Background: High pill burden and side effects often impact on the long-term success of highly active antiretroviral therapy (HAART), which has led clinicians to search for more convenient regimens.
Patients and methods: A prospective, multicentre, open, comparative study in which HIV-1-infected patients on HAART and with plasma HIV-1 RNA <50 copies/ml for longer than 6 months were switched to tenofovir, didanosine and efavirenz (QD arm) or remained on the same treatment regimen (control arm). Patients with grade 4 toxicities or plasma HIV-1 RNA values repeatedly >1000 copies/ml discontinued the study.
Results: A total of 390 patients were included in the trial (309 in the QD arm and 81 in the control arm). The main baseline characteristics were well balanced between groups. In the QD arm, 41% of patients received high (standard) didanosine doses and 59% received reduced doses. At 12 months, plasma HIV-1 RNA <400 copies/ml was attained in 66% of QD patients and 73% of controls in the intent-to-treat (ITT) analysis (P=NS). However, the number of individuals with HIV-1 RNA <400 copies/ml in the QD arm was 56% versus 71% when comparing the use of high versus low didanosine doses (P=0.007). Treatment discontinuation occurred in 87 QD cases (28%) and 17 controls (21%). Twenty QD individuals (6.5%) and 2 controls (2.5%) discontinued because of virological failure (P=NS). The median CD4+ cell count change at 12 months was -26 and +27 cells/microl in QD patients and controls, respectively (P=0.001). In individuals who attained HIV-1 RNA <400 copies/ml, CD4+ cell changes were -25 and +15 cells/microl in QD patients and controls, respectively (P=0.001). Moreover, CD4+ cell declines in the QD arm were significantly greater in patients taking high versus low didanosine doses (-59 versus -15 cells/microl; P=0.04). The lipid profile improved significantly in the QD arm, particularly in patients who were on protease inhibitors prior to simplification.
Conclusions: Simplification to didanosine-tenofovir-efavirenz provides a virological suppression rate at 12 months similar to that seen in patients who do not change therapy, as long as low didanosine doses are administered. Decreases in CD4+ cell levels in patients in the QD arm (especially decreases seen with high didanosine doses) and dyslipidaemias along with less convenient pill burden and schedules in controls were the main long-term concerns for each option.