Background and importance HIV is currently one of the more expensive infectious diseases for the health system. Defining efficiency strategies is one way to save costs, in a system where resources are limited. A single tablet regimen (STR) is in some cases cost effective. Changing from one therapy to another does not compromise efficacy as it compares with equivalent alternatives.

Aim and objectives To describe an efficient strategy for switching to antiretroviral equivalent alternatives to save costs, and to perform a differences calculation simulation between them.

Material and methods We took into account the acquisition cost for each medication (according to our country regulations), and the dosage approved for them. We calculated the cost/treatment/year.

We analysed costs for antiretroviral treatments for patients and compared them with their equivalents. Avoided costs were calculated. We analysed all patients susceptible to a change to a more efficient equivalent therapeutic alternative. A simulation was carried out on the more and less efficient scenarios, and differences in costs were calculated.

Results A total of 136 patients were receiving different antiretroviral treatments in our hospital: 31 patients (22.8%) were direct candidates to change their treatment to another more efficient equivalent. Seventeen patients were receiving dolutegravir/abacavir/lamivudine in a single pill, which costs 117 455€/year. Changing to its equivalent in two pills (abacavir/lamivudine generic+dolutegravir brand) would mean a saving of 29 937€/year.

Eleven patients were receiving emtricitabine/tenofovir–disoproxil/rilpivirine in a single pill, which cost 79 466€/year. By replacing with its equivalent in two pills (emtricitabine/tenofovir–disoproxil generic+rilpivirine brand) would save 43 060€/year.

The opposite strategy was also analysed. Three patients were treated with dolutegravir+rilpivirine (both brands), which costs 22 016€/year. Recently, its therapeutic equivalent has been marketed in a single tablet, which using would mean 4735€/year saved. All of these interventions would mean a total saving of 77 732€/year.

Conclusion and relevance Correct positioning, evaluation and selection of high cost medicines improves efficiency in the infectious diseases area, where medicines have a high impact on the health system. In our specific case, the optimisation strategy was agreed and established together with the internal medicine service of our hospital, selecting the drugs without compromising efficacy or safety in patients.

References and/or acknowledgements No conflict of interest.