Simple adherence assessments to predict virologic failure among HIV-infected adults with discordant immunologic and clinical responses to antiretroviral therapy.
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.
Goldman
Jason D
JD
Centre for Infectious Disease Research in Zambia, Lusaka, Zambia.
Cantrell
Ronald A
RA
Mulenga
Lloyd B
LB
Tambatamba
Bushimbwa C
BC
Reid
Stewart E
SE
Levy
Jens W
JW
Limbada
Mohammed
M
Taylor
Angela
A
Saag
Michael S
MS
Vermund
Sten H
SH
Stringer
Jeffrey S A
JS
Chi
Benjamin H
BH
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
D044966:Anti-Retroviral Agents