Antiplatelet agents – clopidogrel (Plavix)

Findings by SBU Alert

This is a translation of version 1, published on October 29, 1999. The latest version of this report is not available in English.

Clopidogrel is a recently approved drug which helps prevent the formation of blood clots in vascular diseases resulting from atherosclerosis. There is strong evidence that drugs which inhibit blood clots, eg, acetylsalicylic acid (ASA), have prophylactic effects in patients with atherosclerotic disease. The effects of clopidogrel have been compared to the effects of ASA in a randomized, controlled study involving over 19 000 patients. The diseases targeted for prevention were stroke, myocardial infarction, and fatal cardiovascular disease. After a followup of 1.9 years, the authors found a 0.5 per cent absolute difference favoring clopidogrel. Hence, 196 patients must be treated with clopidogrel for one year to prevent one additional case of the diseases listed above (beyond the number of cases prevented by ASA). The cost of preventing one case would be approximately 1.2 million SEK.

There is good* evidence on the short-term effects of treatment. The long-term results of treatment exceeding one to three years are not available, nor are published findings on the cost-effectiveness of treatment.

The annual cost per patient for clopidogrel is approximately 6 000 SEK higher than for ASA. A shift from ASA to clopidogrel would provide a marginal health benefit, but would substantially increase the costs for drugs.

*This assessment by SBU Alert uses a 4-point scale to grade the quality and evidence of the scientific documentation. The grades indicate: (1) good, (2) moderate, (3) poor, or (4) no scientific evidence on the subject.

This summary is based on a report prepared at SBU in collaboration with Agneta Björck Linné, Lic Pharmacist, Malmö University Hospital, Mona Britton, Assoc Prof, SBU, Ann Einerth, MA Econ, Federation of Swedish County Councils, and Hans Liedholm, Assoc Prof, Malmö University Hospital.

Alert is a joint effort by the Swedish Council on Technology Assessment in Health Care (SBU), the Medical Products Agency, the National Board of Health and Welfare, and the Federation of Swedish County Councils.

References

1. Caprie Steering Committee. A randomised, blinded trial of clopidogrel versus aspirin in patients at risk of ischaemic events (CAPRIE), Lancet 1996;348:1329-39.
2. Diener HC, Cunha L, Forbes C, Sivenius J, Smets P, Lowenthal A. European Stroke Prevention Study 2. Dipyridamol and acetylsalicylic acid in the secondary prevention of stroke. J Neurol Sci 1996;143:1-13.
3. Overell JR, Walker A, Weir CJ, Lees KR. The cost effectiveness of clopidogrel and the combination of aspirin and dipyridamole in stroke prevention (abstr.) Cerebrovasc Dis 1999;9(suppl 1):66.