AIDS across Europe, 1994-98: the EuroSIDA study

Background The clinical presentation of HIV-1 related diseases could have c hanged after the introduction of highly active antiretroviral treatment (HA ART). We aimed to assess changes over time in the incidence of ADIs overall and within CD4 lymphocyte count strata, the relationship with treatment an d degree of immunodeficiency at diagnosis of ADIs. Methods We did a prospective observational multicentre study of over 7300 p atients in 52 European HIV-1 outpatient clinics. Incidence rates per 100 pa tient-years of observation were calculated. Findings In total, we recorded 1667 new ADIs; the incidence of ADIs decline d from 30.7 per 100 patient-years of observation during 1994 (95% CI 28.0-3 3.4) to 2.5 per 100 patient-years of observation during 1998 (95% CI 2.0-3. 0, p<0.0001, test for trend). Median CD4 lymphocyte count at diagnosis of a new ADI increased from 28 cells/mu L to 125 cells/mu L between 1994 and 19 98 (p<0.0001), yet a steep decline in the rate of ADIs was seen after strat ification by latest CD4 lymphocyte count within each year (less than or equ al to 50, 51-200, and >200 cells/mu L). Patients on HAART had a lower rate of ADIs than patients not on this treatment within each CD4 lymphocyte coun t strata. The proportion of ADIs attributable to cytomegalovirus retinitis and Mycobacterium avium complex declined over time (p=0.0058 and 0.0022, re spectively), whereas the proportion of diagnoses attributable to non-Hodgki n lymphoma has increased (p<0.0001). In 1994, less than 4% of ADIs were non -Hodgkin lymphoma, in 1998 the proportion was almost 16%. This condition ha s become one of the most common ADIs in patients on HAART. Interpretation Our findings lend support to the idea that treatment regimen s can lower the incidence of ADIs. The immediate risk of an ADI for a given CD4 lymphocyte count has declined over time and is lower among patients on HAART. Long-term follow-up of patients on combination treatment is essenti al to monitor the incidence of new and emerging diagnoses.