Therapeutics
Risk-stratified vs routine antithrombotics for TKA: fewer wound complications without increasing DVT
Kulshrestha V, Kumar S. DVT prophylaxis after TKA: routine anticoagulation vs risk screening approach—a randomized study. J Arthroplasty. 2013;28:1868-73.
Clinical impact rating: H ★★★★★✩✩ Question
Conclusions
What is the relative effectiveness of risk-stratified and routine anticoagulation prophylaxis for symptomatic deep venous thrombosis (DVT) and wound complications after total knee arthroplasty (TKA)?
Prophylaxis using risk-stratified antithrombotic therapy reduced wound complications compared with routine antithrombotic therapy after total knee arthroplasty. The risk-based approach did not increase symptomatic DVT.
Methods
*Information provided by author.
Design: Randomized controlled trial (RCT).
†See Glossary.
Allocation: {Concealed}*.† Blinding: Blinded† (patients and outcome assessors).
Source of funding: No external funding.
Follow-up period: 1 year.
For correspondence: Dr. V. Kulshrestha, Army Hospital Research & Referral, Delhi Cantt, New Delhi, India. E-mail [email protected] ■
Setting: Multispecialty, tertiary care military hospital in India. Patients: 673 patients with knee osteoarthritis who had elective unilateral (n = 446) or staged bilateral (n = 227) TKAs; were not using anticoagulants; and were assessed for risk using a DVT scoring system based on age, past venous thromboembolism, family history of thrombosis or blood-clotting disorders, recent major surgery, comorbid conditions, and other risk factors (score ≤ 2 = standard risk, score > 2 = high risk). Exclusion criteria included contraindication to nonsteroidal antiinflammatory drugs. 900 knees (mean patient age 64 y) were randomized. Bilateral TKAs were done with a ≥ 3-month delay between knees. Intervention: Risk-stratified antithrombotic therapy using daily sham enoxaparin injections for 2 weeks plus oral aspirin for 4 weeks starting on the first postoperative day in patients at standard risk, and subcutaneous enoxaparin plus aspirin placebo for 2 weeks followed by aspirin for 2 weeks in patients at high risk (333 patients, 450 knees); or routine antithrombotic therapy in all patients, using enoxaparin, half dose at 8 hours after surgery and full dose for 2 weeks {plus aspirin placebo}* starting on the first postoperative day, followed by aspirin for 2 weeks (340 patients, 450 knees). Aspirin, 325 mg, was given twice daily, and the full dose of enoxaparin was 40 mg/d. Outcomes: Symptomatic DVT and wound complications. 900 knees were needed to detect a symptomatic DVT rate ≤ 7% in the risk-stratified anticoagulation group compared with 2% to 3% in the routine anticoagulation group (80% power, α1-sided = 0.05). Patient follow-up: 100%.
Main results 57% of TKAs in the risk-stratified group were rated as high risk for DVT. Risk-stratified and routine antithrombotic therapy did not differ for symptomatic DVT; risk-stratified antithrombotic therapy reduced wound complications (Table). Risk-stratified vs routine anticoagulation after total knee arthroplasty‡ Outcomes
Risk-stratified Routine RRI/RRR (95% CI) group group
NNT (CI)
Symptomatic DVT
2.4%
1.8%
RRI 38% (−43 to 229)
Not significant
Wound complications
4.4%
8.4%
RRR 47% (12 to 69)
25 (14 to 124)
‡DVT = deep venous thrombosis; other abbreviations defined in Glossary. Results are reported for knees rather than patients. RRI, RRR, NNT, and CI calculated from event rates reported in article.
17 December 2013 | ACP Journal Club | Volume 159 • Number 12
Commentary Recognizing that individual patients may differ in their predisposition to thrombosis, risk-stratified approaches to thromboprophylaxis have been developed for both medical and general surgical patients. However, risk-stratified thromboprophylaxis has not been widely used after major orthopedic surgery, in part because the thrombotic risk associated with the surgery is believed to dwarf the contribution of patient-related risk factors (1). Indeed, riskstratified thromboprophylaxis has not been recommended in this population (1, 2). The results of the study by Kulshrestha and Kumar challenge the prevailing wisdom and suggest that risk-stratified thromboprophylaxis may improve outcomes after TKA. The study used a rigorous design and measured clinically relevant outcomes. However, several limitations warrant mention. The study was done at a single center without centralized adjudication of outcomes and used an unvalidated risk-stratification tool. Patients received enoxaparin at a dose of 40 mg/d. Whether the results apply to the typical North American orthopedic surgery dose of 30 mg twice daily is unknown. Finally, several variables in the risk-stratification tool (e.g., diabetes mellitus, obesity, and smoking) have also been identified as risk factors for wound complications after TKA (3). Thus, many patients at highest risk for wound complications would not be eligible for aspirin prophylaxis using the authors’ tool. Notwithstanding these limitations, risk-stratified thromboprophylaxis after TKA deserves further study, ideally in a multicenter RCT that uses a psychometrically validated risk stratification tool derived using rigorous methods. Adam Cuker, MD, MS Perelman School of Medicine University of Pennsylvania Philadelphia, Pennsylvania, USA References 1. Falck-Ytter Y, Francis CW, Johanson NA, et al; American College of Chest Physicians. Prevention of VTE in orthopedic surgery patients: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2012;141:e278S-325S. 2. Mont MA, Jacobs JJ, Boggio LN, et al; AAOS. Preventing venous thromboembolic disease in patients undergoing elective hip and knee arthroplasty. J Am Acad Orthop Surg. 2011;19:768-76. 3. Vince K, Chivas D, Droll KP. Wound complications after total knee arthroplasty. J Arthroplasty. 2007;22:39-44.
© 2013 American College of Physicians
Downloaded From: http://annals.org/pdfaccess.ashx?url=/data/journals/aim/929454/ by a Fudan University User on 01/11/2017
JC5
Risk-stratified vs routine antithrombotics for TKA: fewer wound complications without increasing DVT
Kulshrestha V, Kumar S. DVT prophylaxis after TKA: routine anticoagulation vs risk screening approach—a randomized study. J Arthroplasty. 2013;28:1868-73.
Clinical impact rating: H ★★★★★✩✩ Question
Conclusions
What is the relative effectiveness of risk-stratified and routine anticoagulation prophylaxis for symptomatic deep venous thrombosis (DVT) and wound complications after total knee arthroplasty (TKA)?
Prophylaxis using risk-stratified antithrombotic therapy reduced wound complications compared with routine antithrombotic therapy after total knee arthroplasty. The risk-based approach did not increase symptomatic DVT.
Methods
*Information provided by author.
Design: Randomized controlled trial (RCT).
†See Glossary.
Allocation: {Concealed}*.† Blinding: Blinded† (patients and outcome assessors).
Source of funding: No external funding.
Follow-up period: 1 year.
For correspondence: Dr. V. Kulshrestha, Army Hospital Research & Referral, Delhi Cantt, New Delhi, India. E-mail [email protected] ■
Setting: Multispecialty, tertiary care military hospital in India. Patients: 673 patients with knee osteoarthritis who had elective unilateral (n = 446) or staged bilateral (n = 227) TKAs; were not using anticoagulants; and were assessed for risk using a DVT scoring system based on age, past venous thromboembolism, family history of thrombosis or blood-clotting disorders, recent major surgery, comorbid conditions, and other risk factors (score ≤ 2 = standard risk, score > 2 = high risk). Exclusion criteria included contraindication to nonsteroidal antiinflammatory drugs. 900 knees (mean patient age 64 y) were randomized. Bilateral TKAs were done with a ≥ 3-month delay between knees. Intervention: Risk-stratified antithrombotic therapy using daily sham enoxaparin injections for 2 weeks plus oral aspirin for 4 weeks starting on the first postoperative day in patients at standard risk, and subcutaneous enoxaparin plus aspirin placebo for 2 weeks followed by aspirin for 2 weeks in patients at high risk (333 patients, 450 knees); or routine antithrombotic therapy in all patients, using enoxaparin, half dose at 8 hours after surgery and full dose for 2 weeks {plus aspirin placebo}* starting on the first postoperative day, followed by aspirin for 2 weeks (340 patients, 450 knees). Aspirin, 325 mg, was given twice daily, and the full dose of enoxaparin was 40 mg/d. Outcomes: Symptomatic DVT and wound complications. 900 knees were needed to detect a symptomatic DVT rate ≤ 7% in the risk-stratified anticoagulation group compared with 2% to 3% in the routine anticoagulation group (80% power, α1-sided = 0.05). Patient follow-up: 100%.
Main results 57% of TKAs in the risk-stratified group were rated as high risk for DVT. Risk-stratified and routine antithrombotic therapy did not differ for symptomatic DVT; risk-stratified antithrombotic therapy reduced wound complications (Table). Risk-stratified vs routine anticoagulation after total knee arthroplasty‡ Outcomes
Risk-stratified Routine RRI/RRR (95% CI) group group
NNT (CI)
Symptomatic DVT
2.4%
1.8%
RRI 38% (−43 to 229)
Not significant
Wound complications
4.4%
8.4%
RRR 47% (12 to 69)
25 (14 to 124)
‡DVT = deep venous thrombosis; other abbreviations defined in Glossary. Results are reported for knees rather than patients. RRI, RRR, NNT, and CI calculated from event rates reported in article.
17 December 2013 | ACP Journal Club | Volume 159 • Number 12
Commentary Recognizing that individual patients may differ in their predisposition to thrombosis, risk-stratified approaches to thromboprophylaxis have been developed for both medical and general surgical patients. However, risk-stratified thromboprophylaxis has not been widely used after major orthopedic surgery, in part because the thrombotic risk associated with the surgery is believed to dwarf the contribution of patient-related risk factors (1). Indeed, riskstratified thromboprophylaxis has not been recommended in this population (1, 2). The results of the study by Kulshrestha and Kumar challenge the prevailing wisdom and suggest that risk-stratified thromboprophylaxis may improve outcomes after TKA. The study used a rigorous design and measured clinically relevant outcomes. However, several limitations warrant mention. The study was done at a single center without centralized adjudication of outcomes and used an unvalidated risk-stratification tool. Patients received enoxaparin at a dose of 40 mg/d. Whether the results apply to the typical North American orthopedic surgery dose of 30 mg twice daily is unknown. Finally, several variables in the risk-stratification tool (e.g., diabetes mellitus, obesity, and smoking) have also been identified as risk factors for wound complications after TKA (3). Thus, many patients at highest risk for wound complications would not be eligible for aspirin prophylaxis using the authors’ tool. Notwithstanding these limitations, risk-stratified thromboprophylaxis after TKA deserves further study, ideally in a multicenter RCT that uses a psychometrically validated risk stratification tool derived using rigorous methods. Adam Cuker, MD, MS Perelman School of Medicine University of Pennsylvania Philadelphia, Pennsylvania, USA References 1. Falck-Ytter Y, Francis CW, Johanson NA, et al; American College of Chest Physicians. Prevention of VTE in orthopedic surgery patients: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2012;141:e278S-325S. 2. Mont MA, Jacobs JJ, Boggio LN, et al; AAOS. Preventing venous thromboembolic disease in patients undergoing elective hip and knee arthroplasty. J Am Acad Orthop Surg. 2011;19:768-76. 3. Vince K, Chivas D, Droll KP. Wound complications after total knee arthroplasty. J Arthroplasty. 2007;22:39-44.
© 2013 American College of Physicians
Downloaded From: http://annals.org/pdfaccess.ashx?url=/data/journals/aim/929454/ by a Fudan University User on 01/11/2017
JC5
