Postmarketing use of enfuvirtide in veterans: provider compliance with criteria for use, overall efficacy, and tolerability.
Most enfuvirtide outcomes data come from controlled trials of limited duration rather than from routine experience. Because of its uniqueness, the Veterans Health Administration (VHA) implemented specific enfuvirtide prescribing and follow-up criteria (criteria for use; CFU) and then assessed providers' compliance with these criteria and outcomes. To report routine medical care experience with the prescribing, efficacy, and tolerability of enfuvirtide in a nonselective group of treatment-experienced, older, HIV-infected veterans. Veterans receiving at least one outpatient prescription for enfuvirtide between April 2003 and July 2005 were identified from the VHA's HIV Clinical Case Registry (CCR:HIV). Targeted retrospective chart extraction was completed to address inclusion/exclusion criteria and to evaluate patients' continued use, adherence, and tolerance. CCR:HIV data were used for determination of demographics, prescription records, and laboratory results. The final cohort was used to assess providers' compliance with VHA's CFU for enfuvirtide. Of 275 evaluable subjects, between 52% and 93% who were prescribed enfuvirtide met each VHA CFU. Median change in CD4 cells and viral load from baseline to 6 months was +39 cells/mm(3) and -0.79 log(10) (p < 0.001) and at 2 years was +72 cells/mm(3) and -1.57 log(10) (p < 0.001); 41% and 55% of veterans achieved viral load less than 400 copies/mL at 6 months and 2 years, respectively. Seventy percent of veterans experienced injection site reactions (11% were treatment-limiting). New or worsening adverse effects occurred in 56% of veterans: 32% gastrointestinal, 19% musculoskeletal, and 10% respiratory. Seventy percent of veterans discontinued enfuvirtide within 2 years; the largest portion (12%) stopped treatment within the first month. Documented reasons for discontinuation included patient request (42%), suboptimal response/progression (24%), toxicity (18%), death (13%), and transfer of care outside of the VHA (3%). In this treatment-experienced veteran cohort, providers prescribed enfuvirtide in accordance with most CFU, and favorable treatment responses were sustained in patients able to remain on therapy. Challenges that providers and patients face include ongoing education and support for successful long-term use.