Postoperative versus preoperative initiation of deep-vein thrombosis prophylaxis with a low-molecular-weight heparin (Nadroparin) in elective hip replacement

The aim of this multicenter, randomized, double-blind study performed in patients undergoing elective hip surgery was to compare the efficacy and safety of prophylaxis with low-molecular-weight heparin (LMWH) (Nadroparin, 7,500 anti-Xa IC units for the first 3 days and 10,000 from the fourth day on, s.c. o.i.d.) begun in one group shortly after surgery and in the other 12 h before operation, as is usually recommended. Preoperative administration (drug or placebo) was the only difference between the two groups. Deep vein thrombosis (DVT) was detected by bilateral venography 10-15 days after surgery. The study investigated 179 patients (55 men), 40-80 years old, in seven Italian orthopedic centers. In 131 patients efficacy analysis was possible because of adequate bilateral venography. All 179 patients were evaluated for bleeding complications. The prevalence of thrombotic complications was similar in the two groups. Proximal DVT was found in 8.4% of patients (10.8% and 6.1% in the preop and postop groups, respectively; difference not statistically significant). Distal DVT was recorded in 30.5% of patients (30.8% and 30.3% in the pre- and postop groups, respectively). DVTs were more common in patients greater than or equal to 65 years old (54.2% versus 28.4%, p < 0.05); no significant differences were detected in terms of other characteristics. No significant differences were recorded in the number or type of bleeding complications: major (nonfatal) bleeding episodes were reported in five patients (2.8%, two and three in the pre- and postop groups); minor bleeding was noted in 25 (13.9%, 14 and 11 in the pre- and postop groups). In conclusion, the present study suggests that a LMWH regimen started postoperatively is no less effective in preventing DVT in elective hip replacement than the classical regimen started preoperatively. Surprisingly, postoperative commencement offered no significant advantage in terms of bleeding complications.