Survival of patients with blood-borne AIDS in Italy.

Abstract

Background: AIDS represents an important public health problem in Italy. Long-term health care policy planning requires knowledge about the variability of the risk of mortality. The AIDS Surveillance Registry (RAIDS), maintained by the AIDS Operational Centre (COA) of the National Health Institute of Italy, provides valuable information to study the determinants of survival after diagnosis with AIDS. This study aimed to estimate the trends among people infected by the human immunodeficiency virus (HIV) through blood-related products.

Methods: Study subjects were 595 persons with AIDS whose sole ascertained risk factors were either blood transfusions or plasma-concentrate infusions, diagnosed from the beginning of the epidemic in 1985 through June 1995 and reported to RAIDS by the end of June 1996. The Kaplan-Meier technique was used to estimate the survival distribution; log-rank and Wilcoxon tests were both performed to assess the effects of demographic and clinical factors. Cox proportional hazards models were used to identify those factors independently and significantly associated with death: model building and fitting were performed in a stepwise fashion, by using the score and martingale residuals, based on a new class of graphical and numerical methods developed recently for checking the assumptions underlying the model.

Results and conclusions: In Italy the median survival time for AIDS patients infected by contaminated blood, was estimated to be 12.7 months. In univariate analyses it was found that women, younger patients (age < 35) and those diagnosed more recently with a higher value of CD4 cell counts (>37 cells m(-3)) have better survival. Patients diagnosed with AIDS-associated neurological disease (neuro-AIDS), or lymphoma, had a median survival significantly shorter. Patients diagnosed in the south of Italy tend to have a survival time shorter than patients diagnosed in the north. In a multivariate time-dependent regression analysis, only type of AIDS indicator disease, age and calendar time of diagnosis proved to be significant prognostic factors. It was not possible to estimate the effect of risk category (haemophiliacs versus transfused) due to the lack of proportionality in the estimated hazard. In conclusion, survival time is found to improve over time, indicating a likely positive effect of better care in treating HIV and AIDS patients.