Limited or no therapeutic options (following multiple failing Mdm2 antagonist regimens, including the newer drugs with novel actions). Record in patient’s notes of resistance result at ART initiation (if available) and at first VL >400 copies/mL and/or before switch. Record in patient’s notes of adherence assessment and tolerability/toxicity to ART in patients experiencing virological failure or repeated viral blips. Number of patients experiencing virological failure on current ART regimen. Proportion of patients experiencing virological failure switched to a new suppressive regimen within 6 months. Proportion

of patients on ART with previously documented HIV drug resistance with VL <50 copies/mL. Record of patients with three-class virological failure with or without three-class resistance referred/discussed in multidisciplinary team with expert advice. In patients on ART: A single VL 50–400 copies/mL preceded and followed by an undetectable VL is usually not a cause for clinical concern (GPP). We recommend a single VL >400 copies/mL is investigated further, as it is indicative of virological failure (1C). We recommend in the context of repeated viral blips, resistance FK228 molecular weight testing is attempted (1D). Optimal HIV control is ordinarily

reflected by complete viral suppression with an undetectable VL. A virological blip is variably defined but for the purposes of these guidelines the definition that has been adopted is a detectable VL <400 copies/mL, which is preceded and followed by an undetectable result without any change of therapy. Blips are frequent and represent random variation around a mean undetectable VL [5-7]. Many patients have at least one at some time [8] when they are not predictive of virological failure or associated with emergent resistance in most studies [5, 9, 10]. VL assay variation and laboratory processing artefacts account for many blips (i.e. no ‘true’ increase in viral replication), which partly explains why blips do not appear to compromise long-term

outcomes [9, 11-13]. However, those with Farnesyltransferase sustained low-level increases in VL run a higher risk of virological failure. Most blips are low level [median magnitude 79 copies/mL in one study (range 51–201)] and short lived [median 2.5 days (range 2–11.5)] [7]. In a retrospective study, 28.6% of patients, experienced VL increases from 50 to 500 copies/mL over 8 years; 71% of these were blips [8]. Review and reiteration of the importance of full adherence, as well as looking for any tolerability/toxicity issues, DDIs/food interactions, and archived resistance should take place. However, blips do not appear to be related to intercurrent illness, vaccination, baseline CD4 cell count/VL, duration of preceding suppression or level of adherence [7, 14, 15].