SummaryA high incidence of post-discharge venous thromboembolism in orthopaedic surgery patients has been recently reported drawing further attention to the unresolved issue of the optimal duration of the pharmacological prophylaxis. We performed an overview analysis in order to evaluate the incidence of late occurring clinically overt venous thromboembolism in major orthopaedic surgery patients discharged from the hospital with a negative venography and without further pharmacological prophylaxis. We selected the studies published from January 1974 to December 1995 on the prophylaxis of venous thromboembolism after major orthopaedic surgery fulfilling the following criteria: 1) adoption of pharmacological prophylaxis, 2) performing of a bilateral venography before discharge, 3) interruption of pharmacological prophylaxis at discharge in patients with negative venography, and 4) post-discharge follow-up of the patients for at least four weeks. Out of 31 identified studies, 13 fulfilled the overview criteria. The total number of evaluated patients was 4120. An adequate venography was obtained in 3469 patients (84.1%). In the 2361 patients with negative venography (68.1%), 30 episodes of symptomatic venous thromboembolism after hospital discharge were reported with a resulting cumulative incidence of 1.27% (95% C.I. 0.82-1.72) and a weighted mean incidence of 1.52% (95% C.I. 1.05-1.95). Six cases of pulmonary embolism were reported. Our overview showed a low incidence of clinically overt venous thromboembolism at follow-up in major orthopaedic surgery patients discharged with negative venography. Extending pharmacological prophylaxis in these patients does not appear to be justified. Venous thrombi leading to hospital re-admission are likely to be present but asymptomatic at the time of discharge. Future research should be directed toward improving the accuracy of non invasive diagnostic methods in order to replace venography in the screening of asymptomatic post-operative deep vein thrombosis.

SummaryThis double-blind, randomised, controlled study examined the effect of a daily dosage of 3 g n-3 polyunsaturated fatty acids (n-3 PUFA) on plasma lipids and some haemostatic factors in 40 patients with chronic atherosclerotic diseases. Serum lipids, factor VII, tissue factor pathway inhibitor (TFPI) and prothrombin activation fragment 1+2 (F1+2) were measured at baseline and after 2, 8, and 16-week supplementation of either n-3 PUFA or com oil. Administration of n-3 PUFA promptly lowered serum triglycerides and increased LDL-cholesterol (-32% and +33%, respectively, after 2 weeks of treatment) while a significant increase (+31%) in HDL-cholesterol was documented at the end of the observation period. Treatment with n-3 PUFA induced a progressive significant increase of TFPI plasma levels (+21% after 16 weeks; p = 0.029). TFPI activity was significantly correlated with LDL-cholesterol, and multiple stepwise regression analysis showed that LDL-cholesterol was the most important predictor of TFPI activity. Plasma levels of the inhibitor showed also a very high parallelism in their trend over time (ANOVA model for homogeneity of slopes) with both HDL-cholesterol (p = 0.82) and LDL-cholesterol (p = 0.67). Patients treated with n-PUFA also showed a significant reduction of F1+2 plasma levels (p = 0.016) while no significant changes were detected in plasma factor VII clotting activity. Lipid and haemostatic parameters were not modified at any study time in patients receiving corn oil as placebo. The results of this study confirm the effects of n-3 PUFA administration on plasma lipids and show that in patients with chronic atherosclerotic disease a 16-week supplementation with these compounds induces a small but statistically significant increase of TFPI plasma levels with a parallel down-regulation of the extrinsic pathway of blood coagulation which may be relevant to the antithrombotic activity of fish diet and fish oil derivatives.

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