Objectives: To investigate the occurrence of AIDS dementia complex (ADC) in Italy and its incidence over time, examining possible correlations between this condition and some demographic and immunological variables.
Design: Inception cohort. Data collected from the case notification forms of the Italian National AIDS Registry.
Subjects: 16813 consecutive AIDS cases reported to the National AIDS Registry from August 1, 1987 through October 31, 1993 were included.
Statistical methods: All data refer to the time of AIDS diagnosis as reported on the case notification forms. Main analyses of the monthly proportion of ADC cases were by multiple logistic regression.
Results: 1364 subjects (8.1%) were reported with a diagnosis of ADC as the first AIDS defining disease, either as the only manifestation or associated with other AIDS defining conditions. At the time of AIDS diagnosis, the observed ADC/AIDS proportion was significantly higher among intravenous drug users (IVDU), 9.1%, compared to heterosexuals, 6.3%, and homo-bisexual men, 5.2%. Simple logistic regression analysis showed a significant (p < 0.0001) quadratic trend in the monthly ADC/AIDS proportion, peaking in March 1990 and decreasing thereafter. Multiple logistic regression, adjusting for month of diagnosis, showed that IVDUs have consistently the highest risk and homo-bisexual men the lowest, although differences tended to decrease with increasing age. Older age, in fact, was highly associated with an increased risk, especially within the homo-bisexual and heterosexual transmission categories. CD4 + cells counts proved to have no significant effect on the risk of progressing to AIDS with ADC rather than with any other AIDS indicative disease.
Conclusions: ADC is a relatively frequent manifestation at diagnosis of AIDS among Italian patients, and particularly in IVDUs. Differences in its occurrence were found according to time of diagnosis, transmission category and age.