[Low-dose heparin and acetyl-salicylic acid after elective operations on the hip joint (author's transl)]

Collaborative overview of randomised trials of antiplatelet therapy--I: Prevention of death, myocardial infarction, and stroke by prolonged antiplatelet therapy in various categories of patients. Antiplatelet Trialists' Collaboration

OBJECTIVE

To determine the effects of "prolonged" antiplatelet therapy (that is, given for one month or more) on "vascular events" (non-fatal myocardial infarctions, non-fatal strokes, or vascular deaths) in various categories of patients.

DESIGN

Overviews of 145 randomised trials of "prolonged" antiplatelet therapy versus control and 29 randomised comparisons between such antiplatelet regimens.

SETTING

Randomised trials that could have been available by March 1990.

SUBJECTS

Trials of antiplatelet therapy versus control included about 70,000 "high risk" patients (that is, with some vascular disease or other condition implying an increased risk of occlusive vascular disease) and 30,000 "low risk" subjects from the general population. Direct comparisons of different antiplatelet regimens involved about 10,000 high risk patients.

RESULTS

In each of four main high risk categories of patients antiplatelet therapy was definitely protective. The percentages of patients suffering a vascular event among those allocated antiplatelet therapy versus appropriately adjusted control percentages (and mean scheduled treatment durations and net absolute benefits) were: (a) among about 20,000 patients with acute myocardial infarction, 10% antiplatelet therapy v 14% control (one month benefit about 40 vascular events avoided per 1000 patients treated (2P < 0.00001)); (b) among about 20,000 patients with a past history of myocardial infarction, 13% antiplatelet therapy v 17% control (two year benefit about 40/1000 (2P < 0.00001)); (c) among about 10,000 patients with a past history of stroke or transient ischaemic attack, 18% antiplatelet therapy v 22% control (three year benefit about 40/1000 (2P < 0.00001)); (d) among about 20,000 patients with some other relevant medical history (unstable angina, stable angina, vascular surgery, angioplasty, atrial fibrillation, valvular disease, peripheral vascular disease, etc), 9% v 14% in 4000 patients with unstable angina (six month benefit about 50/1000 (2P < 0.00001)) and 6% v 8% in 16,000 other high risk patients (one year benefit about 20/1000 (2P < 0.00001)). Reductions in vascular events were about one quarter in each of these four main categories and were separately statistically significant in middle age and old age, in men and women, in hypertensive and normotensive patients, and in diabetic and nondiabetic patients. Taking all high risk patients together showed reductions of about one third in non-fatal myocardial infarction, about one third in non-fatal stroke, and about one third in vascular death (each 2P < 0.00001). There was no evidence that non-vascular deaths were increased, so in each of the four main high risk categories overall mortality was significantly reduced. The most widely tested antiplatelet regimen was "medium dose" (75-325 mg/day) aspirin. Doses throughout this range seemed similarly effective (although in an acute emergency it might be prudent to use an initial dose of 160-325 mg rather than about 75 mg). There was no appreciable evidence that either a higher aspirin dose or any other antiplatelet regimen was more effective than medium dose aspirin in preventing vascular events. The optimal duration of treatment for patients with a past history of myocardial infarction, stroke, or transient ischaemic attack could not be determined directly because most trials lasted only one, two, or three years (average about two years). Nevertheless, there was significant (2P < 0.0001) further benefit between the end of year 1 and the end of year 3, suggesting that longer treatment might well be more effective. Among low risk recipients of "primary prevention" a significant reduction of one third in non-fatal myocardial infarction was, however, accompanied by a non-significant increase in stroke. Furthermore, the absolute reduction in vascular events was much smaller than for high risk patients despite a much longer treatment period (4.4% antiplatelet therapy v 4.8% control; five year

[Prevention of thromboembolism in para-articular femoral fractures of the hip--results of a prospective randomized study of heparin-DHE and ASS-DHE]

The effectiveness of prophylaxis of thromboembolism either by acetyl-salicylic-acid (ASA) 0.5 g + dihydroergotamin (DHE) 2.5 mg three times a day or by Heparin 5000 IU + 0.5 mg DHE (HDHE) three times a day was compared in 404 patients, elder than 55 years, with fractures close by the hip joint. Effectiveness was proved daily clinical controls, perfusion scintigraphy on the day after admission, the fourth postoperative day and the day before discharge and by autopsy of the died patients. Clinical manifest thrombosis were seen on the operated legs in the HDHE-group in 7.6% of the patients, in ASA-DHE-group in 15.6%, on the not operated leg under prophylaxis by HDHE in 3.8%, by ASA-DHE in 4.1% of the patients. Increased postoperative bleeding could be found under HDHE in 16.1% of the patients, under ASA-DHE in 9.3% of the patients, wound haematoma in 9.5% under HDHE and in 5.7% of the patients of the ASA-DHE-group. Superficial wound infections occurred under HDHE in 8.1%, under ASA-DHE in 5.7% of the patients, deep infections under HDHE in 0.5% and under ASA-DHE in 1.6% of the patients. Gastrointestinal bleeding under HDHE in 0.5% of the cases and under ASA-DHE in 3.1% of the cases. Prophylaxis had to be discharged in 7.6% of the patients of the HDHE-group and of 19.7% of the ASA-DHE-group. Pathologic perfusion scars should be found in 54.0% of the patients of the HDHE-group and in 54.9% of the ASA-DHE-group. Pulmonal perfusion became worse despite of prophylaxis by HDHE in 15.6% of the cases and despite prophylaxis with ASA-DHE in 17.6%. Pulmonal perfusion became better under HDHE in 11.9% and under ASA-DHE in 12.4% of the cases. The mortality was 9.7%. Fatal thromboembolism occurred under HDHE in three patients (1.4%) and under ASA-DHE in three patients too (1.6%), after subcapital fractures in 0.5%, after pertrochanteric fractures in 2.1% and after subtrochanteric fractures in 6.25% of the patients without any significant difference between the two groups of prophylaxis. Fatal gastrointestinal bleeding had to be remarked in 1.0% of the patients of the HDHE-group and in 2.1% of the ASA-DHE-group, fatal infections in 0.5% of the patients of the HDHE-group and in 1.6% of the ASA-DHE-group. Fatal cardinal infarction could be seen under HDHE in 1.9% of the patients, under ASA-DHE no fatal cardial infarction occurred.(ABSTRACT TRUNCATED AT 400 WORDS)

Thromboembolism after hip surgery

Since 1973 a prospective trial of antithrombotic agents for the prophylaxis of deep venous thrombosis and pulmonary embolism was undertaken in 386 high risk patients. Five drugs were employed: 1. A combination of aspirin and dipyridamol (95 patients); 2. Dextran 60 (43 patients); 3. Dihydroergotamine (61 patients); 4. Low dose heparin (63 patients); 5. A combination of dihydroergotamine and low dose heparin (twice daily in 61 patients and three times daily in 63 patients). The patients were investigated by I125 fibrinogen uptake test, phlebography, lung scan and careful clinical evaluation before and after operation. In cases of established thrombosis simultaneous anticoagulation with heparin and coumadin was started. In the first group, 32 (34%) thromboses and three pulmonary emboli were detected of which one patient died. In the dextran group, 24 patients (54%) developed thrombosis and there were no fatal pulmonary emboli. In the low dose heparin group we detected 29 (46%) thromboses and three pulmonary emboli. Only the combination of low dose heparin and dihydroergotamine significantly reduced the incidence of thromboembolic complications-15 (25%) thromboses and no pulmonary emboli. The application of this combination three times a day showed no further improvement but more haemorrhagic complications appeared. Since 1975 no fatal pulmonary emboli have occurred in 720 patients undergoing total hip replacement.

[Clinical and in-vitro studies of the therapeutical range of acetylsalicylic-acid to prevent deep vein thrombosis (author's transl)]

In three consecutive studies, acetylsalicyliclysine using the dosages 0.9 g/48 h, 1.8 g/24 h and 3.6 g/24 h, was examined in order to see its effect in preventing deep vein thrombosis (DVT) after elective hip joint surgery. DVT was diagnosed by the 125-i-fibrinogen-test. No reduction of postoperative DVT was found under any of the administered AS-lysine dosages. The collagen-induced platelet aggregation was significantly decreased in all three groups. However, under the low AS-lysine dosages, aggregation was less inhibited with the incidence of DVT than without DVT. In the group with the 3.6 g-dosage, aggregation was maximally inhibited, without any significant difference related to the occurrence of DVT. The results reveal no therapeutic range of AS-lysine to prevent postoperative venous thrombosis.