapies. The purpose of this study was to investigate whether combined antiretroviral therapies had a differential impact on the survival of patients with different AIDS-defining illnesses (ADIs). Methods: In total, 35,318 persons representing all the adults with AIDS (PWAs) diagnosed in Italy from January 1, 1990 to August 31, 1998 were studied. Actuarial Life tables and the Kaplan-Meier method were used to estimate the cumulative probability of survival; the multivariate Cox proportional hazards model was used to estimate adjusted relative hazard of death (RH). Results: Among PWAs diagnosed after 1995, the proportion of survivors 24 months after diagnosis was more than doubled (66%) compared with that of PWAs diagnosed before the end of 1995 (31%). Significantly decreased RHs for some ADIs were observed as early as 1996 (i.e., esophageal candidiasis, Pneumocystis carinii pneumonia, brain toxoplasmosis, HIV-wasting syndrome, and pulmonary tuberculosis). In the last period (1997-1998), the decrease was marked and significant for almost all the ADIs, ranging from 55% to 80% compared with the RHs of the reference year (1995), Conversely, primary lymphoma of the brain and Burkitt's lymphoma showed a low and not statistically significant decrease; these were the ADIs with the worst outcome. Conclusions: After 1995, there was a rather uniform increase in the survival of PWAs diagnosed with most specific ADIs but not for patients affected by primary brain lymphoma and Burkitt's lymphoma. The determinants of this differential effect need to be investigated.