Abstract
The selection of venous thromboembolism (VTE) prophylaxis after total joint arthroplasty (TJA) has been controversial. Although the aspirin controversy is presumably resolved, there is no medical evidence for the “optimal” VTE prophylaxis regime for individual patients.
A risk-stratified multi-modal VTE prophylaxis protocol was developed and adopted by consensus. VTE risk factors and bleeding risk factors were categorised into six VTE/bleeding risk levels: (1) pre-operative vitamin K antagonists (VKA) use, (2) bleeding risk factors, (3) hypercoagulable state, (4) pre-operative anti-platelet therapy [clopidogrel use], (5) VTE risk factors, (6) no VTE or bleeding risk factors. The pharmacologic agents used for each risk level were: (1) resume VKA with low molecular weight heparin (LMWH) bridge, (2) pharmacologic agents contra-indicated and mechanical prophylaxis only, (3) VKA for 90 days with LMWH bridge, (4) resume anti-platelet therapy, (5) LMWH in hospital and discharge on aspirin for 90 days, (6) aspirin for 90 days (starting in hospital). In addition to pharmacologic treatment, all patients received multi-modal prophylaxis including early mobilisation, mechanical foot pumps, and neuraxial anesthesia when not contra-indicated. Prior to surgery, a VTE/bleeding risk factor checklist was completed determining the risk level. The intervention cohort included all TJA patients from January 1, 2010 to December 31, 2012. The comparison cohort included all TJA patients from the year prior to implementation of the protocol at the same community hospital. Thirty day all-cause non-elective re-admissions, 30 day same-site re-operations, 90 day VTE events, and protocol compliance were abstracted from the electronic medical record.
The intervention group consisted of 2679 patients (1075 hip arthroplasty patients and 1604 knee arthroplasty patients). The comparison group consisted of 1118 patients (323 hip arthroplasty patients and 795 knee arthroplasty patients). The 30 day all cause non-elective re-admission rate was 2.72% (73/2679) in the intervention group and 4.29% (48/1118) in the comparison group (p=0.0148). The 30 day same-site re-operation rate was 1.38% (37/2679) in the intervention group and 1.25% (14/1118) in the comparison group (p=0.8773). The 90 day VTE event rate was 1.57% (42/2679) in the intervention group and 3.40% (38/1118) in the comparison group (p=0.0007). The VTE rate was higher for knee arthroplasty patients 2.00% (32/1604) than for hip arthroplasty patients 0.93% (10/1075) (p=0.0379). The rate of VTE events was higher for patients that deviated from the VTE protocol 5.03% (10/199) than for all risk groups treated per the protocol 1.29% (32/2481) (p=0.0007).
The risk-stratified multi-modal VTE prophylaxis protocol simultaneously reduced 30 day all-cause non-elective re-admissions and 90 day VTE events. The possible causes for reducing 30 day re-admissions and reducing 90 day VTE events are: (1) reducing bleeding events by using aspirin for VTE prophylaxis in more than 80% of patients, (2) extending VTE prophylaxis to 90 days, and (3) using multi-modal prophylaxis. The risk-stratified multi-modal VTE prophylaxis protocol for total joint arthroplasty is consistent with 9 of the 10 recommendations in the AAOS Clinical Practice Guideline. The risk-stratification checklist provides a standardised tool to assess risks, discuss risks, and make shared decision with patients. Patient treatment that deviated from the protocol had a significantly higher VTE rate (5.03%). Protocol compliance increased each year from 91.1% in 2010 to 94.2% in 2012.
