001). The percentage of new prescriptions from physician extenders remained relatively constant across periods for all five medications. Seventy-to-eighty per cent of all new target medication prescriptions were from ID clinics,
10% from primary care clinics and 10% from other clinics (data not shown; P<0.001). From March 2003 until December 2007, 49% of all HIV-infected veterans who were prescribed antiretrovirals were in the Southern USA, 20% were in the West, 18% were in the Northeast, and 13% were in the Northcentral (Fig. 3). Significant shifts in prescribing by region over time occurred for Epigenetics inhibitor all target antiretrovirals. Lopinavir/ritonavir and atazanavir had earliest uptake in the West but by period 3 new prescribing had increased in
the South, closely matching prescribing of all antiretrovirals (P<0.001). Tipranavir had a similar pattern, with greatest early uptake in the West and much less uptake in the Northeast – a pattern that reversed over time (P=0.001). Darunavir had greatest initial uptake in the South but over time uptake increased in the Northeast and Northcentral regions and decreased in the South (P=0.03). Tipranavir and darunavir were FDA approved for use in treatment-experienced patients; hence, <2% of veterans prescribed these agents in any quarter were antiretroviral-naïve (data not shown). Of veterans who received atazanavir in the first two quarters post-approval, 2% C-X-C chemokine receptor type 7 (CXCR-7) were antiretroviral naïve compared with 9% of veterans who received it in later quarters after approval (P<0.001). Of providers prescribing any antiretrovirals within the VHA, the proportion that prescribed check details each target medication rose quickly over the first five-to-six
quarters and then plateaued (e.g. atazanavir) or declined (e.g. tipranavir) (Fig. 4). In the first quarter post-approval, <5% of all antiretroviral prescribers wrote prescriptions for the target medications. By the eighth quarter, however, nearly 30% of all providers prescribing any antiretrovirals within the VHA were prescribing atazanavir in a pattern matching that of lopinavir/ritonavir. For the other target medications, regardless of duration of follow-up, <10% of antiretroviral prescribers were prescribing these agents in any quarter. On average, in any quarter approximately 3750 VHA providers prescribed an antiretroviral. The peak number and percentage of providers prescribing atazanavir occurred in quarter 14 post-approval, with 1189 out of 3702 providers (32.1%) prescribing atazanavir. For darunavir, the number of providers was still increasing at the end of the study period, with 334 out of 3848 providers (8.7%) prescribing darunavir in quarter 6 (the last complete quarter for which data are available). The peak number of providers prescribing tipranavir occurred in the fifth quarter, with 171 out of 3654 providers (4.