title: Simple adherence assessments to predict virologic failure among HIV-infected adults with discordant immunologic and clinical responses to antiretroviral therapy.
abstract: We evaluated the association between two antiretroviral therapy (ART) adherence measurements--the medication possession ratio (MPR) and patient self-report--and detectable HIV viremia in the setting of rapid service scale-up in Lusaka, Zambia. Drug adherence and outcomes were assessed in a subset of patients suspected of treatment failure based on discordant clinical and immunologic responses to ART. A total of 913 patients were included in this analysis, with a median time of 744 days (Q1, Q3: 511, 919 days) from ART initiation to viral load (VL) measurement. On aggregate over the period of follow-up, 531 (58%) had optimal adherence (MPR > or =95%), 306 (34%) had suboptimal adherence (MPR 80-94%), and 76 (8%) had poor adherence (MPR <80%). Of the 913 patients, 238 (26%) had VL > or =400 copies/ml when tested. When compared to individuals with optimal adherence, there was increasing risk for virologic failure in those with suboptimal adherence [adjusted relative risk (ARR): 1.3; 95% confidence interval (CI): 1.0, 1.6] and those with poor adherence (ARR: 1.7; 95% CI: 1.3, 2.4) based on MPR. During the antiretroviral treatment course, 676 patients (74%) reported no missed doses. The proportion of patients with virologic failure did not differ significantly among those reporting any missed dose from those reporting perfect adherence (26% vs. 26%, p = 0.97). Among patients with suspected treatment failure, a lower MPR was associated with higher rates of detectable viremia. However, the suboptimal sensitivity and specificity of MPR limit its utility as a sole predictor of virologic failure.
authors: Centre for Infectious Disease Research in Zambia, Lusaka, Zambia.
authors: Jason D
authors: JD
authors: Goldman
authors: Ronald A
authors: RA
authors: Cantrell
authors: Lloyd B
authors: LB
authors: Mulenga
authors: Bushimbwa C
authors: BC
authors: Tambatamba
authors: Stewart E
authors: SE
authors: Reid
authors: Jens W
authors: JW
authors: Levy
authors: Mohammed
authors: M
authors: Limbada
authors: Angela
authors: A
authors: Taylor
authors: Michael S
authors: MS
authors: Saag
authors: Sten H
authors: SH
authors: Vermund
authors: Jeffrey S A
authors: JS
authors: Stringer
authors: Benjamin H
authors: BH
authors: Chi
mesh_terms: D000293:Adolescent; D044966:Anti-Retroviral Agents / Q000627:therapeutic use*; D005260:Female; D015658:HIV Infections / Q000097:blood / Q000188:drug therapy*; D006801:Humans; D008297:Male; D011446:Prospective Studies; D016312:Treatment Refusal; D014766:Viremia / Q000188:drug therapy; D015024:Zambia
chemical_list: D044966:Anti-Retroviral Agents