[Evidence-based therapeutic drug monitoring for indinavir]. / Niveau de preuve du suivi thérapeutique pharmacologique de l'indinavir.

The HIV protease inhibitor indinavir presents a wide inter-individual variability related to an intense hepatic metabolism. Published studies were analyzed to establish whether there is evidence that therapeutic drug monitoring of indinavir could improve patient care. It was reported that indinavir virological efficacy in HIV-infected patients with wild-type virus was significantly associated with trough concentrations > 100-150 ng/mL. Concerning the exposure-toxicity relationship, the risk of occurrence of nephrotoxicity was more frequently associated with trough concentrations > 500-1 000 ng/mL. Studies with concentration-controlled indinavir therapy suggest that therapeutic drug monitoring allows to achieve safe and effective concentrations, therefore, the level of evidence of the interest of indinavir therapeutic drug monitoring is highly recommended when indinavir is not associated with ritonavir and recommended when ritonavir is combined with ritonavir.

Economic analysis of initial HIV treatment. Efavirenz- versus indinavir-containing triple therapy.

OBJECTIVE: To compare the clinical and economic outcomes associated with triple therapy containing efavirenz or indinavir and 2 nucleoside reverse transcriptase inhibitors (NRTIs; zidovudine and lamivudine) in HIV-positive patients. DESIGN AND SETTING: An economic model based on viral load and CD4+ cell counts to predict long term outcomes such as progression to AIDS and AIDS-related death was developed and then analysed using data from a randomised clinical trial. Cost estimates from the healthcare system perspective were based on data from 6 state, all-payor databases, the AIDS Cost and Services Utilisation Study, and other literature. Analyses were carried out for time horizons between 5 and 15 years. PATIENTS AND INTERVENTIONS: HIV-positive patients with limited exposure to NRTIs. Initial regimens consisted of efavirenz or indinavir, each combined with 2 NRTIs. A maximum of 2 switches to other regimens was permitted. MAIN OUTCOME MEASURES AND RESULTS: The efavirenz-containing triple therapy regimen was predicted to prolong survival at a savings of up to 10,923 US dollars (1998 values) relative to initial therapy with the indinavir-containing regimen. Patients who receive efavirenz are expected to have 11% greater survival at 5 years and fewer treatment failures (28 vs 52%, at 2 years). Overall, the economic and health benefits predicted for the efavirenz-containing regimen were robust to reasonable variation in key parameters. CONCLUSIONS: The superior clinical trial outcomes for efavirenz-containing regimens should translate into substantial economic and health benefits.

[Antiretroviral therapy in HIV infection. Effects of the introduction of new drugs on health care expenditures, 1994-1999]. / Terapia antiretrovirale nell'infezione da HIV. Effetti indotti dalla introduzione di nuovi farmaci sulla spesa sanitaria 1994-1999.

The administration of antiretroviral compounds to our cohort of HIV-infected patients was assessed since 1994, on the ground of some epidemiological, clinical, and therapeutic variables. During the six-year study period, a significant increase of mean prescription rate of overall anti-HIV agents was observed, with a nearly 10-fold rise of mean prescribed daily doses per 1,000 patients-year. In particular, lamivudine and indinavir represented the most frequently administered drugs, among nucleoside analogues and protease inhibitors, respectively. A significant increase of the percentage of HIV-infected patients undergoing combined antiretroviral therapy (79.3% in 1999), and the mean number of drugs prescribed per patient (3.02 in 1999), was concurrently detected. The progressive changes of antiretroviral therapy guidelines were responsible for a nearly 16-fold increase of expenditures directly related to antiretroviral drug administration in 1999 compared with 1994 (with over 41% of costs related to protease inhibitors). On the other hand, a substantial modification of HIV disease evolution occurred in our patient cohort in terms of absolute morbidity and mortality figures, as expressed by a drop of notified AIDS cases and AIDS-related deaths ranging from 2.5 to 5 times, during the considered period.

[Cost effectiveness analysis of highly active antiretroviral therapy in HIV asymptomatic patients]. / Análisis coste-efectividad del tratamiento antirretroviral de gran actividad en pacientes infectados por el VIH asintomáticos.

BACKGROUND: Assessment of cost and effectiveness in highly active antiretroviral therapy (HAART) in HIV asymptomatic patients. PATIENTS AND METHODS: A cohort of several asymptomatic HIV-infected patients were observed under real practice and treated with two nucleosid analogues (AN) of which therapy was modified. A protease inhibitor (PI) was added and at least one AN was changed (or not), following the current clinical recommendations (1997). Data on direct cost (drug cost, visits and clinical procedures) were then recorded both three and six months after the beginning of the study. Data on effectiveness (percentage of patients with undetectable levels of viral load) and quality of life were next measured according to the EuroQol, and recorded at the same time. All patients used a monthly diary to keep record of resource consumption and quality of life progress. RESULTS: All treatment regimens were effective in lowering the viral load and improve quality of life. The less expensive HAART was AZT + 3TC + IND (1,037,757 pesetas) and AZT + ddl + IND (1,045,339 pesetas), but both were the least effective to reduce patient's viral load to undetectable levels (52.7 and 57.7% respectively); meanwhile d4T + 3TC + IND (1,188,177 pesetas) and d4T + ddl + IND (1,212,285 pesetas) were more expensive but more effective (67.9 and 66% respectively). Cost-effectiveness ratios ranged between 9,896 and 13,122 pesetas. There was no statistically significant differences in quality of life among the different HAART regimens. CONCLUSIONS: HAART implementation is effective in reducing patients' viral load to undetectable levels and to slightly improve their quality of life after six months. Costs and effectiveness vary according to the type of HAART treatment used.

Hospitalizations and costs of treatment for protease inhibitor-based regimens in patients with very advanced HIV-infection (CD4 < 50/mm(3)).

PURPOSE: To describe the cost of hospitalization and treatment in patients with very advanced disease who tart different regimens based on a protease inhibitor (PI). METHOD: An observational retrospective analysis was performed on data from a 48-week randomized, multicenter study. Analysis was based on a subgroup of centers that were geographically defined. Costs of ordinary hospital admissions and of antiretroviral treatment were considered. Incidence of hospitalization and number of days free from hospitalization during the period of observation were calculated. Cost and hospitalization measures were compared among patients receiving three different therapeutic regimens: only PI, PI plus one nucleoside, or PI plus two nucleosides. A multivariate analysis was used to assess cost differences, controlling for variables potentially able to influence outcome. RESULTS: Overall, among 166 patients starting PI (PI plus two nucleosides, 71;PI plus one nucleoside, 65; only PI, 30), 162 ordinary hospital admissions were observed during about 1 year of follow-up. Monthly rates of admission per person and incidence of first hospitalization on 100 person-months showed a clear inverse relationship with the number of drugs comprising the baseline treatment regimen, with the lower rates for the triple therapy group (0.06 and 3.9, respectively), intermediate values for the dual therapy group (0.10 and 8.1, respectively), and higher rates for the PI monotherapy group (0.15 and 13.7, respectively). The average number of days free from hospitalization per month was 29.5 in the triple therapy group, 28.6 in the dual therapy group, and 27.9 in the monotherapy group. The results of cost analysis showed, despite higher cost of antiretroviral treatment, that global costs were progressively lower using regimens of increasing potency: Compared to PI monotherapy, global cost (costs of antiretroviral treatment and of hospitalizations combined) per month per patient was 31.9% lower for the triple therapy group and 19.3% lower for the dual therapy. Global cost for the triple therapy was 15.7% lower compared to global cost for dual therapy. After adjustment for CD4 count, AIDS status, and Karnofsky score, both hospitalization costs and global costs were significantly lower for triple therapy compared to monotherapy (p =.002 and.039, respectively). CONCLUSION: In advanced and nucleoside-experienced patients, PI-containing regimens have a differential impact according to the overall strength of the regimen, with the best effects on both hospitalizations and treatment costs obtained using PI within potent combination regimens.

Modeling the long-term outcomes and costs of HIV antiretroviral therapy using HIV RNA levels: application to a clinical trial.

A model was developed to gain insight into the potential clinical and economic impact of antiretroviral therapy for HIV-infected patients. Observed HIV RNA levels and CD4 cell counts are used in the model to estimate the probability that an individual progresses from asymptomatic infection to the first AIDS-defining illness and death and to estimate the total net cost of care and long-term cost-effectiveness of antiretroviral therapy. The model was applied to patients in a clinical trial (Merck protocol 035) that compared the surrogate marker response to triple therapy with indinavir (IDV; 800 mg every 8 hr) plus zidovudine (ZDV; 200 mg every 8 hr) plus lamivudine (3TC; 150 mg twice a day) to double therapy with ZDV+3TC. The model projected that for an individual without AIDS who received triple therapy the progression to AIDS and death would be delayed more than for a patient who received double therapy with ZDV+3TC if no other treatment options were offered. Because of this delay in disease progression, the total discounted cost over the initial 5-year period was projected to be $5100 lower for patients who received triple therapy compared with double therapy if suppression with triple therapy lasts up to 3 years. If suppression with triple therapy lasts up to 5 years, costs were projected to be higher with the triple combination, but 81% of the cost is offset by lower disease costs as a result of fewer patients progressing to AIDS. Over 20 years, total discounted cost was projected to be higher for the triple-therapy regimen primarily because of a longer estimated survival time. At 20 years, the incremental cost per life-year gained by adding IDV to a ZDV+3TC regimen was estimated at $13,229, which is well within the range of other widely accepted medical interventions.

HIV-1 protease inhibitors. A review for clinicians.

OBJECTIVE: The clinical care of people infected with human immunodeficiency virus (HIV) has been substantially affected by the introduction of HIV-specific protease inhibitors (PIs). The 4 PIs available are saquinavir mesylate, ritonavir, indinavir sulfate, and nelfinavir mesylate. Comparison studies have not been reported; therefore, an assessment of the available data to aid clinicians and patients in choosing appropriate treatment will be presented. DATA SOURCES: A systematic review of peer-reviewed publications, abstracts from national and international conferences, and product registration information through September 1996. STUDY SELECTION AND DATA EXTRACTION: Criteria used to select studies include their relevance to PIs, having been published in the English language, and pertinence for clinicians. Data quality and validity included the venue of the publication and relevance to clinical care. DATA SYNTHESIS: Oral adminstration of ritonavir, indinavir, or nelfinavir generates sustainable drug serum levels to effectively inhibit the protease enzyme; however, saquinavir may not generate sustained levels necessary to inhibit the protease enzyme. Patients treated with ritonavir, indinavir, or nelfinavir experience similar reductions in viral load and increases in CD4+ lymphocytes; smaller effects occur among those treated with saquinavir. Two randomized placebo-controlled studies conducted among patients with severe immune system suppression and substantial zidovudine treatment experience demonstrated reduced HIV disease progression and reduced mortality with PI treatment. Genotypic resistance to PIs occurs; the clinical relevance of resistance is unclear. The costs of these agents including required monitoring impose new and substantial costs. CONCLUSIONS: The PIs have emerged as critical drugs for people with HIV infection. Optimal use involves combination with reverse transcriptase inhibitors. Resistance develops to each agent, and cross-resistance is likely. These agents must be used at full doses with attention to ensuring patient compliance. The expense of these agents may be offset by forestalling disease progression and death and returning people to productive life. Selecting the initial PI must be individualized, and factors to consider include proven activity, possible toxicities, dosing regimens, drug interactions, and costs.