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Table 1 Summary of characteristics of two pre-existing reviews (Fagaranasu et al. 2016; Akl et al. 2008)

From: Extended versus inpatient thromboprophylaxis with heparins following major open abdominopelvic surgery for malignancy: a systematic review of efficacy and safety

 Fagaranasu et al. (SR1)Akl et al. (SR2)
TitleRole of extended thromboprophylaxis after abdominal and pelvic surgery in cancer patients: a systematic review and meta-analysisExtended perioperative thromboprophylaxis in patients with cancer, a systematic review
JournalAnn Surg OncolCellular proteolysis and oncology
FundingDid not comment“Institutional support” + one author funded by a European Commission
Time period includedInception of database—May 2015Did not comment
Databases searched- Cochrane Central Register of Controlled Trials
- Cochrane Register of Controlled Trials (Jan. 2007)
- ISI the Web of Science
MeSH terms used- Abdominal surgery
- Pelvic surgery
- Thromboprophylaxis
Not listed
Supplementary materials- Abstracts from hematology oncology conferences
- Clinical trial registries
- Manual search of reference lists
- Screening health technology assessments
- Hand searching of conference proceedings
- Review of reference lists
- Related article feature in PubMed
Population- Adult (> 18 years) patients receiving thromboprophylaxis with low molecular weight heparin after abdominal or pelvic cancer surgeryAdult patients with abdominal cancer undergoing abdominal surgery
Inclusion criteria- Randomized clinical trial or prospective observational cohort comparing extended thromboprophylaxis (2–6/52 postop) with conventional thromboprophylaxis (< 2/52 postop)
- Use of thromboprophylaxis with low molecular weight heparin
- All VTE outcomes objectively diagnosed using US/CTPA/VQ scan
- Included asymptomatic objectively diagnosed VTE
- Study reported at least one of DVT, PE, mortality, and major bleeding
- Adult (> 18) patients
- Randomized controlled trials assessing all-cause mortality, symptomatic DVT, pulmonary embolism, major bleeding, minor bleeding, injection site hematoma, and heparin induced thrombocytopenia
- Follow-up rate equal to or greater than 80% for the outcome under consideration
Quality assessment toolNewcastle-Ottawa scaleGRADE
Number of papers identified; included2763 papers identified
32 full text review
7 eligible included studies (3 randomized controlled trials, 4 observational)
3986 papers identified
3 eligible included studies
Outcomes-efficacy1) All VTE: extended thromboprophylaxis significantly reduced incidence of all VTE compared with conventional thromboprophylaxis (2.6% versus 5.6% risk ratio (RR) 0.44, confidence interval (CI) 0.28–0.70, number needed to treat (NNT) 39)
2) Proximal DVT: incidence significantly lower in extended thromboprophylaxis group (1.4% versus 2.8% CI 0.23–0.91, NNT 71)
3) Distal DVT: results did not reach statistical significance
4) PE: no statistically significant difference between PE incidence in the two groups
1) Symptomatic DVT: none had analyzable data
2) Asymptomatic DVT: only one study with sufficient follow-up rate—statistically significant difference at 4 weeks postop
3) PE: only reported in one study, insufficient follow-up rate for criteria
Outcomes-safety1) Major bleeding: no statistically significant difference observed
2) All-cause mortality: overall mortality similar 4.2% versus 3.6% RR 0.79, CI 0.47–1.33, NNT 167
1) All-cause mortality: only reported in one study, with no statistically significant difference at 3 or 12 months.
2) Bleeding: only reported in one study—no statistically significant difference at 4 weeks or 3 months postoperatively for either major or minor bleeding
ConclusionsExtended thromboprophylaxis significantly reduces the overall incidence of VTE and proximal DVT without increasing the risk of major bleeding.There is limited and low-quality evidence that extended duration of low molecular weight heparin for perioperative thromboprophylaxis reduces DVT in patients with cancer undergoing major abdominal or pelvic surgery.
More and better quality evidence is needed to justify extended regimens.
Acknowledged limitations of review- Only 3 randomized controlled trials identified
- Heterogeneity from inclusion of different types of surgeries, 3 studies allowed inclusion laparoscopic interventions
- Insufficient data on specific cancer types and stages; consequently, individualized recommendations cannot be derived from data
- Open label nature of some included studies; associated bias in patient symptom reporting and physician suspicion of VTE
- Restriction of electronic search strategy to patients with cancer (potential missed studies with subgroups of cancer patients)
- Limited number and low quality of included studies (included small sample size, high loss to follow up, focus on asymptomatic DVT)
Strengths of review- Comprehensive search
- Inclusion all major prospective studies to date assessing ETP after major abdominal and pelvic cancer surgery
- All VTE objectively diagnosed
- Outcomes between studies reasonably similar
- Low statistical heterogeneity
- Use of Cochrane collaboration methodology
- Priori definition of outcomes
- GRADE approach to evaluate quality of evidence