Effectiveness and cost effectiveness of single bolus treatment with abciximab (Reo Pro) in preventing restenosis following percutaneous transluminal coronary angioplasty in high risk patients

Current literature for evidence-based infrainguinal endovascular treatment

With the proliferation of devices and techniques for lower extremity endovascular revascularization, treatment decisions become increasingly difficult as only limited experience with these new technologies is available for review. This monograph attempts to define the current state of the literature available to guide endovascular treatment of superficial artery disease, and to provide a baseline for future studies.

Impact of abciximab and coronary stenting on outcomes and costs of percutaneous coronary interventions in a community hospital

OBJECTIVE

To assess costs and outcomes of coronary stenting and balloon angioplasty with and without adjunctive treatment with abciximab for 3758 consecutive elective percutaneous coronary interventions at a single community center over the 2.5-year period between 1 January 1995 and 30 June 1997.

RESULTS

Abciximab was more common among patients who had recently suffered myocardial infarction, patients with unstable angina, and patients with more complex coronary lesions. Use of abciximab in conjunction with balloon angioplasty or stenting and stenting alone was associated with significant reductions in incidence of major adverse cardiovascular events in hospital. Multivariate analysis indicated that use of abciximab and stenting were associated with significant independent effects on risk of an event. Hospital costs were increased for patients administered abciximab, treated with stenting, or both. Total costs and costs inclusive of those incurred in catheterization laboratory and pharmacy increased significantly with increasing complexity of lesions. Multivariate regression analysis (baseline cost US$5621) identified death (US$16098), emergency revascularization (US$13678), usage of multiple stents (US$1423 for each stent), and use of abciximab (US$1269) as independent predictors of a greater cost. One-year follow-up revealed significant differences among treatment strategies in terms of risk of need for subsequent revascularization procedures. Lack of stenting but not use of abciximab was identified as a significant predictor of need for repeat revascularization procedures.

CONCLUSIONS

Our findings are in general agreement with cost analyses of use of abciximab for populations in clinical trials and suggest that improvements of early clinical outcome with abciximab treatment and stenting justify the incremental cost of treatment in a community hospital setting.

Abciximab inhibits the migration and invasion potential of human coronary artery smooth muscle cells

In the EPIC trial, high-risk patients received the integrin receptor antagonist abciximab v placebo during and for 12 h following percutaneous coronary intervention with a significant 23% decrease of repeat revascularisation at 6 months. However, EPILOG and CAPTURE trials could not confirm these promising long-term results. Recently presented data from the EPISTENT trial suggested a beneficial effect of abciximab on restenosis in patients with diabetes. Based on these divergent results the aim of this study was to test whether alpha v beta 3 receptor blockade by abciximab could cause inhibition of human coronary smooth muscle cell (hcSMC) proliferation, migration, and invasion which represent crucial steps during restenosis development. In contrast to quiescent hcSMCs, proliferating cells were capable to migrate towards chemoattractive stimuli and even capable to invade through a basement membrane equivalent. Abciximab and LM609, an alpha v beta 3 specific inhibiting antibody, caused only a modest dose-dependent inhibition of hcSMC proliferation. On the contrary, the chemotactic and invasive potential of hcSMCs was significantly inhibited by abciximab administration 24 h prior to and during migration. (IC(50)=33.0 microg/ml for chemotaxis and IC(50)=0.5 microg/ml for invasion). For LM609 similar results were obtained. Administration of the drugs just during migration without pretreatment inhibited migration equally but invasion to a lower extent (abciximab: IC(50)=32.6 microg/ml for chemotaxis and IC(50)=44.9 microg/ml for invasion; LM609 IC(50)=3.1 microg/ml for chemotaxis and IC(50)=2.0 microg/ml for invasion). The attachment to the extracellular matrix proteins collagen I, collagen IV, laminin and vitronectin was not influenced. Pretreatment for 24 h with abciximab or LM609 did not cause a downregulation of the alpha v beta 3-integrin receptor. The results of this study indicate that the alpha v beta 3 antagonist abciximab is a potent inhibitor of hcSMC migration and invasion which could explain the observed lower reintervention rate after PTCA and stent implantation.

Cost effectiveness of abciximab during routine medical practice

OBJECTIVE

To estimate the cost per ischaemic event (death, nonfatal myocardial infarction, subsequent revascularisation procedure) avoided at 6 months in high risk patients undergoing coronary revascularisation treated with abciximab during routine medical care.

DESIGN

Retrospective, matched cohort design.

SETTING

University teaching hospital.

PATIENTS

62 abciximab-treated patients and 62 patients not treated with abciximab with high risk coronary lesions were matched according to gender, hyperlipidaemia, diabetes mellitus and stenting.

MAIN OUTCOME MEASURES

Using a third-party payer's perspective, an incremental cost-effectiveness ratio (ICER) was computed as the cost per ischaemic event avoided over 6 months. Fieller's theorem was used to estimate confidence sets and confidence ellipses were generated to visually represent the variability in the data.

RESULTS

At 6 months, abciximab-treated patients experienced an approximately 40% lower rate of ischaemic events (16.1 vs 27.4%; p = 0.128). The point estimate of the ICER was $US21,789 per ischaemic event avoided. Fieller's theorem resulted in a 95% confidence set consisting of 2 half-lines (-infinity to -$US115,461) and ($US391 to +infinity), reflecting the finding that the ICER denominator was not significantly different from zero at the p = 0.05 level.

CONCLUSIONS

In high risk patients treated during routine care, the effectiveness of abciximab was consistent with efficacy rates from clinical trials. However, abciximab-treated patients remained approximately $US2400 more costly at 6 months.

Abciximab. A pharmacoeconomic review of its use in percutaneous coronary revascularisation

Abciximab is a monoclonal antibody fragment that inhibits platelet aggregation through antagonism of glycoprotein IIb/IIIa. The drug is used in conjunction with heparin and aspirin to prevent ischaemic complications associated with percutaneous coronary revascularisation in patients with coronary heart disease. Large and well designed clinical studies have shown abciximab, as an adjunct to aspirin and heparin, to reduce by around one-third to one-half the incidence of ischaemic complications within 30 days of percutaneous coronary revascularisation. Use of the drug appears advantageous in patients at high risk, and abciximab also reduces complications in patients undergoing coronary stenting, although the drug does not appear to inhibit restenotic tissue volume within stents. Longer term benefit has also been reported, with emerging 1-year data from a study in patients at all levels of risk showing reductions in a composite end-point of death, myocardial infarction (MI) or urgent repeat revascularisation. Three-year benefit has been reported in high risk patients. Meta-analysis results, and 1-year data from patients receiving stents, have shown reduced mortality with abciximab. Abciximab therapy had an incremental cost over standard therapy from a hospital perspective of $US293 per patient (1991/1992 values) over 6 months in a prospective economic substudy from a major US clinical trial of the drug in high risk patients. Abciximab was cost saving in patients with unstable angina. A mean net cost of hospitalisation of $US476 per patients (1995 costs) has been shown in a further study in patients with a broad range of levels of risk, and observational data indicate reduced duration of hospitalisation with abciximab. Cost-effectiveness data favoured abciximab with aspirin and heparin over a 6-month period in Spanish and Dutch analyses in which data from the above trial were combined with local cost data, but not in an Australian analysis. Subgroup analyses have indicated enhanced cost effectiveness in high risk patients. Available data also show clinical benefit and cost effectiveness of abciximab therapy in conjunction with coronary stent placement.

CONCLUSIONS

Data indicate intravenous bolus plus 12-hour infusion regimens of abciximab to be economically viable in patients at high or low risk of ischaemic complications after percutaneous coronary revascularisation. The drug has been shown to be cost effective in patients receiving the drug in conjunction with coronary stents, and subgroup analyses indicate additional cost effectiveness in certain groups of patients at high risk of ischaemic complications (notably those with acute MI and unstable angina).

Abciximab. An updated review of its use in ischaemic heart disease

Abciximab is a glycoprotein IIb/IIIa receptor antagonist that has proven to be of significant clinical value in improving patient outcome after percutaneous coronary revascularisation. Primarily, the drug inhibits platelet aggregation, but it may also have anticoagulant activity and other beneficial effects, such as inhibiting migration and promoting apoptosis of smooth muscle cells. Large well designed studies have found administration of abciximab (as an adjunct to heparin and aspirin) during percutaneous coronary revascularisation to significantly reduce the incidence of ischaemic complications occurring in the 30 days after the procedure. Significant benefit, particularly on the incidence of myocardial infarction, was still evident after 6 months in 2 of 4 major trials. Abciximab provides particular benefit in patients with unstable angina or myocardial infarction who are undergoing percutaneous coronary revascularisation. The benefits of the drug are additive to those achieved with coronary stenting. Very preliminary data suggest that abciximab may improve coronary blood flow after myocardial infarction and allow reperfusion to be achieved with reduced thrombolytic doses. Caution is required to minimise the risk of bleeding complications with the use of abciximab in combination with heparin and aspirin. Careful patient selection, use of an appropriate heparin regimen, early vascular sheath removal and meticulous femoral artery access site care are recommended. Thrombocytopenia can occur with abciximab treatment, but severe cases are uncommon (< 2% of patients) and can be treated with platelet transfusions. The high acquisition cost of abciximab may be partly or fully offset by the costs averted by the reduced incidence of ischaemic complications and need for urgent and/or repeat revascularisation in high risk patients who receive the drug. However, if bleeding complications occur, this adds to treatment costs. Cost effectiveness analyses generally support the use of abciximab in high risk patients.

CONCLUSIONS

Abciximab can be recommended for the prevention of acute ischaemic events in most patients undergoing percutaneous coronary revascularisation, but careful patient selection and strict adherence to the recommended treatment protocol are required to reduce the risk of bleeding complications and thrombocytopenia. Its use in high risk patients is largely supported by pharmacoeconomic data. Further pharmacoeconomic information is needed to establish the drug as a standard of care for all patient groups. The indications for abciximab are likely to expand as more data on its use in acute coronary syndromes become available.