The number of
patients under follow-up in UK CHIC in the mid-point of each year from 2000 to 2007 was calculated. In order to be classed http://www.selleckchem.com/products/3-methyladenine.html as under follow-up in a given year, patients had to have at least one viral load and/or CD4 cell count measurement in the second half of the year (on or after 1 July) and the earliest date of the patient’s first viral load and CD4 cell count measurement was required to be before 1 July. The proportion of patients with a CD4 count <200 cells/μL and a viral load <50 copies/mL on 1 July of each year was also calculated (based on the measurement closest to 1 July). Patients were defined to be ART experienced in a given year if they had started ART before 1 July. Virological failure of a drug was defined as having occurred if a viral load >500 copies/mL was measured
in an individual, despite at least 6 months of continuous use of the drug. In order to be classed as having extensive triple class failure (ETCF), patients had to extensively fail all three of the original ART classes. Extensive failure of the nucleoside class was defined as virological failure of at least three drugs from the following: zidovudine, stavudine, lamivudine, emtricitabine, didanosine, find more tenofovir or abacavir. Extensive failure of the NNRTI class was defined as virological failure of efavirenz or nevirapine, and extensive failure of the PI class as virological failure of at least one ritonavir-boosted PI. Data from
SOPHID from 2000 onwards were used to determine trends in the total number of patients under care and the number on ART. As the breakdown of patients by risk group and ART status was somewhat different in CHIC compared with SOPHID, probably because the majority of the CHIC centres were in the London area [with a higher proportion of men who have sex with Liothyronine Sodium men (MSM) (58%vs. 42%, respectively, in 2007) and a higher proportion of patients on ART (76%vs. 71%, respectively, in 2007)], for all CHIC-based estimates risk group- and ART status-specific proportions were first obtained and then multiplied up to UK-wide estimates based on the breakdown of risk group and ART status from SOPHID. Death data calculations were based on the HPA’s national new HIV diagnoses and deaths database. The model of HIV infection and the effect of ART (HIV synthesis) that we used has been described in detail elsewhere [15,18]. In brief, it is a stochastic computer simulation model that generates data on the progression of HIV infection and the effect of ART on simulated patients. Variables updated every 3 months include calendar date, age, viral load, CD4 cell count, use of specific drugs, resistance and adherence.