Incidence and risk factors for symptomatic venous thromboembolism following cholecystectomy

Postoperative Timing of Chemoprophylaxis and Its Impact on Thromboembolism and Bleeding Following Major Abdominal Surgery: A Multicenter Cohort Study

BACKGROUND

Major abdominal surgery is associated with bleeding and venous thromboembolism (VTE) risks. Chemoprophylaxis prevents VTE but increases bleeding risk. When compared with pre- and intra-operative chemoprophylaxis, recent evidence suggests that starting chemoprophylaxis postoperatively lowers the risk of bleeding without compromising VTE protection. This study investigates whether an optimal window exists in the postoperative period for initiating chemoprophylaxis in patients undergoing major abdominal surgery.

METHODS

Analysis of pooled data from four multicenter PROTECTinG studies, which investigated the timing of perioperative chemoprophylaxis on bleeding and VTE outcomes following major abdominal surgery. Patients that commenced chemoprophylaxis postoperatively were separated into quartiles based on timing of administration within the first 24 h post-surgery.

RESULTS

Overall, 4729 (Abdominal visceral resection N = 668, cholecystectomies N = 573, major ventral hernia repair N = 1701, antireflux surgery N = 1787) consecutive patients had chemoprophylaxis commenced within 24 h following elective surgery. Baseline characteristics were comparable between quartiles. Across quartiles and within each procedural type, the timing of starting chemoprophylaxis was not associated with bleeding (2.6, 1.7, 2.7 and 3.2%, p = 0.130) or clinical VTE (0.8, 0.2, 0.8 and 0.5%, p = 0.131), and did not predict their occurrences on multivariate analysis.

CONCLUSION

Chemoprophylaxis can be safely started at any time within 24 h post-skin closure in major abdominal surgery, without affecting bleeding or VTE risks. This finding encourages the standardization of chemoprophylaxis timing in the postoperative period to pre-defined times during the day to improve workflow efficiency and chemoprophylaxis compliance.

A modeling approach to derive baseline risk estimates for GRADE recommendations:Concepts, development, and results of its application to the American Society of Hematology 2019 guidelines on prevention of venous thromboembolism in surgical hospitalized patients

OBJECTIVE

The goal of this study was to develop an approach that can be used where baseline risk estimates that are directly applicable to prioritized patient-important outcomes are not available from published studies.

STUDY DESIGN

The McMaster University GRADE Centre and the ASH guideline panel for the prevention of VTE in surgical patients developed a modeling approach based on explicit assumptions about the distribution of symptoms, anatomical location, and severity of VTE events.

RESULTS

We applied the approach to derive modeled estimates of baseline risk. These estimates were used to calculated absolute measures of anticipated effects that informed the discussion of the evidence and the formulation of 30 guideline recommendations.

CONCLUSIONS

Our approach can assist guideline developers facing a lack of information about baseline risk estimates that directly apply to outcomes of interest. The use of modeled estimates increases transparency in the process and makes the baseline risk used by guideline experts explicit during their decision-making.

American Society of Hematology 2019 guidelines for management of venous thromboembolism: prevention of venous thromboembolism in surgical hospitalized patients

BACKGROUND

Venous thromboembolism (VTE) is a common source of perioperative morbidity and mortality.

OBJECTIVE

These evidence-based guidelines from the American Society of Hematology (ASH) intend to support decision making about preventing VTE in patients undergoing surgery.

METHODS

ASH formed a multidisciplinary guideline panel balanced to minimize bias from conflicts of interest. The McMaster University GRADE Centre supported the guideline-development process, including performing systematic reviews. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess evidence and make recommendations, which were subject to public comment.

RESULTS

The panel agreed on 30 recommendations, including for major surgery in general (n = 8), orthopedic surgery (n = 7), major general surgery (n = 3), major neurosurgical procedures (n = 2), urological surgery (n = 4), cardiac surgery and major vascular surgery (n = 2), major trauma (n = 2), and major gynecological surgery (n = 2).

CONCLUSIONS

For patients undergoing major surgery in general, the panel made conditional recommendations for mechanical prophylaxis over no prophylaxis, for pneumatic compression prophylaxis over graduated compression stockings, and against inferior vena cava filters. In patients undergoing total hip or total knee arthroplasty, conditional recommendations included using either aspirin or anticoagulants, as well as for a direct oral anticoagulant over low-molecular-weight heparin (LMWH). For major general surgery, the panel suggested pharmacological prophylaxis over no prophylaxis, using LMWH or unfractionated heparin. For major neurosurgery, transurethral resection of the prostate, or radical prostatectomy, the panel suggested against pharmacological prophylaxis. For major trauma surgery or major gynecological surgery, the panel suggested pharmacological prophylaxis over no prophylaxis.