Background Strategies to simplify HIV treatment are driven by concerns about the long-term toxicity of chronic combination antiretroviral therapy (ART), cost, and the risk of drug resistance over time due to non-adherence. Ritonavir-boosted protease inhibitors (PIs) can be an alternative.

Purpose To assess the effectiveness and safety of ritonavir-boosted PI monotherapy and whether the switching has been done in compliance with European AIDS Clinical Society guidelines.

Material and methods A large, retrospective observational, non-interventionist study was carried out including 91 patients on ritonavir-boosted PI monotherapy. Patients were followed since they started ART to December 2013 (the date at which all of the patients had been switched for at least 6 months). Data were collected and summarised in a table with the following characteristics: Date of HIV diagnose, PI/r monotherapy toxicity, Adherence and Date of starting with PI/r monotherapy, viral load at the moment of the simplification, viral load in December 2013.

Results 21 out of 91 (23%) patients had detectable HIV-RNA at the moment of the simplification thus they did not meet the guideline recommendations for switching. 15 out of 91 (16%) patients had a detectable viral load on December 2013 thus the switching had failed in them. Patients had fewer episodes of lipodystrophy, only 14 out of 91 (15%), and cardiovascular complications, only 4 out of 91 (4.35%). 84 out of 91 (92%) patients had more than 85% adherence to the treatment.

Conclusion The overall effectiveness of ritonavir-boosted protease inhibitor monotherapy is inferior to ART. However 84% of patients have no viral rebound with HIV-RNA levels above 50 copies/ml, which is why there may be a subset of patients with a history of prolonged viral suppression who may benefit from switching to ritonavir-boosted protease inhibitor (PI) monotherapy to reduce adverse reactions and costs, and achieve more adherence.

References and/or acknowledgements Hospital de La Princesa Team

No conflict of interest.