Background: VTE is a serious, but decreasing complication following major orthopedic surgery. This guideline focuses on optimal prophylaxis to reduce postoperative pulmonary embolism and DVT. Methods: The methods of this guideline follow those described in Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines in this supplement. Results: In patients undergoing major orthopedic surgery, we recommend the use of one of the following rather than no antithrombotic prophylaxis: low-molecular-weight heparin; fondaparinux; dabigatran, apixaban, rivaroxaban (total hip arthroplasty or total knee arthroplasty but not hip fracture surgery); low-dose unfractionated heparin; adjusted-dose vitamin K antagonist; aspirin (all Grade 1B); or an intermittent pneumatic compression device (IPCD) (Grade 1C) for a minimum of 10 to 14 days. We suggest the use of low-molecular-weight heparin in preference to the other agents we have recommended as alternatives (Grade 2C/2B), and in patients receiving pharmacologic prophylaxis, we suggest adding an IPCD during the hospital stay (Grade 2C). We suggest extending thromboprophylaxis for up to 35 days (Grade 2B). In patients at increased bleeding risk, we suggest an IPCD or no prophylaxis (Grade 2C). In patients who decline injections, we recommend using apixaban or dabigatran (all Grade 1B). We suggest against using inferior vena cava fi lter placement for primary prevention in patients with contraindications to both pharmacologic and mechanical thromboprophylaxis (Grade 2C). We recommend against Doppler (or duplex) ultrasonography screening before hospital discharge (Grade 1B). For patients with isolated lowerextremity injuries requiring leg immobilization, we suggest no thromboprophylaxis (Grade 2B). For patients undergoing knee arthroscopy without a history of VTE, we suggest no thromboprophylaxis (Grade 2B). Conclusions: Optimal strategies for thromboprophylaxis after major orthopedic surgery include pharmacologic and mechanical approaches. CHEST 2012; 141(2)(Suppl):e278S-e325SAbbreviations: DUS 5 Doppler (or duplex) ultrasonography; GCS 5 graduated compression stockings; HFS 5 hip fracture surgery; INR 5 international normalized ratio; IPCD 5 intermittent pneumatic compression device; IVC 5 inferior vena cava; LDUH 5 low-dose unfractionated heparin; LMWH 5 low-molecular-weight heparin; PE 5 pulmonary embolism; PEP 5 Pulmonary Embolism Prevention trial; RCT 5 randomized controlled trial; RR 5 risk ratio; THA 5 total hip arthroplasty; TKA 5 total knee arthroplasty; UFH 5 unfractionated heparin; VFP 5 venous foot pump; VKA 5 vitamin K antagonist

The physician's estimate of the probability that a patient has a particular disease is a principal factor in the determination of whether to withhold treatment, obtain more data by testing, or treat without subjecting the patient to the risks of further diagnostic tests. Using the concepts of decision analysis, we have derived expressions for two threshold probabilities involved in this choice: a "testing" threshold and a "test-treatment" threshold. Values can be assigned to these thresholds from data on the reliability and potential risks of the diagnostic test and the benefits and risks of a specific treatment. Treatment should be withheld if the probability of disease is smaller than the testing threshold, and treatment should be given without further testing if the probability of disease is greater than the test-treatment threshold. The test should be performed (with treatment depending on the test outcome) only if the probability of disease is between the two thresholds. The method exposes important principles of decision making and helps the clinician develop a rational, quantitative approach to the use of diagnostic tests.

We investigated how variations in the way information is presented to patients influence their choices between alternative therapies. Data were presented summarizing the results of surgery and radiation therapy for lung cancer to 238 ambulatory patients with different chronic medical conditions and to 491 graduate students and 424 physicians. We asked the subjects to imagine that they had lung cancer and to choose between the two therapies on the basis of both cumulative probabilities and life-expectancy data. Different groups of respondents received input data that differed only in whether or not the treatments were identified and whether the outcomes were framed in terms of the probability of living or the probability of dying. In all three populations, the attractiveness of surgery, relative to radiation therapy, was substantially greater when the treatments were identified rather than unidentified, when the information consisted of life expectancy rather than cumulative probability, and when the problem was framed in terms of the probability of living rather than in terms of the probability of dying. We suggest that an awareness of these effects among physicians and patients could help reduce bias and improve the quality of medical decision making.

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