Background The use of generic alternatives to antiretroviral branded drugs may lead to substantial cost savings. However, this strategy could increase pill burden and may reduce adherence and potentially decrease virologic suppression rates.
Purpose To evaluate adherence, clinical and economic outcomes of the substitution of some of the drugs included in fixed dose antiretroviral coformulations by generic equivalents.
Material and methods Retrospective observational longitudinal study. All patients treated with coformulated emtricitabine-tenofovir-efavirenz with virologic supression were proposed to change their antiretroviral regimen (ART) to two pills of emtricitabine-tenofovir and generic efavirenz. Each patient was followed-up to assess the clinical response, and safety and adherence before and after the change. Data recorded were demographics (age, gender), viral load and drug adherence parameters from pharmacy records. Adherence was calculated as the medication possession ratio (days of medication supply compared with the number of days in a 6 month interval prior and after treatment change). The cost savings were calculated by comparing the cost of the 1 pill versus 2 pills over 1 year, using the official laboratory price. The Wilcoxon signed ranks test was used to compare adherence between periods.
Results 28 patients were included (mean age 47 years, 93% men). 22 patients accepted treatment change (79%). Mean follow-up was 6.5 months. Three patients returned to coformulated treatment due to insomnia and nightmares, and one patient changed to rilpivirine-tenofovir-efavirenz. Median adherence was 98.5% prior (interquartile range 94.2–101%) and 97.0% (87.5–100%) after treatment change (p = 0.435). All patients had adherence levels greater than 90% after the change. Viral load remained below detectable levels after the change for all patients. Regarding the financial impact of ART change, estimated cost saving could be 36.624€ per year in our centre.
Conclusion Rupture of the emtricitabine-tenofovir-efavirenz coformulation could lead to significant cost savings with no loss of virological efficacy.
No conflict of interest.
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