Caprini JA, Arcelus JI, Motykie G, Kudrna JC, Mokhtee D, Reyna JJ.
The influence of oral anticoagulation therapy on deep vein thrombosis rates four
weeks after total hip replacement.
J Vasc Surg 1999 Nov;30(5):813-20

Department of Surgery, Evanston Northwestern Healthcare, Evanston, Illinois, USA.

PURPOSE: The purpose of this study was to assess the rate of postoperative deep
vein thrombosis (DVT) as a function of oral anticoagulation therapy after total
hip replacement surgery. METHODS: A total of 125 patients completed the study.
All the patients received sequential gradient pneumatic compression over elastic
stockings until hospital discharge. In addition, all the patients underwent
postoperative heparin therapy followed by oral warfarin therapy, adjusted in dose
to maintain a goal international normalized ratio (INR) level of 2.0 to 3.0.
Warfarin therapy and compression stockings were continued for 1 month after
surgery. Bilateral duplex scanning was performed 1 and 4 weeks after surgery to
assess the rate of DVT. RESULTS: Nineteen of the 125 patients had DVT develop
(15.2%). Of those thromboses, six (31.6%) and 13 (68%) were detected 1 week and 1
month after surgery, respectively. The rate of proximal DVT was 2.4% (3 of 125) 1
week after surgery and rose to 8.2% (10 of 122) 1 month after surgery. Most DVT
cases (64%; 12 of 19) were asymptomatic. The patients in whom DVT developed had
significantly lower INR values during the second to fourth postoperative weeks
than did those patients without thrombosis, and no differences in INR values were
found during the first postoperative week. CONCLUSION: The risk of the
development of DVT extends beyond hospital discharge in patients who undergo
total hip replacement, despite a regimen of prolonged oral anticoagulation
therapy. This is particularly true in patients whose INR values did not reach
therapeutic range during the first postoperative month. Therefore, thrombosis
prophylaxis regimens on the basis of the administration of warfarin should try to
maintain INR values within therapeutic range during the entire first
postoperative month to minimize the incidence of DVT.