Antiplatelet treatment in elderly people with transient ischaemic attacks or ischaemic strokesBMJ 1995; 310 doi: https://doi.org/10.1136/bmj.310.6971.25 (Published 07 January 1995) Cite this as: BMJ 1995;310:25
- Juhani Sivenius, associate professora,
- Paavo J Riekkinen Sr, professor of neurosciencea,
- Markku Laakso, professorb
- a Department of Neurology, University of Kuopio, University Hospital, PO Box 1627, SF-70211 Kuopio, Finland
- b Department of Medicine, University of Kuopio, Kuopio, Finland
- Correspondence to: Dr Sivenius.
- Accepted 5 October 1994
Strokes and transient ischaemic attacks become more common with advancing age, and their prognosis becomes worse. Because of the increase in the number of elderly subjects in most Western societies, atherothrombotic cerebrovascular disease is a significant health problem. It is important, therefore, to find effective treatments for both primary and secondary prevention.
The Antiplatelet Trialists' Collaboration found that the reduction in vascular events as an end point in patients with a previous stroke or transient ischaemic attack was 22%.1 Antiplatelet drugs were equally effective in patients older and younger than 65 years, a result that was also seen in the European stroke prevention study.2 No study has, however, investigated the protective effect of antiplatelet drugs in patients older than 70 or 80. We analysed a subgroup of the 1306 Finnish patients participating in the European stroke prevention study to evaluate the effectiveness of drug treatment in different age groups.
Subjects, methods, and results
The European stroke prevention study investigated whether the combination of 75 mg dipyridamole and 330 mg aspirin three times a day was more effective than placebo in the secondary prevention of stroke or death in patients with previous ischaemic cerebral lesions. It was a randomised, placebo controlled, double blind study with parallel groups. Sixteen centres from six countries participated. The treatment groups showed a 33% decrease in the combined end point (the sum of stroke and death) compared with the placebo group.3 The study design has been described in more detail elsewhere.2 3 Of the 2500 patients recruited, 1306 were from a single centre in Kuopio, east Finland, representing 52% of the whole study population. Of these, 40% had had a transient ischaemic attack and 60% a stroke as the qualifying event for entry to the trial.
The combined end point in statistical analyses was the sum of stroke and death from any cause. Results from all randomised patients were studied using intention to treat analysis. Survival curves were plotted by the actuarial method, and significance was calculated using Lee-Desu statistics.
The table shows the effect of age on the risk of stroke or death as the reduction in the combined end point by age group. There was a clear increase in the risk of stroke or death with increasing age in the placebo group. In patients younger than 50 the frequency of the combined end point during two years of follow up was 16%, increasing to 60% in patients older than 80. In the active treatment group, however, the frequency of the end point increased from 10% to only 20%. The reduction in the combined end point varied from 30% to 66.7%, with the highest percentage reduction occurring in the oldest age group. The difference between the treatment groups was significant in all age groups of 50 and over. The treatment effect was independent of the length of follow up in all age groups (Cox regression analysis, data not shown). The effect of treatment was probably not influenced by the adverse effects of the drugs used because the drop out rate due to side effects decreased with increasing age.
The incidence of ischaemic events increases with advancing age. Furthermore, the survival rate of elderly patients is lower than that of younger patients. This difference could be partly due to differences in the risk factor profiles of old and young patients. Accordingly, the frequency of total end point events clearly increased with increasing age above 60.
This study clearly shows the efficacy of antithrombotic treatment in patients with a previous history of transient ischaemic attacks or a stroke, even in those older than 80. Although there was also a noticeable reduction in end point in patients younger than 50, this reduction was not significant, possibly owing to a small number of patients. We conclude that patients with transient ischaemic attacks and strokes should have secondary prevention with antithrombotic treatment regardless of age.
We thank Pirjo Halonen of the statistical centre of the University of Kuopio for his help with analysis.