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Introduction: Pharmacologic prophylaxis (PP) against venous thromboembolism (VTE) is often withheld after hepatectomy due to bleeding risk or perceived coagulopathy related to INR and platelet count, but its role has been inadequately studied. We sought to characterize VTE risk and define the role of PP after hepatectomy.
Methods: Prospectively collected clinicopathologic and perioperative data on adult patients undergoing liver resection between 1/1/2003-7/31/2011 were retrospectively reviewed to assess incidence of and risk factors for postoperative VTE within 30 days. Risk factors for PP were analyzed using multivariable logistic regression.
Results: Of 2198 patients undergoing hepatectomy, median age was 60 years, and 49% were female. Median BMI was 27, preoperative chemotherapy was given to 997 patients (45%), and a history of prior VTE was present in 67 patients (3%). Major hepatectomy (MH, defined as ≥4 segments) was performed in 716 patients (33%) and another concomitant organ resection in 556 (25%). EBL was ≥600cc in 580 patients (27%), and liver steatosis was noted in 142 (18%). Median peak INR within 7 days after surgery was 1.4 (peak INR ≥1.5 in 32%), and median platelet count nadir was 154k (platelet nadir <100k in 12%). PP was started on day 0/1 (immediate) in 815 patients (37%), day 2-5 (early) in 481 (22%), and later or never (late/none) in 902 (41%). Use of any (immediate or early) PP was less common with MH (50% vs 63%, P<0.001), EBL≥600cc (54% vs 61%, P=0.002), and peak INR≥1.5 (54% vs 62%, P=0.001). VTE occurred in 57 patients (overall: 2.6%; immediate: 2.2%; early: 1.9%; late/none: 3.3%; P=0.2). VTE was associated with age ≥60 (3.9% vs 1.3%, P<0.001), MH (4.2% vs 1.8%, P=0.001), EBL≥600cc (4.8% vs 1.7%, P<0.001), and peak INR≥1.5 (5.2% vs 1.5%, P<0.001), but not gender, BMI, preoperative chemotherapy, history of VTE, other organ resection, liver steatosis, or nadir platelet count <100k (all P>0.05). There was no significant time trend in VTE incidence. On multivariable analysis, age, EBL, and peak INR remained significant predictors of VTE (Table).
Conclusions: Counterintuitively, higher INR, but not use of postoperative PP, was associated with VTE within 30 days after hepatectomy. INR alone may not be an accurate indicator of coagulation status after hepatectomy. The role of PP after hepatectomy requires prospective validation.
Multivariable Logistic Regression Analysis of Risk Factors for VTE

Variable	Odds Ratio	95% CI	P-Value
Age ≥60 years	3.06	1.65 - 5.70	0.001
Pharmacologic prophylaxis
Late/None	Ref.		0.4
Early (Day 2-5)	0.63	0.29 - 1.35
Immediate (Day 0/1)	0.78	0.42 - 1.45
Major hepatectomy	1.19	0.63 - 2.22	0.6
EBL ≥600 cc	2.09	1.18 - 3.69	0.01
Peak INR ≥1.5	3.03	1.58 - 5.79	0.001

Ref.: Referent