Optimal duration of anticoagulant thromboprophylaxis in total hip arthroplasty: new evidence in 55,540 patients with osteoarthritis from the Nordic Arthroplasty Register Association (NARA) group

Advances and current research in primary thromboprophylaxis to prevent hospital-associated venous thromboembolism

Hospital-associated venous thromboembolism (VTE) is defined as any case of VTE occurring during hospital admission and for up to 90 days post discharge. It accounts for over 50% of all cases of VTE internationally; indeed, there are an estimated 10 million cases of hospital-associated VTE annually. Over the last decade, there has been increasing interest in improving VTE risk assessment and thromboprophylaxis. This review summarises all the recent and ongoing major research studies and future challenges in the different areas, including medical, surgical and obstetric patients, as well as special areas such as lower limb immobilisation. We include sections on both pharmacological and mechanical thromboprophylaxis.

Development and validation of a clinical prediction model for 90-day venous thromboembolism risk following total hip and total knee arthroplasty: a multinational study

BACKGROUND

The risk of venous thromboembolism (VTE) following total hip arthroplasty (THA) and total knee arthroplasty (TKA) is 1.0% to 1.5%, despite uniform thromboprophylaxis.

OBJECTIVES

To develop and validate a prediction model for 90-day VTE risk.

METHODS

A multinational cohort study was performed. For model development, records were used from the Oxford Royal College of General Practitioners Research and Surveillance Centre linked to Hospital Episode Statistics and Office of National Statistics UK routine data. For external validation, data were used from the Danish Hip and Knee Arthroplasty Registry, the National Patient Registry, and the National Prescription Registry. Binary multivariable logistic regression techniques were used for development.

RESULTS

In the UK data set, 64 032 THA/TKA procedures were performed and 1.4% developed VTE. The prediction model consisted of age, body mass index, sex, cystitis within 1 year before surgery, history of phlebitis, history of VTE, presence of varicose veins, presence of asthma, history of transient ischemic attack, history of myocardial infarction, presence of hypertension and THA or TKA. The area under the curve of the model was 0.65 (95% CI, 0.63-0.67). Furthermore, 36 169 procedures were performed in the Danish cohort, of whom 1.0% developed VTE. Here, the area under the curve was 0.64 (95% CI, 0.61-0.67). The calibration slope was 0.92 in the validation study and 1.00 in the development study.

CONCLUSION

This clinical prediction model for 90-day VTE risk following THA and TKA performed well in both development and validation data. This model can be used to estimate an individual's risk for VTE following THA/TKA.

Association between duration of anticoagulant thromboprophylaxis and revision rate in primary total hip arthroplasty: a Danish and Norwegian nationwide cohort study

BACKGROUND AND PURPOSE

There are concerns that bleeding following primary total hip arthroplasty (THA) contributes to prolonged wound drainage and prosthetic joint infection (PJI). We examined whether short (1-5 days), medium (6-14 days), and extended (≥ 15 days) duration of thromboprophylaxis is associated with the 5-year revision rate after THA due to osteoarthritis.

PATIENTS AND METHODS

We performed a cohort study based on data from hip arthroplasty and administrative registries in Denmark and Norway (2008-2014). The outcome was revision surgery due to PJI, aseptic loosening or any cause, and patient mortality. Adjusted cause-specific hazard ratios (HRs) were analyzed with Cox regression analyses.

RESULTS

Among 50,482 THA patients, 8,333 received short, 17,009 received medium, and 25,140 received extended thromboprophylaxis. The HRs for revision due to PJI within 5 years were 1.0 (95%CI 0.7-1.3) and 1.1 (CI 0.9-1.3) for short and extended vs. medium treatment, whereas HR for extended vs. medium prophylaxis was 1.5 (CI 1.2-2.0) within 3 months. The HRs for revision due to aseptic loosening within 5 years were 1.0 (CI 0.7-1.4) and 1.1 (CI 0.9-1.4) for short and extended vs. medium treatment. The HRs for any revision within 5 years were 0.9 (CI 0.8-1.1) and 0.9 (CI 0.8-1.0) for short and extended vs. medium treatment. Extended vs. medium prophylaxis was associated with a decreased 0-3 month mortality. The absolute differences at 5 years were ≤ 1%.

CONCLUSION

Our data suggests no association between duration of anticoagulant thromboprophylaxis and revision rate within 5 years of primary THA. The extended thromboprophylaxis might be associated with early increased revision rate due to PJI but also with lower mortality; however, the clinical relevance of this finding requires further research.

Preventing Venous Thromboembolism after elective total hip arthroplasty surgery - are the current guidelines appropriate? Venous thromboembolism prophylaxis in elective total hip arthroplasty surgery

INTRODUCTION

Venous Thromboembolism after elective Total Hip Arthroplasty surgery is a well-recognised complication, resulting in fatal pulmonary embolism, post thrombotic syndrome and recurrent thrombotic episodes. Guidelines developed by clinical organisations attempt to provide evidence-based recommendations to clinicians.

METHODS

This narrative review evaluated the current available literature in relation to the available guidelines, to evaluate whether the current major guidelines reflect the evidence base. All major clinical guidelines were collated through database searching, alongside the relevant clinical studies.

PRINCIPAL FINDINGS

The promotion of a multi-modal approach, combining mechanical and chemical prophylaxis, does appear to be well validated, with mechanical prophylaxis offering positive clinical effects with little negative clinical consequence. Within the current guidelines surrounding VTE prevention in the elective-THA patient, there does appear to be a lack of prescription in relation to risk stratification and adopting personalised approaches for specific patient subsets.

CONCLUSION

We suggest moving away from protocolisation of VTE prevention, given the evidence base is not fully developed to allow a 'one-size-fits-all' approach.

High risk of venous thromboembolism after orthopedic surgery in patients with thrombophilia

OBJECTIVE

This study aimed at evaluating the effect of thrombophilia on the risk of venous thromboembolism (VTE) in patients undergoing any type of orthopedic surgery.

BACKGROUND

Patients undergoing orthopedic surgery are at high risk for VTE. Although patients with thrombophilia have an increased risk of VTE, it is currently unclear whether there is a synergetic effect in patients with thrombophilia who undergo orthopedic surgery.

METHODS

Data from a large population-based case-control study (the Multiple Environmental and Genetic Assessment [MEGA] of risk factors for venous thrombosis study) were used. Odds ratios (ORs) with 95% confidence intervals (CIs), adjusted for age, sex, and body mass index (BMI) (ORadj) were calculated for patients undergoing any orthopedic intervention.

RESULTS

Of 4721 cases and 5638 controls, 263 cases and 94 controls underwent orthopedic surgery. Patients who had any orthopedic intervention in the year before the index date were at higher risk of VTE (ORadj 3.7; 95% CI, 2.9-4.8) than those who did not undergo any orthopedic surgery. There was an additionally increased risk in patients with factor V Leiden (OR 17.5, 95% CI, 4.1-73.6), non-O blood group (OR 11.2; 95% CI, 3.4-34.0), or elevated plasma levels of factor VIII (OR 18.6; 95% CI, 7.4-46.9) all relative to patients without these defects, not undergoing orthopedic surgery.

CONCLUSIONS

Patients with factor V Leiden, high levels of factor VIII, or blood group non-O were found to have a high risk of VTE after orthopedic surgery. Identification of these patients may enable individualized thromboprophylactic treatment to efficiently reduce VTE risk.

Similar early mortality risk after cemented compared with cementless total hip arthroplasty for primary osteoarthritis: data from 188,606 surgeries in the Nordic Arthroplasty Register Association database

Background and purpose - Current literature indicates no difference in 90-day mortality after cemented compared with cementless total hip arthroplasty (THA). However, previous studies are hampered by potential selection bias and suboptimal adjustment for comorbidity confounding. Therefore, we examined the comorbidity-adjusted mortality up to 90 days after cemented compared with cementless THA performed due to osteoarthritis.Patients and methods - Using the Nordic Arthroplasty Register Association database, 2005-2013, we included 108,572 cemented and 80,034 cementless THA due to osteoarthritis. We calculated the Charlson comorbidity index of each patient based on data from national patient registers. The Kaplan-Meier method was used to estimate unadjusted all-cause mortality. Cox regression was used to estimate hazard ratios (HR) with 95% confidence intervals (CI) for 14, 30-, and 90-day mortality comparing cemented with cementless THA, adjusting for age, sex, comorbidity, nation, and year of surgery.Results - Cumulative all-cause mortality within 90 days was 0.41% (CI 0.37-0.46) after cemented and 0.26% (CI 0.22-0.30) after cementless THA. The adjusted HR for cemented vs. cementless fixation was 0.97 (CI 0.79-1.2), and similar risk estimates were obtained for mortality within 14 (adjusted HR 0.91 [CI 0.64-1.3]) and 30 days (adjusted HR 0.94 [CI 0.71-1.3]). We found no clinically relevant differences in mortality between cemented and cementless THA in analyses stratified by age, sex, Charlson comorbidity index, or year of surgery.Interpretation - After adjustment for comorbidity as an important confounder, we observed similar early mortality between the 2 fixation techniques.

Preventing VTE following total hip and knee arthroplasty: Is prediction the future?

Venous thromboembolism (VTE) is a common complication following total hip arthroplasty (THA) and total knee arthroplasty (TKA). Many guidelines advise on the ideal pharmacological thromboprophylaxis strategy; however, despite its use, approximately 1.5% of patients still develop symptomatic VTE. Considering the large number of THAs and TKAs performed worldwide (2.5 million in total), the impact of VTE following these interventions is enormous. This paper discusses a concept how to further lower rates of VTE and bleeding complications following surgery. By stratifying patients according to their risk, we can optimize the balance between VTE and bleeding for each individual. This way, low-risk patients may be safely withheld from treatment (and avoid unnecessary bleeding complications and costs), whereas high-risk patients should receive adequate therapy (for instance, an increased thromboprophylaxis dosage and duration). An individualized strategy requires a well-functioning VTE prediction model following THA and TKA to help physicians to decide on optimal thromboprophylaxis therapy.