Definition and epidemiology of late presentation in Europe.

Accurate estimates of HIV prevalence in Europe are hampered by incomplete reporting of new HIV diagnoses. Defining the epidemiology of late presentation is even more challenging. In Europe, the most common definitions of late presentation are based on CD4(+) T-cell counts, but there is little consistency among definitions. Thus, estimates of the incidence of late presentation vary widely between studies and across Europe, making comparative analysis difficult. Late presentation has been observed to be common in all demographic groups, but certain factors indicate greater risk for late presentation, including intravenous drug use, older age, foreign birth and non-White ethnicity. Standardizing the definition of late presentation will facilitate understanding, clinical research and, ultimately, effective treatment of late-presenting patients.