Prolonged Thromboprophylaxis with LMWH after Abdominal or Pelvic Surgery

Cochrane update: Prolonged Thromboprophylaxis with low-molecular-weight heparin beneficial after Abdominal or Pelvic surgery

Update shows a trend towards reduced symptomatic venous thromboembolism with extended thromboprophylaxis.

Key Takeaway

• Prolonged thromboprophylaxis (≥14 days) with low-molecular-weight heparin (LMWH) vs inpatient-only prophylaxis after major pelvic or abdominal surgery is associated with a reduction in all venous thromboembolism (VTE), all deep vein thrombosis (DVT) and proximal DVT outcomes.

• A trend towards reduced symptomatic VTE was observed with prolonged thromboprophylaxis with LMWH.

• Incidence of overall bleeding and mortality was not different between the LMWH and control groups.

Why This Matters

• Previous evidence suggests the risk of developing blood clots in weeks to months after surgery, even after a patient is considered safe for discharge from the hospital.

• Although some guidelines recommend, not all physicians recommend a prolonged course of blood thinner injections for a postoperative patient after discharge.

• Adoption of extended VTE prophylaxis is slow which necessitates updates to the evidence. Reassessing current evidence might increase adoption of extended VTE prophylaxis.

Study Design

• This Cochrane review evaluated 7 randomised controlled trials (n=1728 participants) that compared prolonged thromboprophylaxis with LMWH vs placebo or control in patients undergoing abdominal or pelvic surgery for both benign and malignant pathology.

• Primary outcomes: incidence of VTE (both symptomatic and asymptomatic VTE and pulmonary embolism) within 30 days of surgery.

• Secondary outcome: incidence of all DVT, proximal DVT, symptomatic VTE, bleeding complications and mortality within three months after surgery.

• Funding: None disclosed.

Key Results

• VTE incidence after major abdominal or pelvic surgery in patients receiving out-of-hospital LMWH was 5.3% vs 13.2% in the control group (Mantel Haentzel [M-H] OR, 0.38; 95% CI, 0.26-0.54; I²=28%).
• Incidence of all DVT (5.3% vs 12.9%; M-H OR, 0.39 [95% CI, 0.27-0.55]; I²=28%) and proximal DVT (0.8% vs 3.9%; M-H OR, 0.22 [95% CI, 0.10-0.47]; I²=0%) was lower in LMWH prophylaxis than those in control groups.
• A trend towards reduced symptomatic VTE was observed with prolonged thromboprophylaxis with LMWH vs control group (0.1% vs 1.3%; M-H OR, 0.30 [95% CI, 0.08-1.11]; I²=0%).
• No significant difference observed between LMWH prophylaxis and control arms in the incidence of:
  • overall bleeding (3.4% vs 2.8%; M-H OR, 1.10 [95% CI, 0.67-1.81]; I²=0%) and
  • mortality (3.9% vs 3.8%; M-H OR, 1.15 [95% CI, 0.72-1.84]; I²=0%).
• Quality of the evidence for all the above findings was moderate.

Limitations

• Included trials had 'surrogate' endpoints based on objective diagnosis carried out at extended time intervals after surgery.

• All included trials had high attrition rates.