Costs and adherence to antiretroviral treatment

Abstract

Objective

To develop a system of data management that allows us to estimate the comparative effectiveness of the various antiretroviral treatment (ART) regimens.

Method

Restrospective observational study in patients infected with HIV with stable ART. Adherence to treatment and unit cost for each patient's treatment was determined. The cost/ patient/day was calculated and, multiplying by an adherence factor (f_ADH), the (cost/patient/day)_ADH. The comparison of both allowed us to obtain the Δ_cost/patient, which estimates the additional costs caused by lack of adherence. The incremental cost-effectiveness (iCER), grouping the results by the various coformulated drugs (“combos”). A study of the budgetary impact of these combos was carried out.

Results

468 patients were evaluated (62% adherent). Average adherence was 88±18%. The average value of (cost/patient/day)_ADH was significantly higher than the cost/patient/day (27.3 ± 9.8 € compared to 24.3 ± 7.6 €, P<.001). Just as with the f_ADH, no differences were found in the Δ_cost/patient between the different ART combinations. The combo with the least deviation from the cost/patient/day due to lack of adherence was that composed of abacavir/zedovudine/lamivudine (ABC/AZT/3TC,Δ_cost/patient=8.72±14.18%), and that with the greatest deviation AZT/3TC (Δ_cost/patient=13.52 ± 17.68%). No significant differences were found in the iCER calcluated for any combo. The ART that included abacavir/lamivudine (ABC/3TC) obtained the least budgetary impact.

Conclusions

The greatest cost and percentage of adherent patients associated with the combos composed of Tenovovir/Emtricitabine(TDF/FTC) and ABC/3TC, and the least cost and effectiveness of those composed of AZT/3TC and ABC/AZT/3TC, does not allow us to identify any option as significantly dominant. The regimens with ABC/3TC were shown to be the most favourable from the combined point of view of cost and adherence.