ArticlesRisk of deep-venous thrombosis after hospital discharge in patients having undergone total hip replacement: double-blind randomised comparison of enoxaparin versus placebo
Introduction
The risks of deep-venous thrombosis (DVT) and pulmonary embolism–complications that occur frequently after total hip replacement (THR) surgery–can be reduced by effective antithrombotic prophylaxis. Prophylaxis is commonly stopped when the patient is discharged from hospital, a practice based largely on convenience. However, current trends for shorter postoperative care in hospital are a concern because patients are discharged while at risk of postoperative venous thromboembolism. Johnson et al1 assessed the outcome of 7959 patients after THR surgery who received various forms of prophylaxis. They found that 83 (1·04%) patients had fatal pulmonary embolism, confirmed at necropsy in most. Of these cases, 9·7% occurred during the first postoperative week, 54·2% during the second, 22·9% during the third, 8·4% during the fourth, and 4·8% during the fifth. Other studies have also reported that the period of risk for thrombosis persists beyond the first postoperative week.2, 3, 4, 5, 6 In addition, several studies have documented the rate of late-onset symptomatic thrombosis in THE patients with normal discharge venograms.7, 8, 9, 10, 11, 12 Seagroatt13 reported that DVT was the most common cause of readmission after THR.
By contrast, several studies have reported a low rate of venous thromboembolism among orthopaedic patients with normal discharge venograms.14, 15, 16 These studies led to the conclusion that orthopaedic patients can be discharged without the continuation of prophylaxis; an approach that is practised by many orthopaedic surgeons.17, 18 Others have recommended that prophylaxis be continued for different durations after discharge.19, 20, 21, 22, 23 In 1992, the European Consensus Statement identified prophylaxis after discharge from hospital as a key issue to be addressed by appropriately designed prospective trials.24
The aims of our prospective, randomised, double-blind, single-centre study were: to investigate the rate of delayed venous thromboembolic complications in patients who had undergone THR and did not have venogram-proven DVT at hospital discharge; and to assess the efficacy and safety of continuing low-molecular-weight heparin (LMWH) prophylaxis after discharge from hospital.
Section snippets
Methods
Consecutive hospital inpatients, older than 45 years of bodyweight 45–95 kg, who had undergone primary THR or conversion or revision THR surgery and were receiving LMWH prophylaxis for postoperative venous thromboembolism were considered for inclusion in our study. Eligible patients were those who were able to walk with crutches without assistance, and who did not have a diagnosis of DVT, as assessed by bilateral ascending contrast venography of the legs no more than 5 days before discharge. In
Results
Between August, 1991, and June, 1994, 532 consecutive patients scheduled for THR were screened for inclusion in our study. 353 patients did not meet the inclusion criteria: six were younger than 45 years; 43 weighed less than 45 kg or more than 95 kg; four had surgery more than 15 days before the first venogram could be done; four had had their enoxaparin prophylaxis interrupted for more than 1 day during their stay in hospital; eight were not able to attend the follow-up assessment on day 21;
Discussion
We believe that a placebo group was ethically justifiable because all patients received effective antithrombotic prophylaxis in hospital and were discharged 14 days after surgery with normal bilateral venograms. The rate of clinical suspicion of DVT after discharge was higher in our study than in previous reports,7, 8, 9, 10, 11, 12, 16, 20, 23 perhaps because of the systematic recording of symptoms and signs.
Most symptoms or signs of DVT affected the operated leg, which may explain why the
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