Background Current guidelines and trials (OK04, KalMo) support the Highly-Active AntiRetroviral Therapy (HAART) simplification, but long-term experience with this treatment is still limited.

Purpose To assess the Efficacy, Safety, Adherence and Costs related to HAART based on Ritonavir-boosted protease inhibitors (r/PI) versus the standard combinations based on reverse-transcriptase inhibitors (RTI) in long-term stable patients.

Materials and methods The virological and immunological laboratory tests, the adverse events (AE) profile and the Karnofsky score, along with the pharmacy withdrawal registry and the calculated monthly costs per patient were monitored at 3, 6, 9 and 12 months after simplification and compared with the average for the previous period. Databases: Andalusian digital or paper medical records and the outpatient database (Farmatools).

Results 13 patients were enrolled: 2 female versus 11 male, mean age: 44 years (29-68), mean HIV+ diagnosis and HAART: 61 months (3-88) and 53 months (4-93). Previous RTIs: emtricitabine/tenofovir, abacavir/lamivudine, abacavir/tenofovir and didanosine/lamivudine in 8, 3, 1 and 1 cases, respectively. HAART in the previous period included r/PIs (atazanavir/ritonavir, saquinavir/r and lopinavir/r) in 84% of the cases, though 92% were not maintained after simplification. Patients were switched to DRV/r and LPV/r in 11 and 2 cases, respectively. Comparative outcomes: sustained Viral Load <50 copies/mL (100% both groups) and CD4+ >350 cells/µL: 10 versus 11 patients (up to 76.9% of patients experienced increased lymphocyte levels after simplification). S (in the previous period): neurotoxicity (1 case), mild-to-moderate lipodystrophy (2) and cotrimoxazole-related skin disease (1). No noticeable AEs after simplification. Karnofsky: 100% (both groups). A: 5(±2) versus 2(±1) missed intakes. C: 859 versus 492€ (57.2% reduction).

Conclusions In our cohort, monotherapy was an alternative at least as effective as traditional combinations. In addition, it showed better adherence and tolerance, plus remarkable reduction in costs. Therefore this study encourages us to trust the results of large trials intended to demonstrate favourable profiles in long-lasting treatments for selected patients.