Abstract

Effect of adherence on virological response to once-daily (qd) versus twice-daily (bid) darunavir/ritonavir (DRV/r) in treatment-experienced, HIV-1-infected patients with no DRV resistance-associated mutations (RAMs): ODIN 48-week data

C. Workman¹, P. Benson², J. Valdez Madruga³, A. Rieger⁴, T. Van de Casteele⁵, L. Lavreys⁵, S. Spinosa-Guzman<sup>5

1</sup>AIDS Research Initiative, Darlinghurst, Australia, ²Well Medical Center, Berkley, United States, ³Centro de Referência e Treinamento DST/AIDS, São Paulo, Brazil, ⁴Medical University of Vienna, Vienna, Austria, ⁵Tibotec BVBA, Mechelen, Belgium

Background: ODIN is a Phase IIIb, randomised, open-label study comparing DRV/r 800/100mg qd vs DRV/r 600/100mg bid at Week 48 in treatment-experienced, HIV-1-infected adult patients. Patients were included if they had no DRV RAMs at screening. In this analysis, adherence and its association with virological response to Week 48 were examined.
Methods: Mean adherence (Week 4-48) was assessed during the last 30 days prior to study visits over 48 weeks using (1) the Modified-Medication Adherence Self-Report Inventory (M-MASRI) questionnaire. Rates were transformed into binary variables of >95% (adherence) and ≤95% (suboptimal adherence). Adherence was also assessed by (2) DRV plasma concentrations (being above or below the detection limit of 10ng/mL), and (3) pill count (actual amount taken/amount to be taken).
Results: Across the three methods used, the percentage of patients who were adherent over the whole treatment period ranged from 57% to 83% (DRV/r qd) and 54% to 88% (DRV/r bid). Overall, adherent patients in both the DRV/r qd and bid groups achieved greater virological responses (HIV-1 RNA < 50 copies/mL intent-to-treat/time-to-loss of virological response) than suboptimally adherent patients (Table). In adherent patients, virological response to DRV/r qd was similar to that for DRV/r bid for each of the three adherence methods used.

	DRV/r 800/100mg qd		DRV/r 600/100mg bid		DRV/r qd - DRV/r bid
Parameter	N	Number of responders, n (%)	N	Number of responders, n (%)	Difference in response (%)	95% CI of difference in response (%)
Adherence measured by M-MASRI Adherent Suboptimally adherent	166 97	141 (84.9) 55 (56.7)	149 119	127 (85.2) 74 (62.2)	-0.3 -5.5	-8.2; 7.6 -18.7; 7.7
Adherence based on DRV plasma concentrations Adherent Suboptimally adherent	238 48	197 (82.8) 15 (31.3)	248 35	203 (81.9) 7 (20.0)	0.9 11.3	-5.9; 7.7 -8.1; 30.6
Adherence measured by pill count Adherent Suboptimally adherent	169 125	139 (82.2) 73 (58.4)	160 136	134 (83.8) 76 (55.9)	-1.5 2.5	-9.7; 6.7 -9.6; 14.6

[Virological response at W48 by adherence measure]

Conclusions: Regardless of the adherence methodology used, virological response was greater in adherent than suboptimally adherent patients in both DRV/r 800/100mg qd and 600/100mg bid arms. Adherent patients had comparable virological responses with DRV/r qd and DRV/r bid for each of the three adherence methods used.
Download the e-Poster