Tenofovir diphosphate (TFV-DP) in dried blood spots was strongly associated with virologic suppression in people living with HIV and receiving TFV disoproxil fumarate-based therapies, according to data published in Clinical Infectious Diseases.
Dried blood spots were collected at 3 points over a period of 48 weeks from 532 persons living with HIV and receiving TFV disoproxil fumarate-based therapy. Among 347 people with virologic suppression at baseline, TFV-DP concentration was lower in black (1453) vs white patients (1793; P =.002) and vs Hispanic patients (1760; P =.025). TFV-DP concentration was alsolower in men, by 13%, compared to women, in non-boosted (1610 [1505, 1723]) vs boosted (1888; P =.002) antiretroviral regimens and also in non-nucleoside reverse transcriptase inhibitor-based (1563) vs boosted protease inhibitor-based (1890; P =.006) antiretroviral therapies and multiclass-based (1927; P =.022) antiretroviral regimens.
In addition, both viremic and virologically suppressed participants demonstrated higher TFV-DP concentrations in individuals who had a longer current duration of antiretroviral therapy. The adjusted odds ratio of virologic suppression after statistical adjustment for age, gender, race, body mass index, glomerular filtration rates, CD4+ T-cell count, antiretroviral drug class, and duration of therapy was 73.5 (95% CI, 25.7, 210.5; P <.0001) for a TFV-DP concentration ≥1850 fmol/punch compared with <350 fmol/punch.
Investigators noted that the study was limited as a result of its observational nature with adherence and virologic suppression data obtained via self-assessment and that the outcome-dependent sampling strategy may have strengthened the association. The study did benefit from a large sample size within a cohort reflective of clinical practice.
The investigators concluded that TFV-DP is strongly associated with viral suppression and is associated with certain patient characteristics; however, further research is required to better understand how these factors contribute to the pharmacology of TFV-DP and to assess their use as an adherence biomarker.
Castillo-Mancilla JR, Morrow M, Coyle RP, et al. Tenofovir Diphosphate in dried blood spots is strongly associated with viral suppression in individuals with HIV infection [published online August 23, 2018]. Clin Infect Dis. doi: 10.1093/cid/ciy708