Aspirin mono-therapy continuation does not result in more bleeding after knee arthroplasty

Factors contributing to perioperative blood transfusion during total hip arthroplasty in patients continuing preoperative aspirin treatment: a nomogram prediction model

BACKGROUND

Total hip arthroplasty (THA) is associated with considerable blood loss during the perioperative period, which commonly requires a blood transfusion, especially in patients who continue aspirin treatment preoperatively. Blood transfusion can significantly increase both the length of hospital stay and total treatment costs and is potentially associated with adverse reactions. However, a visual predictive model for assessing the risk of blood transfusion in THA patients is lacking. The aim of this study was to develop and validate a nomogram to predict the risk of blood transfusion during THA in patients who continue aspirin treatment preoperatively.

METHODS

From June 2016 to December 2022, 228 consecutive patients who continued preoperative aspirin treatment and underwent primary unilateral THA were enrolled in this retrospective study. Potential risk factors were screened using least absolute shrinkage and selection operator (LASSO) regression, and univariate and multifactorial logistic regressions were performed on the factors screened using LASSO regression to further control for confounding effects. Finally, a nomogram was constructed on the basis of the variables identified through multiple regression analysis. Internal validation was carried out using the Bootstrap method to assess the performance of the model using the C-index, area under the receiver operating characteristic curve (AUC), calibration curve, and decision curve analysis (DCA).

RESULTS

Among the 228 patients, 43 (18.9%) received a blood transfusion. Patients who received a blood transfusion had a longer hospital stay (p = 0.01). The independent risk factors for blood transfusion included the concomitant use of clopidogrel (OR = 4.415), preoperative hemoglobin level (OR = 0.062), total estimated blood loss volume (OR = 3.411), American Society of Anesthesiologists (ASA) class (OR = 1.274), and the use of tranexamic acid (OR = 0.348). The prediction model had a C-index of 0.862, an internally validated C-index of 0.833, and an AUC of 0.833, indicating excellent discriminatory power. The calibration curve showed a good calibration effect, and DCA indicated that the nomogram has strong clinical applicability.

CONCLUSIONS

Based on these five independent risk factors, our nomogram can accurately predict the risk of blood transfusion in THA patients who continue aspirin treatment preoperatively, thereby assisting surgeons in clinical decision-making.

Impact of intra- and extramedullary alignment on blood loss in total knee arthroplasty: a retrospective study

BACKGROUND

There is a scarcity of scientific data regarding the correlation between alignment techniques during total knee arthroplasty (TKA) and blood loss as well as transfusion rates. This study's hypothesis posited that intramedullary-aligned (IM) TKA exhibits higher blood loss and transfusion rates when contrasted with extramedullary-aligned (EM) TKA.

METHODS

We conducted a retrospective examination of 883 patients who underwent total knee arthroplasty (TKA) in 2021 at a solitary orthopedic center in Germany. These patients were divided into two groups based on their tibial alignment technique: extramedullary alignment and intramedullary tibial alignment.

RESULTS

In the intramedullary tibial alignment (IM) group, we observed a blood loss of 0.91 L, while in the extramedullary tibial alignment (EM) group, the blood loss was 0.89 L. These values did not demonstrate a significant difference (p = 0.69). Transfusion rates were 0.99% in the IM group and 0.21% in the EM group, and there was no significant distinction between them (Chi-squared test: p > 0.05).

CONCLUSION

We observed no statistically significant variance in blood loss between the IM and EM groups. Likewise, there was no substantial disparity in transfusion rates between these groups. It can be concluded that the selection of a knee arthroplasty system incorporating either intramedullary tibial alignment or extramedullary alignment does not significantly impact blood loss.

Cemented and hybrid total hip arthroplasty lead to lower blood loss in primary total hip arthroplasty: a retrospective study

BACKGROUND

Little scientific evidence exists on blood loss and transfusion rates depending on the fixation technique. The hypothesis of this study was that the blood loss and transfusion rate are lower in cemented and hybrid total hip arthroplasty (THA) compared to cementless THA.

METHODS

We retrospectively compared a total of 1500 patients who received either cementless, cemented, hybrid or reverse hybrid THA. All patients underwent THA in 2021 at a single orthopedic center in Germany.

RESULTS

The lowest blood loss was found in patients who received a fully cemented THA (695 ± 74 ml). Hybrid THA with a cemented stem showed a blood loss of 845 ± 30 ml and reverse hybrid THA showed the highest blood loss with an average of 994 ± 74 ml. Cementless THA caused an average blood loss of 957 ± 16 ml. There was a significant difference between cementless THA, hybrid THA (cemented stem), and fully cemented THA (p < 0.05). Transfusion rates ranged from 1.3% (cementless THA) to 7.9% (cemented THA) between the groups with a transfusion rate of 2.5% overall.

CONCLUSION

We found significantly lower blood loss in cemented THA and hybrid THA compared to cementless THA. Although blood loss was lower in cemented and hybrid THA, this did not result in lower transfusion rates. This could be due to other confounders such as age, comorbidities, and preoperative anemia.

Tranexamic acid in pertrochanteric fractures: a retrospective analysis of perioperative outcomes after fixation with a proximal femoral nail

Background

Treatment of pertrochanteric femoral fractures is often associated with significant blood loss. It has already been demonstrated that the administration of tranexamic acid (TXA) for endoprosthetic procedures reduces blood losses and leads to a decreased frequency of postoperative complications. The aim of this study is to demonstrate whether the administration of TXA as part of osteosynthesis treatment for pertrochanteric fractures using a proximal femoral nail reduces perioperative blood losses and haemorrhage-related complications.

Methods

In a two-centre retrospective cohort study, 1 g TXA i.v. was administered preoperatively to 294 patients who had suffered from pertrochanteric femoral fractures. The subjects were compared clinically to a historical control group who did not receive TXA (nonTXA). Outcomes were evaluated on the basis of perioperative blood loss, transfusion requirement, and occurrence of complications.

Results

The TXA group showed evidence of a reduction in blood loss (TXA = 0.97 ± 0.47 l; nonTXA = 1.06 ± 0.47 l; p = 0.004) and a lower frequency of transfusion (TXA = 20%; nonTXA = 31%; p = 0.032) as compared to the nonTXA group. However, evidence of this therapeutic effect could only be demonstrated at one of the centres on subgroup comparison between the two centres. At the second centre, the data did not show a significant difference. A trend could be seen towards a reduction in postoperative renal failure. No complications occurred resulting from the administration of tranexamic acid.

Conclusion

Preoperative administration of TXA does not lead to an increased rate of thromboembolic complications when applied for treatment of pertrochanteric femoral fractures. Evidence of a positive effect could be seen in principle in relation to the reduction in perioperative blood loss and the frequency of transfusion. The difference in effect between the two centres remains to be clarified: for this reason, it is possible to assume that further factors influencing the efficacy of TXA administration are at play which were not taken into account in this study.

Preoperative Use of Aspirin in Total Knee Arthroplasty: Safe or Not?

OBJECTIVE

To compare the blood loss, transfusion rates and complications between the aspirin and non-aspirin group in unilateral and bilateral total knee arthroplasties (TKAs) with a nested case-control design.

METHODS

The present study retrospectively selected TKA cases from the Joint Arthroplasty Database at the Peking Union Medical College Hospital from January 2014 to December 2019 following strict inclusion and exclusion criteria, and divided them into the aspirin and non-aspirin group based on the use of aspirin preoperatively. Bleeding was measured by blood loss, transfusion rate, drainage volume, hemoglobin (HGB) and hematocrit (HCT), while complications (cardiovascular events, venous thromboembolism events, cerebrovascular events and wound events) were compared between the groups. Student's unpaired t-test and Mann-Whitney U-test were used to compare the differences of continuous variables between the two groups while chi-square test and Fisher's exact test were applied in categorical variables.

RESULTS

A total of 560 patients with unilateral TKA and 285 patients with bilateral TKA were extracted. Among these, 280 patients used aspirin preoperatively. No other differences were found in demographic and surgical characteristics between the two groups except for the proportion of coronary artery diseases (P < 0.001). For primary outcomes, there was no significant higher blood loss and transfusion rate in the aspirin group, while the drainage of aspirin group was higher than the control group in bilateral TKAs (P = 0.043). The HGB and HCT of the aspirin group was significant lower in both unilateral and bilateral TKAs at POD5 (P < 0.05). For complications, there was a lower vascular related complication rate in aspirin group after unilateral TKAs (P = 0.040), but the wound event rate in aspirin group was higher than the control group (P = 0.049).

CONCLUSIONS

Preoperative use of aspirin could prevent vascular related events during the perioperative period of TKA. However, it might also increase the risk of bleeding and wound complications.

The Risk of Bleeding and Adverse Events with Clopidogrel in Elective Hip and Knee Arthroplasty Patients

Orthopedic surgeons often face a clinical dilemma on how to manage antiplatelet therapies during the time of surgery. This retrospective study is aimed to investigate the bleeding risk and adverse events in patients who hold or keep clopidogrel during elective major joints arthroplasty. Two hundred and ninety-six patients that were treated with clopidogrel while undergoing total hip or knee joint replacement between January 2009 and December 2018 were studied. Group 1 included 56 patients (18.9%) who kept using clopidogrel preoperatively. Group 2 included 240 patients who hold clopidogrel use ≥5 days preoperatively. Blood transfusion rates, estimated blood loss, complication rates, and adverse cardiocerebral events were collected and analyzed. The mean total blood loss was more in the group 1 patients as compared with that in the group 2 patients (1212.3 mL (685.8 to 2811.8) vs. 1068.9 mL (495.6 to 3294.3), p = 0.03). However, there was no significant difference between the two groups of patients regarding transfusion rates, bleeding-related complications, and infection rates. There was a trend toward a higher incidence of adverse cardiocerebral events in patients withholding clopidogrel for more than 5 days before surgery. The results of this study suggest that clopidogrel continuation could be safe and advisable for patients at thrombotic risk undergoing primary major joint replacement. Acute antiplatelet withdrawal for an extended period of time might be associated with an increased risk of postoperative thromboembolic events. More studies are required in the future to further prove this suggestion.

Lower total blood loss in total knee arthroplasty with a low-pressure tourniquet than without

Tourniquet-use has been described in litera- ture as a surgical factor leading to increased post-operative hidden blood loss in total knee arthroplasty (TKA). The hypothesis for this retro- spective study was that low-pressure tourniquet TKA would offer the benefits of tourniquet surgery without the potential negative effects on late blood loss after the procedure. Therefore, this study evaluated total (TBL) and hidden blood loss (HBL) in TKA with or without a tourniquet. We retrospectively compared two groups : one group (n= 54) undergoing TKA without a tourniquet and one group with a low-pressure tourniquet (n= 110). The outcomes compared were hemoglobin levels 2 weeks before surgery and at days 2 and 4 after surgery to calculate total and hidden blood loss, transfusion rate, and functional outcome. A higher total blood loss was observed in the no tourniquet group with a mean loss of 1073 mL against 890 mL in the tourniquet group (p-value = 0,003). Hidden blood loss values between both groups were statistically not significant : in the no-tourniquet group, Hb drop between D2 and D4 was 0.5 g/dL against 0.4 g/ dL in the low-pressure tourniquet group. The tourniquet-less group did not present with better functional scores. This study showed that low- pressure tourniquet use reduces TBL without increasing HBL in TKA.

Effects of continuing use of aspirin on blood loss in patients who underwent unilateral total knee arthroplasty

PURPOSE

Concerning the ongoing debate on the effects of continuing aspirin therapy on blood loss in knee arthroplasty, we conducted a retrospective investigation to test the hypothesis that continuation of aspirin prior total knee arthroplasty (TKA) will not cause more blood loss.

METHODS

From a database of patients who underwent unilateral TKA between 2011 and 2016, we identified two groups: the aspirin group (patients continued aspirin during perioperative period) and the nonaspirin group (patients had no current or recent history of aspirin usage). We extracted and compared patient demographic information, comorbidity index, baseline serum hemoglobin (Hb), and creatinine level between the two groups. We also compared our primary outcomes, including the total blood loss, transfusion requirement, and length of hospitalization between the two groups. A multivariate logistic regression for analyzing the risk factors of requiring transfusion was performed.

RESULTS

We found that apart from preoperative serum creatinine level, there was no difference in the baseline Hb level, perioperative change in Hb, total blood loss, or length of hospitalization between the two groups. The percentage of transfusion utilization was also comparable between the two groups. Our regression analysis shows that the risk of requiring transfusion after TKA is not significantly associated with patients taking aspirin therapy before operation.

CONCLUSION

Patients who underwent TKA with continuation of low-dose aspirin did not result in more blood loss. Current blood loss management has provided sufficient reduction of blood loss to accommodate aspirin therapy perioperatively. We suggest that it is safe to continue aspirin prior to TKA.

Is continuation of anti-platelet treatment safe for elective total hip arthroplasty patients?

INTRODUCTION

Acetylsalicylic acid (aspirin) is a commonly prescribed medication, especially in the age group of individuals who undergo elective total hip arthroplasty (THA). Preoperative discontinuation of aspirin is believed to reduce intraoperative bleeding and other complications, but it may increase the risk of perioperative cardiovascular events. In this study we have sought to evaluate the safety of continuous aspirin treatment in patients undergoing elective THA.

MATERIALS AND METHODS

This is a retrospective analysis of a consecutive cohort who underwent elective THA in a tertiary medical center between 2011 and 2018. The cohort was divided into two groups-one that received continuous preoperative aspirin treatment and one that did not. Blood loss, peri- and postoperative complications, readmissions, and short- and long-term mortality were compared between groups.

RESULTS

Out of 757 consecutive patients (293 males, 464 females) who underwent elective primary THA, 552 were in the "non-aspirin" group and 205 were in the "aspirin" group and were not treated preoperative with other medication affecting hemostasis. Perioperative continuation of aspirin treatment did not significantly increase perioperative bleeding, as indicated by changes in hemoglobin levels (P = 0.72). There were no significant differences in short- and long-term mortality (P = 0.47 and P = 0.4, respectively) or other perioperative complications, such as readmission (P = 0.78), deep or superficial infection (P = 1 and P = 0.47, respectively), and cardiovascular events (none in both groups).

CONCLUSION

Peri-operative continuation of aspirin treatment in patients undergoing elective primary THA did not increase perioperative complications or mortality compared to the non-aspirin-treated patients. The protective effects of aspirin from postoperative thrombotic and cardiovascular events are well documented. The current findings dispute the need to preoperatively withhold aspirin treatment in patients undergoing elective primary THA.

Low-Dose Aspirin Is Adequate for Venous Thromboembolism Prevention Following Total Joint Arthroplasty: A Systematic Review

BACKGROUND

Patients undergoing total joint arthroplasty (TJA) are at risk of developing venous thromboembolism (VTE) without adequate prophylaxis. Since the American Academy of Orthopedic Surgeons issued guidelines in 2007 recommending aspirin 325 mg bis in die for 6 weeks, aspirin has been favored as the main VTE prophylaxis. However, the appropriate dose and duration of aspirin are not well-studied. This systematic review aims to identify any differences between high and low dose as well as duration for aspirin thromboprophylaxis after TJA as outlined by previous studies.

METHODS

A search was performed using Ovid MEDLINE, EMBASE, and PubMed, including articles up to July 2016. Studies were included if they contained at least 1 cohort that underwent TJA with aspirin as the sole chemoprophylaxis and reported either (1) symptomatic VTE or (2) secondary outcomes such as major bleeding or 90-day mortality.

RESULTS

Forty-five papers were included. There were no significant differences in symptomatic pulmonary embolism, symptomatic deep vein thrombosis, 90-day mortality, or major bleeding between patients receiving low-dose or high-dose aspirin. Patients treated with aspirin for <4 weeks had a higher risk of major bleeding (1.59%) vs patients treated for 4 weeks (0.15%), which may be attributed to premature cessation or differential reporting. Patients treated with aspirin for <4 weeks had a statistically higher 90-day mortality (1.95%) vs patients treated for 4 weeks (0.07%). There was no significant difference between incidence of pulmonary embolism or deep vein thrombosis and the durations of aspirin treatment.

CONCLUSION

This review suggests that low-dose aspirin is not inferior to high-dose aspirin for VTE thromboprophylaxis in TJA patients. Additionally, patients treated with aspirin for less than 4 weeks may have a higher risk of major bleeding and 90-day mortality compared to patients treated for a longer duration.

Preoperative Management of Antithrombotics in Arthroplasty

Antithrombotic therapy is common in the arthroplasty patient population; the preoperative management of chronic antithrombotic medications requires coordination among the medical team. It is estimated that approximately 250,000 or 10% of patients on chronic antithrombotic medication undergo treatment interruption for surgical procedures annually in North America. Although the description of postoperative anticoagulation management after arthroplasty is extensive, orthopaedic literature describing the preoperative management of antithrombotic therapy is lacking. The goal of this guideline is to provide practicing orthopaedic surgeons concise recommendations for the preoperative management of common contemporary antithrombotics in the setting of elective arthroplasty using evidence-based guidelines from other medical specialties. All arthroplasty procedures are considered high bleeding risk in accordance with collaborative AAOS and ACC guidelines. Orthopaedic surgeons should collaborate with their colleagues in cardiology, anesthesia, and other specialties when planning perioperative antithrombotic interruption, particularly in the case of medically complex patients such as those with known risk factors for bleeding and clotting disorders. Resumption of antithrombotic therapy after arthroplasty is beyond the scope of this discussion; this should be performed in accordance with cardiology and anesthesia recommendations.

Does continued aspirin mono-therapy lead to a higher bleeding risk after total knee arthroplasty?

BACKGROUND

Evidence about the risk of bleeding and thromboembolism because of aspirin mono-therapy in total knee arthroplasty (TKA) is scant. We wanted to validate the risks of bleeding and thromboembolism with continued aspirin mono-therapy in unilateral and simultaneous bilateral TKA.

METHODS

We enrolled a series of 1655 patients who underwent unilateral or simultaneous bilateral TKA between December 2010 and December 2012. Drainage amount, postoperative hemoglobin level, change in hemoglobin, calculated blood loss, incidence and the amount of blood transfused, and the proportion of thromboembolic events were compared between patients who were and patients who were not on continued aspirin mono-therapy.

RESULTS

Calculated blood loss (969.1 ± 324.9 vs. 904.0 ± 315.5 ml), transfusion amounts (1.3 ± 1.5 vs. 1.0 ± 1.3 IU), and percentage of transfused patients (53.0% vs. 40.2%) were higher in unilateral TKA patients on continued aspirin mono-therapy. Outcome parameters and the proportion of DVT between groups were not significantly different. One patient (0.3%) not on aspirin mono-therapy developed a pulmonary embolism, and two others (0.6%) had cerebrovascular events.

CONCLUSION

Despite the slightly higher risks of bleeding, continuing aspirin mono-therapy during TKA might be safe with low risks of perioperative cerebrovascular, cardiovascular, and venous thromboembolic events.

Aspirin for thromboprophylaxis in major orthopedic surgery: old drug, new tricks?

Major orthopedic surgery, mainly entailing hip fracture surgery, hip and knee arthroplasty, is associated with significant morbidity and mortality, which are especially attributable to the high risk of postoperative VTE. Such a considerable risk is mainly due to a procoagulant state sustained by several important mechanisms, including massive release of procoagulants from tissue and bone damage, blood vessel injury, reduced venous emptying, perioperative immobilization and cement polymerization, among others. The risk of VTE during and after major orthopedic surgery approximates 50-80% in patients with no thromboprophylaxis, and persists for up 3 to 6 months after surgery. The anticoagulant or antithrombotic armamentarium entails several anticoagulants such as heparin, coumarins, fondaparinux, and the recently developed DOACs inhibiting either activated factor Xa (i.e., rivaroxaban, apixaban, edoxaban) or thrombin (i.e., dabigatran), as well as aspirin, i.e., the oldest antiplatelet drug to be ever discovered and used in clinical practice. The current guidelines are not in complete agreement regarding the choice of the ideal thromboprophylaxis, since some consider aspirin, and some discourage it. Recent evidence seems to support the use of aspirin in selected situations and in selected protocols. Therefore, we believe that consideration should be made about increasing the use of this old but still effective drug for perioperative prophylaxis of VTE, especially in patients for whom the administration of DOACs may be challenging.

Venous Thromboembolism Prophylaxis After TKA: Aspirin, Warfarin, Enoxaparin, or Factor Xa Inhibitors?

BACKGROUND

There is considerable debate regarding the ideal agent for venous thromboembolism (VTE) prophylaxis after TKA. Numerous studies and meta-analyses have yet to provide a clear answer and often omit one or more of the commonly used agents such as aspirin, warfarin, enoxaparin, and factor Xa inhibitors.

QUESTIONS/PURPOSES

Using a large database analysis, we asked: (1) What are the differences in VTE incidence in primary TKA after administration of aspirin, warfarin, enoxaparin, or factor Xa inhibitors? (2) What are the differences in bleeding risk among these four agents? (3) How has use of these agents changed with time?

METHODS

We queried a combined Humana and Medicare database between 2007 and Quarter 1 of 2016, and identified all primary TKAs performed using ICD-9 and Current Procedural Terminology codes. All patients who had any form of antiplatelet or anticoagulation prescribed within 1 year before TKA were excluded from our study cohort. We then identified patients who had either aspirin, warfarin, enoxaparin, or factor Xa inhibitors prescribed within 2 weeks of primary TKA. Each cohort was matched by age and sex. Elixhauser comorbidities and Charlson Comorbidity Index for each group were calculated. We identified 1016 patients with aspirin, and age- and sex-matched 6096 patients with enoxaparin, 6096 patients with warfarin, and 5080 patients with factor Xa inhibitors. Using ICD-9 codes, with the understanding that patients at greater risk may have had more-attentive surveillance, the incidence of postoperative deep venous thrombosis (DVT), pulmonary embolism (PE), bleeding-related complications (bleeding requiring surgical intervention, hemorrhage, hematoma, hemarthrosis), postoperative anemia, and transfusion were identified at 2 weeks, 30 days, 6 weeks, and 90 days postoperatively. A four-way chi-squared test was used to determine statistical significance. Utilization was calculated using compound annual growth rate.

RESULTS

There was a difference in the incidence of DVT at 90 days (p < 0.01). Factor Xa inhibitors (2.9%) had the lowest incidence of DVT followed by aspirin (3.0%) and enoxaparin (3.5%), and warfarin (4.8%). There was a difference in the incidence of PE at 90 days (p < 0.01). Factor Xa inhibitors (0.9%) had the lowest incidence of PE followed by enoxaparin (1.1%), aspirin (1.2%), and warfarin (1.6%). There was a difference in the incidence of postoperative anemia at 90 days (p < 0.01). Aspirin (19%) had the lowest incidence of postoperative anemia followed by warfarin (22%), enoxaparin (23%), and factor Xa inhibitors (23%). There was a difference in the incidence of a blood transfusion at 90 days (p < 0.01). Aspirin (7%) had the lowest incidence of a blood transfusion followed by factor Xa inhibitors (9%), warfarin (12%), and enoxaparin (13%). There were no differences in bleeding-related complications (p = 0.81) between the groups. Aspirin use increased at a compound annual growth rate of 30%, enoxaparin at 3%, and factor Xa inhibitors at 43%, while warfarin use decreased at a compound annual growth rate of -3%.

CONCLUSIONS

Factor Xa inhibitors had the highest growth in utilization during our study period, followed by aspirin, when compared with enoxaparin and warfarin. When selected for the right patient, factor Xa inhibitors provided improved VTE prophylaxis compared with enoxaparin and warfarin, with a lower rate of blood transfusion. Aspirin provided comparable VTE prophylaxis compared with factor Xa inhibitors with improved VTE prophylaxis compared with enoxaparin and warfarin with the lowest risk of bleeding.

LEVEL OF EVIDENCE

Level III, therapeutic study.

[Joint replacement in the elderly]

Special characteristics must be taken into consideration for replacement arthroplasty in the elderly. The indications, preoperative preparation, postoperative care, implant selection, intraoperative technique, as well as clinical results reveal sometimes substantial differences compared to younger patients. Based on these findings it is important to individualize the approach to patient therapy, especially due to distinct differences between chronological and biological age in the elderly, in association with the level of activity and expectations on the new joint. All types of implants, each with implant-specific characteristics that must be taken into consideration, are available independent of the age of the patient. In summary, attributes such as stability and pain-free mobility have to be given priority in the elderly.

Preoperative haemoglobin cut-off values for the prediction of post-operative transfusion in total knee arthroplasty

PURPOSE

The purpose of this study is to determine preoperative haemoglobin cut-off values that could accurately predict post-operative transfusion outcome in patients undergoing primary unilateral total knee arthroplasty (TKA). This will allow surgeons to provide selective preoperative type and screen to only patients at high risk of transfusion.

METHODS

A total of 1457 patients diagnosed with osteoarthritis and underwent primary unilateral TKA between January 2012 and December 2014 were retrospectively reviewed. Logistic regression analyses were applied to identify factors that could predict transfusion outcome.

RESULTS

A total of 37 patients (2.5 %) were transfused postoperatively. Univariate analysis revealed preoperative haemoglobin (p < 0.001), age (p < 0.001), preoperative haematocrit (p < 0.001), and preoperative creatinine (p < 0.001) to be significant predictors. In the multivariate analysis with patients dichotomised at 70 years of age, preoperative haemoglobin remained significant with adjusted odds ratio of 0.33. Receiver operating characteristic curve identified the preoperative haemoglobin cut-off values to be 12.4 g/dL (AUC = 0.86, sensitivity = 87.5 %, specificity = 77.2 %) and 12.1 g/dL (AUC = 0.85, sensitivity = 69.2 %, specificity = 87.1 %) for age above and below 70, respectively.

CONCLUSIONS

The authors recommend preoperative haemoglobin cut-off values of 12.4 g/dL for age above 70 and 12.1 g/dL for age below 70 to be used to predict post-operative transfusion requirements in TKA. To maximise the utilisation of blood resources, the authors recommend that only patients with haemoglobin level below the cut-off should receive routine preoperative type and screen before TKA.

LEVEL OF EVIDENCE

IV.