Trends in age at AIDS diagnosis in Europe and the United States: Evidence of pronounced 'ageing' among injecting drug users

Objectives: To analyse trends in age at diagnosis for adult AIDS cases reported in Europe and the United States. Design: We used AIDS surveillance data for the seven European countries with the highest cumulative number of AIDS cases reported through June 1994 and for the United States through June 1993. Mean age at AIDS diagnosis over time was calculated by sex, transmission category and country. Linear regression yielded annual increase in age and permitted statistical evaluation of the trends observed. Annual AIDS incidence was calculated for homo-/bisexual men and injecting drug users (IDU) by 5-year age groups over time. Results: We found an overall increase in age at AIDS diagnosis among the main transmission categories in Europe and the United States. The epidemiologic profiles of the two regions were highly similar, despite the lower average age among IDU in Europe compared with the United States (30.6 versus 36.7 years) and lower annual increases in ape in the United States. In contrast to homo-/bisexual men, the increase in age at diagnosis is strikingly uniform and pronounced among IDU. Between 1986 and 1993, IDU in all countries exhibited at least a 6-month increase in age at diagnosis per annum. Although annual AIDS incidence remains consistent between various age groups of homo-bisexual men, IDU aged 30-49 years show continuing increase, whereas their younger counterparts show signs of stabilization or decrease. Conclusions: Despite different epidemic profiles and prevention policies, the age trends for the European countries examined and the United States were strikingly similar. The meaning of this general increase in age among the main transmission categories and the especially high increase among IDU may provide important insight into epidemic dynamics and intervention assessment.