Effectiveness, Safety, and Costs of Dolutegravir/Abacavir/Lamivudine Single-Tablet Regimen in a Real-Life Cohort of HIV-1 Adult Infected Patients.

Background: Real-life data on single-tablet regimen (STR) dolutegravir/abacavir/lamivudine (DTG/ABC/3TC) is scarce, and concerns about DTG neuropsychiatric adverse events (NP-AEs) have recently arisen. Objective: To explore the effectiveness and safety, in particular NP-AEs, of DTG/ABC/3TC in a cohort of HIV-1 adult infected patients. Pill burden, adherence to this STR, and the impact of switching on costs were also evaluated. Methods: This was an observational, retrospective study. The study population included antiretroviral therapy (ART)-naive and treatment-experienced (TE) patients who started DTG/ABC/3TC between February 1, 2016, and October 31, 2016. Effectiveness and safety were analyzed at week 48 (W48) by intention-to-treat analysis. The Cox regression model was used to investigate predictors of DTG/ABC/3TC discontinuation. Results: A total of 253 patients were included (44 ART naïve, 209 TE). At W48, the proportion of patients with virological suppression was 72.7% (95% CI = 58.4-87.0) in ART-naive patients, 85.6% (95% CI = 80.3-90.9) in previously suppressed TE patients, and 86.4% (95% CI = 65.1-97.1) in previously not suppressed TE patients. The rate of protocol-defined virological failure was 4.3%. The incidence of AEs was higher in the subgroup of ART-naive patients (56.1% vs 39.0%), with a rate of interruptions for this reason of 13.6% and 7.6%, respectively. The incidence of NP-AEs was 20.6%, with 3.9% of patients requiring discontinuation. Patients who had switched from a raltegravir-containing regimen discontinued DTG/ABC/3TC because of AEs more frequently (relative risk = 2.83; 95% CI = 1.04-7.72; P = 0.041) in the multivariate analysis. After switching to DTG/ABC/3TC, the median pill burden was reduced from 3 to 1 and the proportion of patients with an adherence <90%, from 20.1% to 12.0%. The annual per-patient ART costs increased by €48 (0.6% increase). Conclusion and Relevance: DTG/ABC/3TC is an effective strategy as first-line and switching ART. Our data suggest a worse tolerance in ART-naive patients, although the rate of discontinuation resulting from NP-AEs was relatively low. In the short-term, the adherence was slightly improved without significant changes in costs.

De-simplifying single-tablet antiretroviral treatments: uptake, risks and cost savings.

OBJECTIVES: As more HIV-positive individuals receive antiretroviral therapy (ART), payers are seeking options for covering these increased and sustained drug costs. Strategic use of available generic antiretroviral (ARV) formulations may be feasible. De-simplifying a single-tablet co-formulation (STF) into two or more tablets using both brand and generic drugs has been proposed. We determine if voluntary de-simplification of one STF could be utilized as a cost-saving strategy. We report on the challenges, uptake, outcomes and cost savings of this initiative. METHODS: Patients stable on the most commonly used STF (Triumeq® ) were offered the option of remaining on Triumeq® or switching to generic abacavir/lamivudine and Tivicay® between 1 January 2015 and 1 January 2018; those starting ART consisting of abacavir/lamivudine/doulutegravir in the same period were offered the option of starting Triumeq® or generic abacavir/laminvudine and Tivicay® . No incentives were provided. We examined the acceptance/decline rates, patient satisfaction, health care outcomes and annual cost savings. RESULTS: Of 626 patients receiving Triumeq® , 321 were approached; 177 (55.1%) agreed to de-simplify. Of patients initiating ART, 62.7% chose the generic co-formulation. Patients switching to or starting on the generic co-formulation were more likely to be male, > 45 years old, Caucasian, men who have sex with men (MSM) and more HIV-experienced, and to have more comorbidities (all P < 0.05). Preference for STF was cited for declining de-simplification. No concern about generic ARVs was expressed. The rate of viral load > 500 HIV-1 RNA copies/mL after baseline was 2.7% in switched patients compared with 7.0% in those declining to switch. No de novo resistance occurred. A saving of Cdn$1 319 686 was achieved in the first year. CONCLUSIONS: Reliance on altruism, while respecting patient autonomy, achieved de-simplification in > 50% of patients approached, and generated immediate cost savings with no increased risk of adverse events, viral breakthrough or resistance.

Patient perspectives on de-simplifying their single-tablet co-formulated antiretroviral therapy for societal cost savings.

OBJECTIVES: The incremental costs of expanding antiretroviral (ARV) drug treatment to all HIV-infected patients are substantial, so cost-saving initiatives are important. Our objectives were to determine the acceptability and financial impact of de-simplifying (i.e. switching) more expensive single-tablet formulations (STFs) to less expensive generic-based multi-tablet components. We determined physician and patient perceptions and acceptance of STF de-simplification within the context of a publicly funded ARV budget. METHODS: Programme costs were calculated for patients on ARVs followed at the Southern Alberta Clinic, Canada during 2016 (Cdn$). We focused on patients receiving Triumeq® and determined the savings if patients de-simplified to eligible generic co-formulations. We surveyed all prescribing physicians and a convenience sample of patients taking Triumeq® to see if, for budgetary purposes, they felt that de-simplification would be acceptable. RESULTS: Of 1780 patients receiving ARVs, 62% (n = 1038) were on STF; 58% (n = 607) of patients on STF were on Triumeq®. The total annual cost of ARVs was $26 222 760. The cost for Triumeq® was $8 292 600. If every patient on Triumeq® switched to generic abacavir/lamivudine and Tivicay® (dolutegravir), total costs would decrease by $4 325 040. All physicians (n = 13) felt that de-simplifying could be safely achieved. Forty-eight per cent of 221 patients surveyed were agreeable to de-simplifying for altruistic reasons, 27% said no, and 25% said maybe. CONCLUSIONS: De-simplifying Triumeq® generates large cost savings. Additional savings could be achieved by de-simplifying other STFs. Both physicians and patients agreed that selective de-simplification was acceptable; however, it may not be acceptable to every patient. Monitoring the medical and cost impacts of de-simplification strategies seems warranted.

Cost-effectiveness of dolutegravir/abacavir/lamivudine in HIV-1 treatment-Naive (TN) patients in France.

BACKGROUND: To evaluate the cost-effectiveness of an integrase inhibitor (INI), dolutegravir (DTG), in combination with abacavir (ABC)/lamivudine (3TC) in France, in treatment-naive (TN) HIV adult patients. METHODS: The ARAMIS microsimulation Markov model, evaluates costs and effects of DTG vs. first-line ARVs options including INIs (raltegravir, elvitegravir/c), protease inhibitors (PIs) (darunavir/r, atazanavir/r, lopinavir/r), non-nucleoside reverse transcriptase inhibitors (efavirenz and rilpivirine). Efficacy and safety data were derived from phase III studies and network meta-analysis. Treatment algorithms were based on French guidelines and experts opinion. Costs included routine HIV and opportunistic infection care, and death. RESULTS: The model showed the fixed-dose combination DTG/ABC/3TC was more effective than all other recommended regimens: patients stayed longer on first-line, and lived longer and healthier. With the exception of EFV, DTG/ABC/3TC was more efficacious and less costly compared to all strategies. The cost per QALY gained (ICER) for DTG compared to EFV was €6,939. DTG/ABC/3TC was more efficacious and less costly compared to INIs and PIs in all deterministic sensitivity analyses. CONCLUSION: DTG/ABC/3TC was cost-effective in the management of HIV TN patients in France. These results are mainly explained by its lower price compared to other INIs and PIs, DTG's superior efficacy and high barrier to resistance.

[CLINICAL AND PHARMACOECONOMIC RESULTS OF THE USAGE OF VARIOUS HIV REVERSE TRANSCRIPTASE INHIBITORS IN THE SCHEMES OF ANTIRETROVIRAL THERAPY OF PATIENT RECEIVING THERAPY FOR THE CHRONIC HEPATITIS C VIRUS].

Efficacy, safety, and economical aspects of treatment with abacavir, zidovudine, stavudine, and phosphazide in the schemes of antiretroviral therapy of the HIV-infected patients receiving therapy for hepatitis C virus were tested. Clinical, immunological, and virologic efficacy of treatment and dynamics of hemoglobin, thrombocytes, and alanine aminotransferase as markers of common adverse events recorded at the start of the antiviral therapy of chronic hepatitis C and after 4, 8, 12, 24, 48 weeks of the treatment were evaluated. The usage of these drugs in the schemes of antiretroviral therapy exhibited efficacy, high tolerability and safety for all HIV reverse transcriptase inhibitors.

Antiretroviral therapy management and rationalisation of available resources.

The treatment of HIV disease has led to a new division of management costs by shifting most of the necessary resources from inpatient treatment to outpatient management. Among the initiatives aimed at rationalising the resources available, we compared efficacy, tolerability and pharmacoeconomic impact of different regimes of antiretroviral therapy (ART). The survey covered the first 50 patients, clinically stable and with good viro-immunological response, who switched in June 2012 from an ART based on the triple combination of tenofovir (TDF), emtricitabine (FTC) and a protease inhibitor boosted with ritonavir (PI/r) or a non-nucleoside reverse transcriptase inhibitor (NNRTI), to a treatment based on abacavir (ABC), lamivudine (3TC) and a PI/r or NNRTI. Of the 50 patients who operated the switch, 39 replaced a PI with nevirapine (NVP), for which the largest group of patients was treated with ABC + 3TC + NVP. On 31 May 2015, all patients completed the observation period of 96 weeks, with a mean observation period of 132 weeks and clinical-laboratory checks every four months. Laboratory analysis revealed an optimal maintenance of viral suppression and absolute and relative number of CD4 + lymphocytes and improving trend of creatinine, proteinuria, serum phosphate and bone alkaline phosphatase. There was a variable effect on lipids, with a drop in triglycerides associated with a modest increase in total cholesterol. Much of the HIV-positive population reporting to our hospitals (>50%) comprises individuals who have for years been in stable viraemic suppression, making a satisfactory immune recovery while in good overall clinical condition. This type of patient was the target of the present survey. At the end of 96 weeks of observation the new regimes were well tolerated and did not lead to viro-immunological or clinical deterioration. Pharmacoeconomic analysis showed better containment of the overall costs. No patient needed to be hospitalised during the observation period.

Cost-effectiveness of DTG + ABC/3TC versus EFV/TDF/FTC for first-line treatment of HIV-1 in the United States.

OBJECTIVE: Data from the SINGLE trial demonstrated that 88% of treatment-naïve HIV-1 patients treated with dolutegravir and abacavir/lamivudine (DTG + ABC/3TC) achieved viral suppression at 48 weeks compared with 81% of patients treated with efavirenz/tenofovir disoproxil fumarate/emtricitabine (EFV/TDF/FTC). It is unclear how this difference in short-term efficacy impacts long-term cost-effectiveness of these regimens. This study sought to evaluate long-term cost-effectiveness of DTG + ABC/3TC vs EFV/TDF/FTC from a US payer perspective. METHODS: This study is an individual discrete-event simulation which tracked the disease status and treatment pathway of HIV-1 patients. The model simulated treatment over a lifetime horizon by tracking change in patients' CD4 count, clinical events occurrence (opportunistic infections, cancer, and cardiovascular events), treatment switch, and death. The model included up to four lines of treatment. Baseline patient characteristics, efficacy, and safety of DTG + ABC/3TC and EFV/TDF/FTC were informed by data from the SINGLE trial. The efficacy of subsequent treatment lines, clinical event risks, mortality, cost, and utility inputs were based on literature and expert opinion. Outcomes were lifetime discounted medical costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratio (ICER). RESULTS: Compared with EFV/TDF/FTC, DTG + ABC/3TC increased lifetime costs by $19,153 and per person survival by 0.12 QALYs, resulting in an ICER of $158,890/QALY. ICERs comparing DTG + ABC/3TC to EFV/TDF/FTC remained above the traditional, US willingness-to-pay threshold of $50,000/QALY gained in all scenarios, and above $100,000 or $150,000/QALY gained in most scenarios. LIMITATIONS: Due to data limitations, the treatment patterns, CD4 count during viral rebound and treatment switch, viral rebound after trial end, and long-term adverse event-related treatment discontinuation were based on assumptions, presented to and approved by clinical experts. CONCLUSIONS: Compared with EFV/TDF/FTC, DTG + ABC/3TC resulted in higher cost and only slightly increased QALYs over a lifetime, with an ICER that exceeded the standard cost-effectiveness threshold. This indicates that the incremental benefit in effectiveness associated with DTG + ABC/3TC may not be worth the incremental increase in costs.

Reducing hypersensitivity reactions with HLA-B*5701 genotyping before abacavir prescription: clinically useful but is it cost-effective in Singapore?

AIM: Abacavir (ABC) is one of the more affordable antiretroviral drugs used for controlling HIV. Although with similar efficacy to current first-line drugs, its limited usage in Singapore can be attributed to its possible side effect of adverse hypersensitivity reactions (HSRs). HLA-B*5701 genotyping is a clinically relevant procedure for avoiding abacavir-induced HSRs. As patients who do not carry the risk allele are unlikely to develop HSRs, a simple rule can be developed to allow abacavir prescription for patients who are B*5701 negative. Here, we carry out a cost-effectiveness analysis of HLA-B*5701 genotyping before abacavir prescription in the context of the Singapore healthcare system, which caters predominantly to Han Chinese, Southeast-asian Malays, and South-asian Indians. In addition, we aim to identify the most cost-effective treatment regimen for HIV patients. METHODS: A decision tree model was developed in TreeAge. The model considers medical treatment and genotyping costs, genotyping test characteristics, the prevalence of the risk allele, reduction in the quality of life, and increased expenditure due to side effects and other factors, evaluating independently over early-stage and late-stage HIV patients segmented by drug contraindications. RESULTS: The study indicates that genotyping is not cost-effective for any ethnicity irrespective of the disease stage, except for Indian patients with early-stage HIV who are contraindicated to tenofovir. CONCLUSION: Abacavir (as first-line) without genotyping is the cheapest and most cost-effective treatment for all ethnicities except for early-stage Indian HIV patients contraindicated to tenofovir. The HLA-B*5701 frequency, the mortality rate from abacavir-induced HSRs, and genotyping costs are among the major factors influencing the cost-effectiveness.

Cost-effectiveness of nucleoside reverse transcriptase inhibitor pairs in efavirenz-based regimens for treatment-naïve adults with HIV infection in the United States.

OBJECTIVE: To estimate the cost-effectiveness of once-daily tenofovir/emtricitabine compared with twice-daily zidovudine/lamivudine and once-daily abacavir/lamivudine in treatment-naïve adults with HIV-1 infection in the United States. METHODS: A Markov model with four therapy lines and six health states based on CD4(+) cell-count ranges was developed to estimate lifetime costs and health outcomes. Efficacy data (virologic response and CD4(+) cell-count changes) for first-line therapy were from 144-week results of Study 934 comparing tenofovir/emtricitabine with zidovudine/lamivudine and 48-week results of Study CNA30024 comparing abacavir/lamivudine with zidovudine/lamivudine, all in combination with efavirenz. Data from Study CNA30024 for abacavir/lamivudine were adjusted to allow for an indirect comparison with tenofovir/emtricitabine. Subsequent therapy lines were based on likely baskets of antiretroviral therapy recommended by US treatment guidelines. Utility values, mortality rates, and costs (2009 US dollars) were obtained from published sources. Base-case results were tested in sensitivity and variability analyses. RESULTS: Average discounted results showed that individuals using tenofovir/emtricitabine were predicted to remain on first-line therapy for 7.7 years, accrue lifetime costs of $747,327, and experience 15.75 quality-adjusted life-years (QALYs), compared with 6.0 years, $777,090, and 15.68 QALYs for individuals using abacavir/lamivudine and 5.8 years, $778,287, and 15.44 QALYs for individuals using zidovudine/lamivudine. Tenofovir/emtricitabine was cost-effective compared with the other two first-line regimens in more than 75% of all probabilistic sensitivity analysis simulation runs for every willingness-to-pay threshold between $0 and $250,000 per QALY gained. Results were robust in variability and one-way sensitivity analyses. CONCLUSIONS: Tenofovir/emtricitabine was predicted to be more effective and cost-saving compared with abacavir/lamivudine and zidovudine/lamivudine in treatment-naïve adults with HIV-1 infection in the United States.

Optimizing antiretroviral product selection: a sample approach to improving patient outcomes, saving money, and scaling-up health services in developing countries.

Over the last decade, increased funding to support HIV treatment programs has enabled millions of new patients in developing countries to access the medications they need. Today, although demand for antiretrovirals continues to grow, the financial crisis has severely constrained funding leaving countries with difficult choices on program prioritization. Product optimization is one solution countries can pursue to continue to improve patient care while also uncovering savings that can be used for further scale up or other health system needs. Program managers can make procurement decisions that actually reduce program costs by considering additional factors beyond World Health Organization guidelines when making procurement decisions. These include in-country product availability, convenience, price, and logistics such as supply chain implications and laboratory testing requirements. Three immediate product selection opportunities in the HIV space include using boosted atazanavir in place of lopinovir for second-line therapy, lamivudine instead of emtricitabine in both first-line and second-line therapy, and tenofovir + lamivudine over abacavir + didanosine in second-line therapy. If these 3 opportunities were broadly implemented in sub-Saharan Africa and India today, approximately $300 million of savings would be realized over the next 5 years, enabling hundreds of thousands of additional patients to be treated. Although the discussion herein is specific to antriretrovirals, the principles of product selection are generalizable to diseases with multiple treatment options and fungible commodity procurement. Identifying and implementing approaches to overcome health system inefficiencies will help sustain and may expand quality care in resource-limited settings.

Economic efficiency of genetic screening to inform the use of abacavir sulfate in the treatment of HIV.

BACKGROUND: Abacavir sulfate (abacavir) is associated with a hypersensitivity reaction (HSR) that affects 5-8% of patients. While serious complications are rare, failure to identify it, or abacavir re-challenge following HSR, can be fatal. Genetic screening for HLA-B*5701 can identify patients who are likely to experience an HSR and reduces the incidence of the reaction. OBJECTIVE: We assessed the intrinsic and practical value, from the US healthcare system perspective, of prospective HLA-B*5701 screening among a population of antiretroviral-naive patients without elevated risk factors for cardiovascular disease, plasma HIV RNA >100,000 copies/mL, or pre-existing renal insufficiency. METHODS: Two approaches were used to evaluate the costs and benefits of prospective screening. First, the efficiency of HLA-B*5701 screening compared with no screening prior to abacavir initiation (intrinsic value of screening) was evaluated using a 60-day decision-tree model. Next, the practical value of screening was assessed using a lifetime discrete-event simulation model that compared HLA-B*5701 screening prior to abacavir use versus initiation with a tenofovir-containing regimen. Screening-effectiveness parameters were taken from an open-label trial that incorporated screening prior to abacavir initiation and other published studies. Treatment efficacy was derived from clinical trials. Modelling assumptions, costs ($US, year 2007 values) and other parameters were derived from published sources, primary data analysis and expert opinion. Multiple one-way sensitivity and scenario analyses were performed to assess parameter uncertainty. The primary outcome measure for the short-term screening versus no screening analysis was cost per patient. For the long-term analysis, outcomes were presented as QALYs. Costs and effects were discounted at 3% per year. RESULTS: Over the first 60 days of treatment, prospective screening prior to abacavir initiation cost an additional $US17 per patient and avoided 537 HSRs per 10,000 patients. The per-patient cost of screening was sensitive to the cost of the genetic test, HSR costs and screening performance. In the lifetime model, screening-informed abacavir use was more effective and less costly than initiation with a tenofovir-containing regimen in the base case and in sensitivity analyses. CONCLUSIONS: Our results suggest that prospective HLA-B*5701 screening prior to abacavir initiation produces cost savings and should become a standard component of HIV care.

The cost-effectiveness of HLA-B*5701 genetic screening to guide initial antiretroviral therapy for HIV.

OBJECTIVE: To evaluate the clinical impact and cost-effectiveness of HLA-B*5701 testing to guide selection of first-line HIV regimens in the United States. DESIGN: Cost-effectiveness analysis using a simulation model of HIV disease. The prevalence of HLA-B*5701 and the probabilities of confirmed and unconfirmed severe systemic hypersensitivity reaction among patients taking abacavir testing HLA-B*5701 positive and negative were from the Prospective Randomized Evaluation of DNA Screening in a Clinical Trial study. The monthly costs of abacavir-based and tenofovir-based regimens were $1135 and $1139, respectively; similar virologic efficacy was assumed and this assumption was varied in sensitivity analysis. PATIENTS: Simulated cohort of patients initiating HIV therapy. INTERVENTIONS: The interventions are first-line abacavir, lamivudine, and efavirenz without pretreatment HLA-B*5701 testing; the same regimen with HLA-B*5701 testing; and first-line tenofovir, emtricitabine, and efavirenz. MAIN OUTCOME MEASURES: Quality-adjusted life years and lifetime medical costs discounted at 3% per annum, cost-effectiveness ratios ($/QALY). RESULTS: Abacavir-based treatment without HLA-B*5701 testing resulted in a projected 30.93 years life expectancy, 16.23 discounted quality-adjusted life years, and $472,200 discounted lifetime cost per person. HLA-B*5701 testing added 0.04 quality-adjusted months at an incremental cost of $110, resulting in a cost-effectiveness ratio of $36,700/QALY compared with no testing. Initiating treatment with a tenofovir-based regimen increased costs without improving quality-adjusted life expectancy. HLA-B*5701 testing remained the preferred strategy only if abacavir-based treatment had equal efficacy and cost less per month than tenofovir-based treatment. Results were also sensitive to the cost of HLA-B*5701 testing and the prevalence of HLA-B*5701. CONCLUSION: Pharmacogenetic testing for HLA-B*5701 is cost-effective only if abacavir-based treatment is as effective and costs less than tenofovir-based treatment.

Impact of long-term treatment with neurotoxic dideoxynucleoside antiretrovirals: implications for clinical care in resource-limited settings.

OBJECTIVES: A minority of HIV-infected patients taking an antiretroviral (ARV) regimen containing dideoxynucleosides (d-drugs) such as stavudine (d4T) and didanosine (DDI) experiences dose-limiting neuropathic pain and paraesthesias, usually within weeks of starting these drugs. Because d-drugs are among the few affordable options available in developing countries, continuing d-drug therapy would be a desirable strategy for many HIV-infected individuals. Therefore, we evaluated the safety of continuing d-drug therapy. METHODS: In a US cohort, we compared the rates of worsening neuropathic symptoms and signs in HIV-infected individuals on stable ARV regimens that did (n=252) or did not (n=250) include d-drugs. Rates of worsening were compared using proportional hazards model and the log-rank test. RESULTS: The risk ratios (RR) were not significantly larger for worsening neuropathy signs [0.94; 95% confidence interval (CI) 0.84-1.07] or symptoms (0.99; 95% CI 0.88-1.14) in patients taking d-drugs continuously compared to those not taking d-drugs. CONCLUSIONS: Continued d-drug exposure among patients tolerating an initial trial did not increase the risk of worsening neuropathy compared to non-d-drug-containing regimens. If applicable in developing countries, these findings suggest that in most patients d-drugs can be continued safely in the long term without increasing the risk of worsening neuropathy.

Cost-effectiveness analysis of HLA B*5701 genotyping in preventing abacavir hypersensitivity.

OBJECTIVE: Abacavir, a human immunodeficiency virus-1 (HIV-1) nucleoside-analogue reverse transcriptase inhibitor, causes severe hypersensitivity in 4-8% of patients. HLA B*5701 is a known genetic risk factor for abacavir hypersensitivity in Caucasians. Our aim was to confirm the presence of this genetic factor in our patients, and to determine whether genotyping for HLA B*5701 would be a cost-effective use of healthcare resources. METHODS: Patients with and without abacavir hypersensitivity were identified from a UK HIV clinic. Patients were genotyped for HLA B*5701, and pooled data used for calculation of test characteristics. The cost-effectiveness analysis incorporated the cost of testing, cost of treating abacavir hypersensitivity, and the cost and selection of alternative antiretroviral regimens. A probabilistic decision analytic model (comparing testing versus no testing) was formulated and Monte Carlo simulations performed. RESULTS: Of the abacavir hypersensitive patients, six (46%) were HLA B*5701 positive, compared to five (10%) of the non-hypersensitive patients (odds ratio 7.9 [95% confidence intervals 1.5-41.4], P = 0.006). Pooling of our data on HLA B*5701 with published data resulted in a pooled odds ratio of 29 (95% CI 6.4-132.3; P < 0.0001). The cost-effectiveness model demonstrated that depending on the choice of comparator, routine testing for HLA B*5701 ranged from being a dominant strategy (less expensive and more beneficial than not testing) to an incremental cost-effectiveness ratio (versus no testing) of Euro 22,811 per hypersensitivity reaction avoided. CONCLUSIONS: Abacavir hypersensitivity is associated with HLA B*5701, and pre-prescription pharmacogenetic testing for this appears to be a cost-effective use of healthcare resources.

[Simplification to lamivudine, zidovudine, and abacavir therapy: impact on adherence, clinical outcome, and economic issues]. / Simplificación con lamivudina, zidovudina y abacavir: repercusión sobre la adhrencia, resultados clínicos e impacto económico.

OBJECTIVES: To analyze the influence on adherence and clinical outcome of the replacement of a previous antiretroviral therapy to a simplified approach using zidovudine, lamivudine, and abacavir (Trizivir) and to assess its economic impact. METHODS: A retrospective study of 75 pretreated, HIV-infected adult patients who received Trizivir from May 2001 to December 2002. Adherence was assessed by dispensation records or medication counting, CD4 lymphocyte counts, and viral load before and six months after medication change was analyzed; finally, the cost of each therapy was assessed in order to calculate the economic impact of medication change. RESULTS: Mean adherence significantly increased a 2.5% after medication change; 16 more patients reached optimal adherence, with an NNT (number of patients requiring therapy change in order to obtain one more adherent) of 4.7. The number of patients with undetectable viral load remained almost similar, and mean CD4 cell counts stayed above 500 cells/mm3 in both periods of time. A great variability in incremental costs was seen, due to the varying costs of the previous treatments, and the influence of five intensification therapies using Trizivir. However, when only simplification regimens were analyzed such variability was reduced, and even became favorable in selected cases. CONCLUSIONS: Changing to a simplification therapy using Trizivir resulted in improved adherence, similar clinical outcomes, and a varying economic impact depending on previous antiretroviral therapy costs.