g. anti-cancer and other types of chemotherapy with bone marrow suppressive potential) may experience a temporary drop in CD4 cell count. If such a confirmatory CD4 cell count measurement is performed, both measurements should be below the threshold for the patient to fulfil the definition. The consensus definitions of persons presenting late for HIV care and presenting with advanced HIV diseases given in this paper will hopefully end the long-standing debate and the subsequent confusion regarding what is actually meant by a ‘late presenter’. Such

a central concept in public health is best served when a common definition exists. A similar definition has recently been proposed by a group of UK investigators [23], and hence this report SP600125 in vivo confirms that a consensus has been reached – in a parallel process – also on a European level. Europe-wide consensus on this issue is critical in formulating a continent-wide response to this public health crisis. Current guidance on the use of ART is of utmost importance in our consensus definition of a late presenter. Until 2007, ART was recommended to be deferred in asymptomatic persons until their CD4 count reached 200 cells/μL [24], but the guidelines then changed BTK signaling inhibitors when multiple studies demonstrated that persons living with HIV and with a current CD4 count in the range of 200–350 cells/μL

remained at significant risk of contracting opportunistic diseases [25, 26]. The findings from the SMART trial strongly supported this policy of initiating therapy in people with CD4 count <350 cells/μL. Therefore, initiation of ART when the CD4 count nears 350 cells/μL would reduce the incidence of such events. Serious non-AIDS events are observed at a higher incidence than AIDS events in persons living with CD4 counts >350 cells/μL,

particularly among those with an elevated underlying risk of such events [18, 27]. The December 2009 Department Microbiology inhibitor of Health and Human Services Antiretroviral (ARV) Guidelines for Adults and Adolescents recommend starting ARV therapy for patients with a CD4 count <500 cells/μL [28]. This controversial recommendation has not received general support across Europe at the present time. However, while our proposed threshold value of 350 cells/μL corresponds to the level at which ART is currently recommended in Europe, our proposed definition will not automatically change if future European guidelines change. Even if there is shown to be a relative benefit of starting ART at higher levels than at a CD4 count of 350 cells/μL (a point currently disputed), it is not evident that the definition of late presentation should change. This is because of the low risk of disease progression in people with CD4 counts >350 cells/μL and the fact that the time from infection to, for example, a CD4 count <500 cells/μL is relatively short, diluting the concept of ‘late presentation’ as a public health issue.