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  53rd ICAAC Interscience Conference on
Antimicrobial Agents and Chemotherapy
September 10-13, 2013, Denver CO
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Adherence Better, In-Hospital Rate Lower With Single-Tablet ART in US Veterans
  53rd ICAAC, September 10-13, 2013, Denver
Mark Mascolini
Taking antiretroviral therapy (ART) consisting of a single once-daily tablet doubled chances of good adherence and cut chances of hospital admission 31% in a retrospective analysis of 15,600 US veterans taking antiretrovirals [1].
Single-tablet once-daily antiretroviral regimens have gained popularity because of their potency, convenience, and promotion of good adherence [2-4]. Some research suggests, though, that single-tablet regimens are not necessarily more durable than multitablet combinations [5].
To determine the impact of single-tablet ART among US veterans, researchers conducted this retrospective study of all veterans dispensed HIV medications between July 2006 and September 2011. They classified study participants into the single-tablet group if they took a single-tablet once-daily regimen at any time during the study period, and they classified participants into the multitablet group if they took a combination including more than two tablets daily and no single-tablet regimen at any time. They defined good adherence as a medication possession ratio of 95% or greater, which may not reflect how often a person actually takes doses as scheduled. Follow-up continued until treatment discontinuation, the end of the study period, the last recorded day of treatment, or death.
The analysis included 6191 veterans who took a single-tablet regimen and 9411 who took a multitablet regimen. Participants averaged 52 years in age, and average initial CD4 counts were similar in the single-tablet and multitablet groups (432.2 and 419.3, P = 0.287). Average Charlson Comorbidity index was similar in the single-tablet and multitablet group (1.5 and 1.7), as were proportions of veterans with mental health disorders (64.0% and 66.5%). A significantly lower proportion of veterans in the single-tablet group had an undetectable baseline viral load (42% versus 46%, P < 0.001), and a higher proportion in the single-tablet group was antiretroviral-naive when their study follow-up began (27.5% versus 12.7%).
During follow-up about 20% more veterans in the single-tablet group than in the multitablet group had at least 95% adherence (75% versus 55.7%, P < 0.001). The single-tablet group also had better adherence measured as at least an 80% medication possession ratio (90.0% versus 77.5%, P < 0.001). After statistical adjustment for baseline variables, veterans taking a single-tablet regimen had twice higher odds of at least 95% adherence (odds ratio [OR] 1.98, 95% confidence interval 1.81 to 2.37) and more than twice higher odds of at least 80% adherence (OR 2.36, 95% CI 1.92 to 2.43).
The hospital admission rate was significantly lower in the single-tablet group (26.8% versus 31.3%, P < 0.001). After statistical adjustment for baseline variables that may affect adherence and hospital admission, the single-tablet group was 31% less likely to get admitted to the hospital (hazard ratio 0.69, P < 0.001).
Among veterans admitted to the hospital at least once, those taking a single-tablet regimen averaged significantly fewer admissions than those taking a multitablet regimen (2.2 versus 2.7, P < 0.001). After statistical adjustment for baseline variables, veterans in the single-tablet group had 44% fewer hospital admissions than multitablet-treated veterans (incidence rate ratio 0.56, P < 0.001).
The investigators suggested that better adherence in the single-tablet group accounted for their lower hospital admission rate. Session cochair Joseph Eron observed that they could have verified that hypothesis if they repeated the multivariate analysis, added good adherence as a variable, and found that that adjustment abolished the association between single-tablet regimens and hospital admission.
Session cochair Pablo Tebas suggested that selection bias could influence the results. He reasoned that clinicians who suspect a patient will have poor adherence may be more likely to prescribe a protease inhibitor regimen (all of which are multitablet regimens) because failure of a PI regimen typically results in less resistance than failure of a nonnucleoside regimen, such as Atripla.
A published study of 1797 US patients taking a single-tablet regimen and 5584 taking a multitablet combination in 2005-2009 found better adherence and a 23% lower hospital admission rate in the single-tablet group [2].
1. Rao GA, Sutton SS, Hardin J, Bennett CL. Impact of highly active antiretroviral therapy regimen on adherence and risk of hospitalization in veterans with HIV/AIDS. 53rd ICAAC. September 10-13, 2013. Denver. Abstract H-1464.
2. Cohen CJ, Meyers JL, Davis KL. Association between daily antiretroviral pill burden and treatment adherence, hospitalisation risk, and other healthcare utilisation and costs in a US Medicaid population with HIV. BMJ Open. 2013;3:e003028. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3733306/
3. Cohen C, Elion R, Ruane P, et al. Randomized, phase 2 evaluation of two single-tablet regimens elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil fumarate versus efavirenz/emtricitabine/tenofovir disoproxil fumarate for the initial treatment of HIV infection. AIDS. 2011;25:F7-F12.
4. Bangsberg DR, Ragland K, Monk A, Deeks SG. A single tablet regimen is associated with higher adherence and viral suppression than multiple tablet regimens in HIV+ homeless and marginally housed people. AIDS. 2010;24:2835-2840.
5. Trottier B, Machouf N, Thomas R, et al. Single tablet regimens do not necessarily translate into more durable HIV treatments. 7th IAS Conference on HIV Pathogenesis, Treatment and Prevention. June 30-July 3, 2013. Kuala Lumpur. http://pag.ias2013.org/EPosterHandler.axd?aid=2764