Orthopedics

Feature Article 

Effect of Acetylsalicylic Acid Dose and Time Discontinued Preoperatively on Outcomes After Total Knee and Hip Arthroplasty

Jonathan H. Shaw, MD; Omar M. Kadri, MD; Clifford M. Les, DVM, PhD; Michael Charters, MD

Abstract

The purpose of this study was to determine if acetylsalicylic acid (ASA) dose or time discontinued preoperatively affected surgical outcomes in total joint arthroplasty (TJA). The authors hypothesized that ASA worsens surgical outcomes in patients receiving higher doses and in those who discontinue ASA closer to the operative date. A total of 2853 TJAs (1802 primary total knee arthroplasties and 1051 total hip arthroplasties) performed at a tertiary medical center were reviewed. Postoperative outcomes of patients receiving ASA prior to TJA, dosing of ASA (81 mg or 325 mg) preoperatively and postoperatively, and the time of preoperative discontinuation (no ASA, <4 days, <7 days, and 7 or more days) were compared. Preoperative ASA was a risk factor for readmission (odds ratio [OR], 1.86; P<.001) and 90-day postoperative events (OR, 1.26; P=.004). Among patients receiving ASA, the dose was not a risk factor for any of the studied outcomes. Discontinuing ASA 7 or more days prior to TJA was protective for hematomas (OR, 0.64; P=.038), emergency department visits (OR, 0.79; P=.006), readmission (OR, 0.65; P<.001), and 90-day postoperative events (OR, 0.72; P<.001). These outcomes had a time effect: the risk was greater for those who discontinued therapy closer to the operative date. Patients who discontinued ASA 7 or more days prior to TJA had a lower incidence of hematomas, emergency department visits, readmissions, and 90-day postoperative events. This study's findings support discontinuing ASA at least 7 days prior to TJA. [Orthopedics. 2019; 42(5):286–293]

Abstract

The purpose of this study was to determine if acetylsalicylic acid (ASA) dose or time discontinued preoperatively affected surgical outcomes in total joint arthroplasty (TJA). The authors hypothesized that ASA worsens surgical outcomes in patients receiving higher doses and in those who discontinue ASA closer to the operative date. A total of 2853 TJAs (1802 primary total knee arthroplasties and 1051 total hip arthroplasties) performed at a tertiary medical center were reviewed. Postoperative outcomes of patients receiving ASA prior to TJA, dosing of ASA (81 mg or 325 mg) preoperatively and postoperatively, and the time of preoperative discontinuation (no ASA, <4 days, <7 days, and 7 or more days) were compared. Preoperative ASA was a risk factor for readmission (odds ratio [OR], 1.86; P<.001) and 90-day postoperative events (OR, 1.26; P=.004). Among patients receiving ASA, the dose was not a risk factor for any of the studied outcomes. Discontinuing ASA 7 or more days prior to TJA was protective for hematomas (OR, 0.64; P=.038), emergency department visits (OR, 0.79; P=.006), readmission (OR, 0.65; P<.001), and 90-day postoperative events (OR, 0.72; P<.001). These outcomes had a time effect: the risk was greater for those who discontinued therapy closer to the operative date. Patients who discontinued ASA 7 or more days prior to TJA had a lower incidence of hematomas, emergency department visits, readmissions, and 90-day postoperative events. This study's findings support discontinuing ASA at least 7 days prior to TJA. [Orthopedics. 2019; 42(5):286–293]

The medical optimization of patients prior to elective joint replacement is intricate and important for minimizing perioperative complications. Patients undergoing total joint arthroplasty (TJA) have many significant comorbidities. An increasing number of patients at the authors' center referred for TJA are taking acetylsalicylic acid (ASA) indicated for primary and secondary prevention of coronary artery disease. Many surgeons opt to discontinue ASA preoperatively to prevent intraoperative blood loss and postoperative bleeding complications, but this may increase the risk of complications in patients with recent cardiac stent placement.1–3

Currently, the American Academy of Orthopaedic Surgeons recommends suspending ASA 5 to 7 days prior to surgery for low-risk patients. These recommendations are thought to decrease the risk of intraoperative bleeding, postoperative blood loss, and reoperation due to bleeding.4,5 However, these recommendations are mostly based on cardiovascular surgery literature.6–8 In addition, consensus is lacking regarding the time of discontinuation for higher-risk patients and associated complications.

The clinical impact of ASA prior to elective orthopedic surgery remains uncertain. The purpose of this study was to further determine if ASA dose or time discontinued preoperatively affected surgical outcomes in TJA. The authors hypothesized that ASA worsens surgical outcomes in patients receiving higher doses and in those who discontinue ASA closer to the operative date.

Materials and Methods

The authors performed a retrospective cohort analysis of 2853 patients who underwent primary total knee arthroplasty (TKA) and total hip arthroplasty (THA) at a tertiary medical center from January 2, 2014, to December 20, 2016. After institutional review board approval was obtained, a nurse data abstractor collected the majority of the data through the Michigan Arthroplasty Registry Collaborative Quality Initiative. Patient demographics included age, sex, body mass index (BMI), preoperative American Society of Anesthesiologists score, laterality, and surgery performed (hip or knee). Outcomes included length of stay, emergency department visit with no readmission, readmission (<30 days postoperatively), 90-day postoperative events, intraoperative events, and postoperative blood transfusion. The 90-day postoperative events included deep venous thrombosis, pulmonary embolism, hematoma, joint space infection, and death.

Postoperatively, patients received 24 hours of antibiotic prophylaxis and were mobilized with physical therapy on postoperative day 1. Patients received tranexamic acid per hospital protocol. The protocol stands as 1 g of intravenous tranexamic acid before incision in hips and before tourniquet inflation in knees, and a second 1 g of intravenous tranexamic acid administered throughout closure of the incision. If patients had chronic kidney disease (glomerular filtration rate <50 mL/min), seizure disorder, a recent cerebral infarct (<1 year) or cardiac stent (<1 year), or active deep venous thrombosis or pulmonary embolism, then 2 g of topical tranexamic acid was administered at the time of incision closure. During the period of this study, patients in the authors' hospital system were transfused when hemoglobin was less than 8 mg/dL if symptomatic or if hemoglobin was less than 7 mg/dL. Patients were treated with postoperative anticoagulation per hospital protocol. Patients with no history of prior deep venous thrombosis or pulmonary embolism were given 81 mg of ASA twice a day for 4 weeks starting on postoperative day 0. If patients could not take ASA, then they received 40 mg/d of enoxaparin for 3 weeks. High-risk patients were given 30 mg of enoxaparin twice a day for 4 weeks. If patients were receiving warfarin at home, then 40 mg/d of enoxaparin was administered on postoperative day 1, and warfarin was restarted on postoperative day 0. Once their international normalized ratio was therapeutic, the enoxaparin was discontinued. Those patients taking a factor Xa inhibitor were given half the dose on postoperative day 1 and continued full dosage on postoperative day 7.

Inclusion criteria consisted of primary joint replacement (hip or knee) performed at Henry Ford Hospital System from January 2014 to December 2016. The study excluded any revision procedures, patients who underwent multiple joint replacements within the selected period, patients taking antiplatelet therapy other than ASA (including those receiving combination antiplatelet therapy), and patients taking an ASA dose other than 81 mg or 325 mg. Patients who met selection criteria were stratified by surgery (THA or TKA) and the presence of preoperative ASA. Patients were further stratified based on dosing of ASA, or “low dose” (81 mg) vs “high dose” (325 mg). Patients were then placed into 4 categories to determine if discontinuing ASA further away from their operative date had an effect on outcome. The patients were organized by time to discontinuation, which consisted of less than 4 days, less than 7 days, 7 or more days, and no ASA. Set points were determined based on platelets, return to function, lifespan, and American Academy of Orthopaedic Surgeons recommendations.9–12

All analyses were performed using commercial software (SigmaPlot v.12.3.0.36; Systat Software, Inc, San Jose, California). In all cases, alpha for main effects was set at 0.05. Each analysis was performed (a) for both TKA and THA patients, (b) for TKA patients alone, and (c) for THA patients alone. When the analysis was performed for both joints, joint was additionally considered as a binary variable.

The group of patients receiving ASA (N=1104) was compared with the group not receiving ASA (N=1749) regarding the continuous variables of age, BMI, and preoperative American Society of Anesthesiologists score (as a continuous variable) using a t test and a rank-sum test. Categorical variables of preoperative ASA (as a categorical variable), sex, joint, side, and race were compared between groups using a chi-square analysis.

When a complication could be considered as a binary variable (readmission, 90-day postoperative events, emergency department visit, length of stay [as a binary variable, above or below median], deep venous thrombosis, pulmonary embolism, death, joint space infection, transfusion, or hematoma), the complication was set as the outcome variable in a multiple logistic regression, considering BMI, age, and preoperative American Society of Anesthesiologists score as continuous input variables and preoperative ASA administration as a binary input variable. When a complication could be considered as a continuous variable (length of stay), a multiple linear regression was performed with the same input variables.

A sub-analysis of the data from only those patients who received ASA was considered in the same way, using ASA dose (low or high dose) as a binary variable.

The effect of ASA washout (<4 days, <7 days, 7 or more days, or no ASA given) was considered as a continuous variable in a repeat of the original complications analysis via multiple logistic regressions.

Results

A total of 2853 patients underwent primary THA or TKA during the study period. There were 1802 TKAs (63.2%) and 1051 THAs (36.8%) in the study group. A total of 1104 patients received preoperative ASA (38.7%) (727 TKAs, 377 THAs), whereas 1749 did not (61.3%) (1075 TKAs, 674 THAs).

Overall, patients receiving ASA who underwent TJA had a mean age of 70.0±8.8 years, 54.3% were female, and 85.4% were white (Table 1). Patients receiving ASA were older (69.8±8.8 vs 63.6±10.8 years; P<.001), had a higher American Society of Anesthesiologists score (P<.001), were more likely to be men (P<.001), and were more likely to have a TKA performed (P=.020). Whites were more likely than others to be treated with preoperative ASA if considered in a binary form between whites and blacks (P=.032). There were no statistically significant differences between the groups regarding BMI, side, or race. Compared with the entire TJA group, the TKA patients were older (70.0±8.4 vs 64.1±10.3 years; P<.001), were more likely to be female (P<.001), and had a higher American Society of Anesthesiologists score (P<.001) (Table 2). Compared with the entire TJA group, the THA patients were older (69.4±9.7 vs 62.9±11.5 years; P<.001), were more likely to be male (P<.001), and had a higher American Society of Anesthesiologists score (P<.001) (Table 3).

Demographics of the 2 Groups of Patients Undergoing Total Joint Arthroplasty

Table 1:

Demographics of the 2 Groups of Patients Undergoing Total Joint Arthroplasty

Demographics of the 2 Groups of Patients Undergoing Total Knee Arthroplasty

Table 2:

Demographics of the 2 Groups of Patients Undergoing Total Knee Arthroplasty

Demographics of the 2 Groups of Patients Undergoing Total Hip Arthroplasty

Table 3:

Demographics of the 2 Groups of Patients Undergoing Total Hip Arthroplasty

After controlling for age, joint, BMI, and American Society of Anesthesiologists score, preoperative ASA use was a positive risk factor for readmission (odds ratio [OR], 1.85; 95% confidence interval [CI], 1.34–2.58; P<.001) and 90-day postoperative events (OR, 1.26; 95% CI, 1.09–1.40; P=.004) (Table 4). This was consistent for both the TKA and the THA cohorts. There were no statistically significant differences in emergency department visits, length of stay, deep venous thrombosis, pulmonary embolism, death, joint space infection, transfusion rate, or hematoma.

Preoperative Acetylsalicylic Acid vs No Acetylsalicylic Acida

Table 4:

Preoperative Acetylsalicylic Acid vs No Acetylsalicylic Acid

Regarding ASA dosing, there was no significant difference between patients who received 81 mg twice a day and patients who received 325 mg once a day in any of the studied outcomes (Table 5).

Acetylsalicylic Acid Dose: 81 mg vs 325 mga

Table 5:

Acetylsalicylic Acid Dose: 81 mg vs 325 mg

Finally, the analysis examined the time of preoperative discontinuation of ASA (ie, no ASA, <4 days, <7 days, and 7 or more days). Patients who discontinued ASA 7 or more days prior to TJA had less risk of hematomas (OR, 0.64; 95% CI, 0.42–0.98; P=.038), emergency department visits (OR, 0.79; 95% CI, 0.66–0.93; P=.006), readmission (OR, 0.65; 95% CI, 0.54–0.78; P<.001), and 90-day postoperative events (OR, 0.72; 95% CI, 0.53–0.88; P<.001) (Table 6). Interestingly, these findings had a time effect for patients undergoing TJA: the risk was greater for those who discontinued therapy closer to the operative date (Figure 1). When the patients were divided according to TKA and THA, these results were driven by the TKA patients (Table 6).

Multiple Logistic Regression Comparing Time to Preoperative Discontinuation of Acetylsalicylic Acida

Table 6:

Multiple Logistic Regression Comparing Time to Preoperative Discontinuation of Acetylsalicylic Acid

Time-dependent effects of discontinuing preoperative acetylsalicylic acid (<4 days vs <7 days vs ≥7 days vs no acetylsalicylic acid). Ninety-day postoperative events (90dPE), emergency department (ED) visits, readmission, and hematoma were all significant risk factors the closer to their operative date patients discontinued acetylsalicylic acid. The y-axis is the calculated average of occurrence in the total joint population. The x-axis is the number of days patients discontinued prior to their operative date.

Figure 1:

Time-dependent effects of discontinuing preoperative acetylsalicylic acid (<4 days vs <7 days vs ≥7 days vs no acetylsalicylic acid). Ninety-day postoperative events (90dPE), emergency department (ED) visits, readmission, and hematoma were all significant risk factors the closer to their operative date patients discontinued acetylsalicylic acid. The y-axis is the calculated average of occurrence in the total joint population. The x-axis is the number of days patients discontinued prior to their operative date.

Discussion

This study showed that patients receiving ASA prior to TJA had an increased risk for readmission and 90-day postoperative events compared with patients not receiving ASA. There were no differences in outcomes between patients receiving low-dose ASA (81 mg) vs high-dose ASA (325 mg). Most significantly, patients who discontinued their ASA earlier prior to surgery had decreased risk for postoperative complications, including hematoma, readmission, 90-day postoperative events, and emergency department visits.

Current American Academy of Orthopaedic Surgeons recommendations for preventing venous thromboembolism in patients undergoing elective TJA present moderate-grade evidence to discontinue ASA 5 to 7 days prior to the elective procedure in low-risk individuals.5,12 These recommendations stem from 3 reports on patients undergoing coronary artery bypass grafting, but do not include any studies on patients undergoing elective TJA.13–15 Patients undergoing an elective procedure are generally healthy compared with patients undergoing an emergent procedure. Therefore, as orthopedic surgeons continue to optimize patient care in elective procedures, they must practice evidence-based medicine based on their unique patient population. Manaqibwala et al16 studied the postoperative outcomes of patients receiving antiplatelet therapy following emergent arthroplasty for femoral neck fractures. Similar to the current analysis, patients receiving antiplatelet therapy had increases in 90-day postoperative events following emergent arthroplasty. Manaqibwala et al16 ultimately concluded that the risks of delaying treatment of a traumatic hip fracture outweighed the bleeding risks associated with antiplatelet therapy. However, for an elective TJA, waiting for medical optimization leads to no risk to the patient; therefore, the negative effects of antiplatelet therapy should be considered in surgical candidates.

In the current study, patients receiving ASA were older and had higher American Society of Anesthesiologists scores, which alone increase the risk for readmission and 90-day postoperative events. However, such comorbidities were controlled for and it was determined that preoperative ASA was a risk factor for readmission and 90-day postoperative events. Any risk factor that increases a patient's odds of readmission, emergency department visits, or 90-day postoperative events should be considered when optimizing management for an elective operative procedure. Surgical complications resulting in read-mission have been estimated to cost an average of $45,901 for TKA and $31,880 for THA, but hospitals receive an average reimbursement from Medicare/Medicaid of only $9423 for TKA and $20,517 for THA.17 Unfortunately, many of the current bundling models have rather limited, or no, risk-adjustment techniques for factors such as advanced age, elevated American Society of Anesthesiologists score, preoperative therapy, and major complications. The onus falls on the surgeon to optimize patient risk factors to decrease the risk associated with the surgery.

Recently, multiple studies have found that low-dose ASA is enough to prevent venous thromboembolism18 with less cost19 and bleeding complications20 than other anticoagulants, such as low-molecular-weight heparin and warfarin. To date, the orthopedic literature only reports results for patients receiving low-dose ASA or ASA alone. For patients undergoing percutaneous coronary intervention, Jolly et al21 reported that low-dose ASA appeared to have a lower rate of major bleeding. Prior to Parvizi et al18 reporting the equivalence of low-dose ASA for venous thromboembolism prophylaxis, surgeons at the authors' institution initially used varying doses of ASA. They currently use low-dose ASA (81 mg twice a day) for prophylaxis. On comparison of the two cohorts, the authors found no difference in outcomes between patients receiving high-dose vs low-dose ASA.

Previous studies have compared ASA continuation preoperatively13–15; however, the current authors are unaware of any studies that have determined whether there is an optimal time to discontinue ASA before surgery. The current study did show that patients receiving ASA preoperatively had increased postoperative care in emergency department visits and readmission. In addition, patients who were closer to their operative date at the time of discontinuation had increased risk for postoperative complications encompassed by 90-day postoperative events and hematomas. The main concern regarding continuation of ASA perioperatively is intraoperative bleeding and postoperative bleeding complications. Kallis et al13 determined that there was significantly more blood lost in the group receiving ASA vs the group not receiving ASA (1185 vs 791 mL; P=.001). Firanescu et al14 similarly determined that “when clopidogrel treatment is continued until the day of operation, significantly more blood loss postoperatively . . . has to be anticipated.” Increased intraoperative blood loss leads to an increased rate of transfusion and increased length of stay.15 Although the current cohort showed no increased risk of intraoperative or postoperative transfusion, those undergoing TJA, specifically TKA, did have an increased risk for hematoma. Hematomas can lead to increased postoperative pain, possible infection, and sometimes revision surgery.20

This study had several limitations. Due to the low incidence of the complications studied, a sample size of 2853 provided adequate power to find a difference. However, one could argue that differences may not be strong enough at this sample size. The study was also limited by its retrospective nature. The accuracy of the information cannot be determined, and its completeness varies according to the health professional who charted it. The fact that the information was collected from an entire health care system with multiple hospitals introduces variability in surgical practices and culture. The latter point may reflect an advantage of this study, as data were collected from a large, urban, tertiary care center and from suburban community hospitals, making the conclusions broadly generalizable. An additional strength was that this study received no industry funding or support.

Conclusion

Patients receiving preoperative ASA had higher rates of readmission and 90-day postoperative events. The dose of ASA did not affect any clinical outcomes. Patients who discontinued ASA 7 or more days before TJA had less risk for hematomas, emergency department visits, readmission, and 90-day postoperative events. This study's findings support the American Academy of Orthopaedic Surgeons recommendations to discontinue ASA at least 7 days prior to TJA.

References

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  7. Herman CR, Buth KJ, Kent BA, Hirsch GM. Clopidogrel increases blood transfusion and hemorrhagic complications in patients undergoing cardiac surgery. Ann Thorac Surg. 2010;89(2):397–402. doi:10.1016/j.athoracsur.2009.10.051 [CrossRef]
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  9. Harker LA, Roskos LK, Marzec UM, et al. Effects of megakaryocyte growth and development factor on platelet production, platelet life span, and platelet function in healthy human volunteers. Blood. 2000;95(8):2514–2522.
  10. Lee J, Kim JK, Kim JH, et al. Recovery time of platelet function after aspirin withdrawal. Curr Ther Res Clin Exp. 2014;76:26–31. doi:10.1016/j.curtheres.2014.02.002 [CrossRef]
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  12. Mont MA, Jacobs JJ, Boggio LN, et al. AAOS. Preventing venous thromboembolic disease in patients undergoing elective hip and knee arthroplasty: evidence-based guideline and evidence report. J Am Acad Orthop Surg. 2011;19(12):768–776. doi:10.5435/00124635-201112000-00007 [CrossRef]
  13. Kallis P, Tooze JA, Talbot S, Cowans D, Bevan DH, Treasure T. Pre-operative aspirin decreases platelet aggregation and increases post-operative blood loss: a prospective, randomised, placebo controlled, double-blind clinical trial in 100 patients with chronic stable angina. Eur J Cardiothorac Surg. 1994;8(8):404–409. doi:10.1016/1010-7940(94)90081-7 [CrossRef]
  14. Firanescu CE, Martens EJ, Schönberger JP, Soliman Hamad MA, van Straten AH. Postoperative blood loss in patients undergoing coronary artery bypass surgery after preoperative treatment with clopidogrel: a prospective randomised controlled study. Eur J Cardiothorac Surg. 2009;36(5):856–862. doi:10.1016/j.ejcts.2009.05.032 [CrossRef]
  15. Ghaffarinejad MH, Fazelifar AF, Shirvani SM, et al. The effect of preoperative aspirin use on postoperative bleeding and perioperative myocardial infarction in patients undergoing coronary artery bypass surgery. Cardiol J. 2007;14(5):453–457.
  16. Manaqibwala MI, Butler KA, Sagebien CA. Complications of hip fracture surgery on patients receiving clopidogrel therapy. Arch Orthop Trauma Surg. 2014;134(6):747–753. doi:10.1007/s00402-014-1981-0 [CrossRef]
  17. Clair AJ, Evangelista PJ, Lajam CM, Slover JD, Bosco JA, Iorio R. Cost analysis of total joint arthroplasty readmissions in a bundled payment care improvement initiative. J Arthroplasty. 2016;31(9):1862–1865. doi:10.1016/j.arth.2016.02.029 [CrossRef]
  18. Parvizi J, Huang R, Restrepo C, et al. Low-dose aspirin is effective chemoprophylaxis against clinically important venous thromboembolism following total joint arthroplasty: a preliminary analysis. J Bone Joint Surg Am. 2017;99(2):91–98. doi:10.2106/JBJS.16.00147 [CrossRef]
  19. Davies GC, Salzman EW. Cost effectiveness of prophylaxis of venous thromboembolism. J R Soc Med. 1981;74(3):177–180. doi:10.1177/014107688107400302 [CrossRef]
  20. Tande AJ, Gomez-Urena EO, Berbari EF, Osmon DR. Management of prosthetic joint infection. Infect Dis Clin North Am. 2017;31(2):237–252. doi:10.1016/j.idc.2017.01.009 [CrossRef]
  21. Jolly SS, Pogue J, Haladyn K, et al. Effects of aspirin dose on ischaemic events and bleeding after percutaneous coronary intervention: insights from the PCI-CURE study. Eur Heart J. 2009;30(8):900–907. doi:10.1093/eurheartj/ehn417 [CrossRef]

Demographics of the 2 Groups of Patients Undergoing Total Joint Arthroplasty

CharacteristicReceived Acetylsalicylic AcidDid Not Receive Acetylsalicylic AcidP
Age, mean±SD, y (No.)a69.8±8.8 (1104)63.6±10.8 (1749)<.001
  Rank sum, median, y70.063.0<.001
Body mass index, mean±SD, kg/m2 (No.)a31.9±6.2 (1104)31.9±6.8 (1749).967
  Rank sum, median, kg/m230.931.1.830
American Society of Anesthesiologists score, mean±SD (No.)a2.9±0.5 (1104)2.8±0.6 (1749)<.001
  Rank sum, median3.03.0<.001b
Sex, male/female, No.c504/600645/1104<.001
Joint, knee/hip, No.727/3771075/674.020
Side, left/right/other, No.499/592/13818/892/39.068d
Race, white/black/unknown, No.949/114/401451/224/74.088e
American Society of Anesthesiologists score, No.f<.001
  1615
  2183499
  37981127
  4116107

Demographics of the 2 Groups of Patients Undergoing Total Knee Arthroplasty

CharacteristicReceived Acetylsalicylic AcidDid Not Receive Acetylsalicylic AcidP
Age, mean±SD, y (No.)a70.0±8.4 (727)64.1±10.3 (1075)<.001
  Rank sum, median, y70.064.0<.001
Body mass index, mean±SD, kg/m2 (No.)a32.5±6.2 (727)33.0±6.9 (1074).117
  Rank sum, median, kg/m231.432.3.147
American Society of Anesthesiologists score, mean±SD (No.)a2.9±0.5 (727)2.8±0.6 (1075)<.001
  Rank sum, median3.03.0<.001b
Sex, male/female, No.c296/431347/728<.001
Side, left/right/other, No.337/377/13510/529/36.100d
Race, white/black/unknown, No.620/80/26896/133/46.163e
American Society of Anesthesiologists score, No.f<.001
  139
  2115268
  3541723
  46874

Demographics of the 2 Groups of Patients Undergoing Total Hip Arthroplasty

CharacteristicReceived Acetylsalicylic AcidDid Not Receive Acetylsalicylic AcidP
Age, mean±SD, y (No.)a69.4±9.7 (377)62.9±11.5 (674)<.001
  Rank sum, median, y70.062.0<.001
Body mass index, mean±SD, kg/m2 (No.)a30.7±6.1 (377)30.1±6.1 (674).583
  Rank sum, median, kg/m230.129.5.140
American Society of Anesthesiologists score, mean±SD (No.)a2.9±0.6 (377)2.7±0.6 (674)<.001
  Rank sum, median3.03.0<.001b
Sex, male/female, No.c208/169298/376<.001
Side, left/right/other, No.162/215/0308/363/3.283d
Race, white/black/unknown, No329/14/14555/91/28.483e
American Society of Anesthesiologists score, No.f<.001
  136
  268231
  3257404
  44833

Preoperative Acetylsalicylic Acid vs No Acetylsalicylic Acida

VariableTotal Joint ArthroplastyTotal Knee ArthroplastyTotal Hip Arthroplasty



No.OR (95% CI)PNo.OR (95% CI)PNo.OR (95% CI)P
Readmission1691.85 (1.34–2.58)<.0011111.73 (1.15–2.59).008582.10 (1.19–3.69).010
90-day postoperative event5171.26 (1.09–1.40).0043821.23 (1.02–1.39).0361351.36 (1.06–1.56).022
Emergency department visit2801.26 (0.97–1.64).0882801.21 (0.89–1.65).234791.40 (0.86–2.28).180
Length of stay (continuous).135.114.835
Length of stay (binary)0.97 (0.82–1.15).7090.89 (0.72–1.09).2591.19 (0.89–1.60).233
Deep venous thrombosis471.05 (0.57–1.93).879350.93 (0.46–1.90).841121.39 (0.42–4.00).593
Pulmonary embolus161.45 (0.52–4.03).480131.84 (0.58–5.84).29830.60 (0.05–7.14).689
Death53.83 (0.41–35.94).24032.34 (0.19–28.58).5062<0.01 (0.00-inf).998
Joint space infection201.62 (0.63–4.20).318141.59 (0.52–4.87).41661.82 (0.28–12.04).534
Transfusion1880.88 (0.64–1.21).425790.81 (0.50–1.31).3931090.95 (0.62–1.46).807
Hematoma291.81 (0.83–3.91).135142.10 (0.68–6.50).198151.62 (0.55–4.72).381

Acetylsalicylic Acid Dose: 81 mg vs 325 mga

VariableTotal Joint ArthroplastyTotal Knee ArthroplastyTotal Hip Arthroplasty



No.OR (95% CI)PNo.OR (95% CI)PNo.OR (95% CI)P
Readmission971.34 (0.72–2.51).358631.18 (0.53–2.60).685341.72 (0.61–4.83).300
90-day postoperative event2370.86 (0.16–1.30).6091720.46 (1.16–0.002).161651.41 (0.66–1.74).207
Emergency department visit1230.91 (0.48–1.71).768880.79 (0.37–1.70).544351.33 (0.43–4.05).622
Length of stay (continuous).496.504.628
Length of stay (binary)0.97 (0.64–1.48).8910.78 (0.48–1.27).3201.67 (0.68–4.13).265
Deep venous thrombosis200.93 (0.21–4.11).928140.619 (0.08–4.88).64961.86 (0.21–16.61).578
Pulmonary embolus8<0.001 (0.00-inf).9947<0.001 (0.00-inf).995No PE
Death4<0.001 (0.00-inf).9962<0.001 (0.00-inf).9992<0.001 (0.00-inf).998
Joint space infection9<0.001 (0.00-inf).9957<0.001 (0.00-inf).9952<0.001 (0.00-inf).998
Transfusion760.84 (0.37–1.92).678321.14 (0.38–3.40).818440.59 (0.17–2.07).410
Hematoma161.99 (0.55–7.17).29382.83 (0.56–14.46).21081.29 (0.15–10.95).815

Multiple Logistic Regression Comparing Time to Preoperative Discontinuation of Acetylsalicylic Acida

VariableTotal Joint ArthroplastyTotal Knee ArthroplastyTotal Hip Arthroplasty



No.OR (95% CI)PNo.OR (95% CI)PNo.OR (95% CI)P
Readmission1620.65 (0.54–0.78)<.0011080.57 (0.46–0.72)<.001540.81 (0.58–1.13).220
90-day postoperative event4980.72 (0.53–0.88)<.0013690.68 (0.44–0.88)<.0011290.79 (0.45–1.05).118
Emergency department visit2680.79 (0.66–0.93).0061940.74 (0.60–0.91).004740.89 (0.64–1.23).470
Length of stay (continuous).845.943.721
Length of stay (binary)0.98 (0.87–1.12).7471.01 (0.87–1.18).8570.90 (0.74–1.11).322
Deep venous thrombosis441.18 (0.72–1.89).530321.24 (0.68–2.27).486121.80 (0.49–2.41).837
Pulmonary embolus150.86 (0.42–1.77).689120.73 (0.34–1.56).41831.65 (0.20–13.58).640
Death50.93 (0.35–2.45).87530.97 (0.24–3.86).96320.81 (0.14–4.67).810
Joint space infection200.68 (0.39–1.20).184140.65 (0.35–1.23).18660.83 (0.22–3.06).774
Transfusion1840.90 (0.74–1.11).319140.65 (0.35–1.23).1861070.96 (0.73–1.26).753
Hematoma280.64 (0.42–0.98).038130.58 (0.30–1.09).089150.67 (0.38–1.19).172
Authors

The authors are from the Department of Orthopaedic Surgery, Henry Ford Hospital, Detroit, Michigan.

The authors have no relevant financial relationships to disclose.

Correspondence should be addressed to: Jonathan H. Shaw, MD, Department of Orthopaedic Surgery, Henry Ford Hospital, 2799 W Grand Blvd, Detroit, MI 48067 ( jonathan.shaw86@gmail.com).

Received: January 04, 2019
Accepted: June 03, 2019
Posted Online: August 14, 2019

10.3928/01477447-20190812-01

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