Periprosthetic total hip infections are devastating complications resulting in significant physical, emotional, and financial stress for patients. Most periprosthetic infections are treated with 2-stage exchange arthroplasty, with a success rate ranging from 65% to 93%.1,2 Including hospital stay, reoperation, and prolonged antibiotic therapy, the average total cost of treating a periprosthetic infection is $93,600.3 Methicillin-resistant organisms are even more challenging to treat, often requiring multiple surgical procedures and prolonged antibiotic use. Consequently, methicillin-resistant organisms cost more to treat compared with other infections, costing on average $107,264.4 Despite these efforts, such infections are associated with higher failure rates following 2-stage exchange arthroplasty revision procedures.5 Unfortunately, the infection may never clear in some patients, resulting in possible amputation, resection arthroplasty, or lifelong antibiotic suppression. Given the significant morbidity, potential mortality, and financial cost of periprosthetic infections, there is a need for novel methods to decrease the incidence of surgical site infections (SSIs) in total hip arthroplasty (THA).
Topical vancomycin powder has been identified as a potential adjunct to perioperative antibiotics to decrease the risk of SSI, specifically methicillin-resistant Staphylococcus aureus (MRSA) infection. Several studies have evaluated the efficacy of topical vancomycin for contaminated S aureus implants in rabbit models (in vivo) and have shown a decrease in SSI and biofilm formation on the implants compared with controls.6–8 Several studies in the spine literature have reported decreased SSI with the use of topical vancomycin without increased complications.9–12 However, currently there is a paucity of literature investigating the use of topical vancomycin to prevent SSI following total hip and knee arthroplasty. The studies that do exist suggest that topical vancomycin does not reduce periprosthetic infections, yet these studies are limited by their designs and small samples.13,14 Thus, topical antibiotic use continues to be a subject of debate, with no clear consensus regarding its efficacy.15 Therefore, the current authors sought to investigate the utility of topical vancomycin to prevent SSI following THA and subsequently calculate the cost-effectiveness of this intervention.
Materials and Methods
After institutional review board approval was obtained, a retrospective chart review was undertaken evaluating consecutive primary cementless THAs performed by 5 fellowship-trained arthroplasty surgeons in the authors' hospital system between April 2015 and December 2016. The authors' hospital system has a uniform perioperative protocol with no significant difference in the incidence of postoperative infection (internal quality improvement data). Patients were excluded if they received intravenous vancomycin during the procedure or postoperatively, or if they had a femoral or acetabular component cemented with antibiotic cement. One arthroplasty surgeon (R.L.) routinely used topical vancomycin for primary cementless THA, while the other arthroplasty surgeons did not use topical vancomycin. The use of topical vancomycin for each patient was confirmed in the operative record. One gram of topical vancomycin was used to coat the acetabular and femoral components immediately prior to implantation. This was performed by dipping both components in sterile saline and then coating them with a thin layer of vancomycin powder by hand (Figure 1). The implants were cementless. The implants used in both cohorts were the Pinnacle Acetabular Cup (DePuy, Warsaw, Indiana) and the CORAIL or TRI-LOCK femoral implant (DePuy) based on femoral anatomy and surgeon preference. Both groups of patients received general anesthesia. All patients received weight-based perioperative antibiotics for 24 hours (one dose preoperatively and two doses postoperatively, with cefazolin and, if allergic to penicillin, instead with clindamycin). No drains were used. The choice of venous thromboembolism prophylaxis was left to the treating surgeon.
Both acetabular (A) and femoral (B) components were dipped in sterile saline, coated with a thin layer of topical vancomycin powder by hand, and then implanted.
The charts were reviewed for the following: the need for revision surgery, periprosthetic infection, species of bacterium, and antibiotic sensitivity profile. Periprosthetic infection was defined by the Musculoskeletal Infection Society criteria, and this was confirmed in the chart.16 Additional data collected included age, sex, MRSA nasal swab screening results, smoking history, Charlson Comorbidity Index (both standard and age adjusted), surgical approach, estimated blood loss, immunosuppressant medication use (ie, chronic prednisone, methotrexate, disease-modifying antirheumatic drugs), type of pharmacologic deep venous thromboembolism prophylaxis used, postoperative acute kidney injury, length of hospital stay, discharge disposition, and readmissions.
In addition to characterizing the groups with descriptive statistics, t tests and Fisher's exact tests were used to determine differences between groups. Binomial logistic regression was used to account for confounders that may have been present in this retrospective analysis and to determine risk factors for infection, calculated as an odds ratio and a 95% confidence interval. Statistical significance was set as P<.05 a priori.
An analysis was performed to determine the cost-effectiveness of using topical vancomycin. The absolute risk reduction (ARR) was used to calculate a number needed to treat (NNT). The drug cost was obtained from the inpatient pharmacy of the authors' institution, and the literature was examined to determine the cost of treatment for a prosthetic joint infection (PJI). Together, these were used to determine potential cost savings with empiric use, using the authors' incidence of infection. Furthermore, the costs of vancomycin and postoperative infection were used to determine the ARR (1/NNT) threshold needed for topical vancomycin to be cost-effective:
(costvancomycin)×(NNT)=costinfection, where NNT=1/ARR,
Absolute risk reduction above this threshold would make topical vancomycin cost-effective for preventing infection in this simple model.17
Between April 2015 and December 2016, 309 patients (55.7%) undergoing primary cementless THA were treated with topical vancomycin, and 246 patients (44.3%) were not. The groups were similar in age, sex, body mass index, Charlson Comorbidity Index, age-adjusted Charlson Comorbidity Index, the proportion with positive results for MRSA, and the proportion taking immunosuppressant medications (Table 1). There were significant differences in the proportion of patients who had American Society of Anesthesiologists class 3 or above (vancomycin, 48.9%; no vancomycin, 31.3%; P<.001), the transfusion rate (vancomycin, 0.6%; no vancomycin, 8.9%; P<.001), and the type of deep venous thrombosis prophylaxis used (Table 1).
Characteristics of Included Patients Undergoing Total Hip Arthroplasty
There were 2 infections in the vancomycin group (0.6%) and 4 in the no vancomycin group (1.6%) (Table 2), although this difference did not reach statistical significance (P=.414). The organisms responsible for infection are listed in Table 2. The relative risk of an infection was 0.40 (95% confidence interval, 0.07–2.16). The ARR was 0.98%. With this ARR, the NNT with topical vancomycin was 102 patients to prevent 1 PJI. The proportion of patients who had acute kidney injury was similar in the no vancomycin (0.41%) and the vancomycin (0.97%) groups (P=.436). There were no adverse events attributed to topical vancomycin.
Characteristics of the 6 Patients With Infections
Of the 4 patients with an infection who did not receive topical vancomycin, 3 were American Society of Anesthesiologists class 3 (the other was American Society of Anesthesiologists class 2). All received aspirin as deep venous thrombosis prophylaxis. One patient was taking immunosuppressant medication. None had a positive result on nasal MRSA screening. (Table 2). Of the 2 patients with an infection who did receive topical vancomycin, both were American Society of Anesthesiologists class 3, and both were taking immunosuppressant medication. One of these patients was treated with aspirin and the other with warfarin. Neither had positive results for MRSA.
Multivariable logistic regression indicated that the only significant predictor of postoperative infection was immunosuppression (odds ratio, 17.83; 95% confidence interval, 2.90–108.96; P=.001; Table 3). All other variables included were found not to be significant predictors of infection.
Multivariable Logistic Regression to Determine Risk Factors for Infection After Total Hip Arthroplasty
Each vial of topical vancomycin costs $12 at the authors' institution, and the literature reported a cost of $93,600 per PJI.3 With 4 infections in the no vancomycin group, this corresponded to a total cost of infection of $374,400. When this was divided by the 246 patients in that group, the expected cost per patient was $1521. In the vancomycin group, $3708 ($617 per patient) was spent on the topical vancomycin, and 2 infections cost $187,200. The difference in cost represents an expected per-patient cost savings of $904.
Solving for the ARR threshold at which a $12 vial of topical vancomycin would be cost-effective in preventing a $93,600 postoperative infection, the authors found this break-even point to be 0.01%. If the ARR is at or above this level, then topical vancomycin may be a cost-effective method for PJI prevention.
In the United States, periprosthetic total hip infection is the third most common cause of total hip revision, with a PJI incidence of 0.7% to 2.2%.3,18–20 Kurtz et al3 used the Nationwide Inpatient Sample and found a significantly increased incidence of periprosthetic total hip infections (from 1.99% in 2001 to 2.18% in 2009)—an average 5.3% relative annual increase while accounting for patient demographic factors. Periprosthetic total hip infection is a life-changing complication that causes significant morbidity and mortality and often requires multiple surgical procedures, prolonged hospital stays, long-term intravenous antibiotics, and prolonged rehabilitation and time out of work, all of which cause significant financial stress to the patient and the health care system. The cost of periprosthetic total joint infections to the US health care system was $566 million in 2009, and it is projected to reach $1.62 billion in 2020.3 Owing to the significant health and economic impact of PJIs, there is interest in developing cost-conscious, effective preventive measures; however, there are currently no studies examining the cost-effectiveness of topical vancomycin in THA.
Topical vancomycin has shown promising results in preventing postoperative infection and the development of biofilms in several animal model studies. In a rabbit model, Hovis et al6 implanted a plate-screw construct that was seeded with MRSA in the tibia and subsequently treated half of the subjects (n=9) with 125 mg of topical vancomycin powder (equivalent to 1 g in humans) vs no treatment of the control group. In the experimental topical vancomycin group, not a single bone infection or biofilm was detected. In contrast, in the control group, an infection or biofilm was detected in 67% (6 of 9) of the subjects. Similarly, Zebala et al8 used a rabbit-spine model with 20 rabbits being seeded with methicillin-sensitive S aureus after undergoing a partial laminectomy and wiring. All rabbits received intravenous cefazolin, but only half of the rabbits received topical vancomycin prior to closure. All 10 rabbits in the no vancomycin group had positive results on bacterial cultures from the wound, while all of the rabbits that received vancomycin had negative results on bacterial cultures. There were no adverse events or signs of vancomycin toxicity. Similarly, in a rat femur defect model, Tennent et al21 found that the effectiveness of topical vancomycin for eliminating S aureus was time dependent and greatest if the vancomycin was delivered early to prevent biofilm formation. In the current study, neither of the patients with infections who received vancomycin had cultures indicative of an infection from a gram-positive bacteria. On the other hand, in the no vancomycin group, half of the infections had cultures positive for gram-positive bacteria (methicillin-sensitive S aureus and group B Streptococcus). Finally, neither of the groups had a single culture positive for MRSA.
The beneficial outcomes associated with the use of topical vancomycin in the laboratory have started to be mirrored in the clinical setting, with several recent systematic reviews and meta-analyses showing promising outcomes following the use of topical vancomycin in spine surgery.22–26 In 2014, Chiang et al22 pooled 10 studies and 5888 surgical patients and found topical vancomycin to be significantly protective against SSI (81% decrease), deep incisional SSI (77% decrease), and SSI due to S aureus (78% reduction). A more recent multicenter, prospective cohort study examined 2056 patients undergoing spine surgery and found that not using intrawound vancomycin was the most significant risk factor for both SSI (risk ratio, −2.5; P<.001) and return to the operating room (risk ratio, −5.9; P<.001).27 Although promising, such studies should be read with caution, as the evidence levels are low, proving the need for more high-quality, prospective, randomized controlled trials.
Investigations of topical vancomycin use specifically in arthroplasty have been infrequent, retrospective, and underpowered. Lum et al13 found no statistically significant difference between THA and total knee arthroplasty patients treated with and without topical vancomycin, although their retrospective cohort study included only 208 patients. Similarly, Khatri et al14 retrospectively compared 115 patients undergoing total knee arthroplasty and found no significant difference in postoperative infections. Johnson et al28 investigated the serum and wound concentrations of vancomycin after intrawound application during total joint arthroplasty. They found both highly therapeutic intrawound concentrations and low systemic concentrations, concluding that vancomycin may be a safe adjunctive therapy. The current authors have presented the largest study to date examining the use of topical vancomycin in THA and reported a decrease in periprosthetic hip infections following the use of topical vancomycin. However, this difference did not reach statistical significance, likely because of the relative rarity of infection.
In addition to the devastating clinical consequences, PJI is tremendously costly for patients, providers, insurers, and society. With a cost of just $12 per vial, the expected cost savings of using topical vancomycin in THA is $904 per patient. This is consistent with cost-effectiveness studies in the spine literature, which have reported the possibility for significant cost savings of up to $4400 per case.29,30 At a cost of $12 per 1-g vial of vancomycin, the break-even point of ARR is only 0.01%, which suggests that this is a cost-conscious strategy to reduce infection. This risk reduction is sensitive only to the costs of the drug and the complication and not to the incidence of infection, making it relevant in many different scenarios. The authors' institution's cost is within the $5 to $40 range reported in the literature.
Topical vancomycin has proven to be safe and without significant adverse events, although significant variation in dosing exists. DeFrancesco et al31 found only 1 potential mild adverse reaction (transient rash resolving without intervention) in 1398 pediatric scoliosis patients at 11 centers. A prospective study found no adverse effects from either 1 or 2 g of subfascial vancomycin powder.12 Several retrospective spine studies have found a decrease in SSI with the use of topical vancomycin without adverse events.9–11,32 Similar to previous in vivo rabbit models using topical vancomycin and retrospective human studies, the current authors observed no adverse events with topical vancomycin. They also did not observe a difference in episodes of acute kidney injury between the groups, which may have been related to the administration of topical vancomycin powder.
When prophylactic antibiotics are used, the risk of increasing antibiotic resistance must be considered. Although the data are limited, and additional studies are warranted, existing data suggest that vancomycin overuse alone does not increase the risk of antibiotic resistance, but rather that vancomycin-resistant bacterial strains occur only in the event of bacterial co-infections.33 Furthermore, previous studies have shown intermediate resistant strains to only be resistant to vancomycin at concentrations between 4 and 8 µg/mL. Fortunately, when given topically, the local concentration of vancomycin far exceeds this level and therefore inhibits the propagation of resistant strains.34
The current study had several limitations. First, the patients were reviewed retrospectively and were not prospectively randomized to different treatments, which may have introduced selection and treatment biases, potentially confounding the results. Furthermore, not every comorbidity was collected and analyzed separately; instead, comorbidities were categorized using other variables such as the American Society of Anesthesiologists classification and the Charlson Comorbidity Index. Prosthetic joint infections following primary THA are rare events, and the current study was not adequately powered to detect a difference. A post hoc power analysis found that, with the infection rates and group sizes, there was a 20.6% power to detect a difference between groups. This is lower than the 80% that is commonly used in sample size determinations. A further calculation to determine the adequate sample size for the incidence of infections found that 3682 patients would need to be enrolled. Therefore, the NNT and cost analyses may have relied on incorrect assumptions, although the cost-effectiveness threshold for ARR is not dependent on these.
Periprosthetic joint infections are devastating complications with significant morbidity, mortality, and cost. Topical vancomycin is inexpensive and cost-effective. Although not statistically significant, the topical vancomycin group had a 60% lower incidence of infection. The NNT to prevent 1 PJI is 102 patients, which translates to $904 saved per patient with topical vancomycin. Ultimately, further research regarding appropriate prophylactic topical and intravenous antibiotic use is needed prior to widespread adoption.
- Senthi S, Munro JT, Pitto RP. Infection in total hip replacement: meta-analysis. Int Orthop. 2011;35(2):253–260. doi:10.1007/s00264-010-1144-z [CrossRef]
- Parvizi J, Zmistowski B, Adeli B. Periprosthetic joint infection: treatment options. Orthopedics. 2010;33(9):659.
- Kurtz SM, Lau E, Watson H, Schmier JK, Parvizi J. Economic burden of periprosthetic joint infection in the United States. J Arthroplasty. 2012;27(8)(suppl):61S–65S. doi:10.1016/j.arth.2012.02.022 [CrossRef]
- Parvizi J, Pawasarat IM, Azzam KA, Joshi A, Hansen EN, Bozic KJ. Periprosthetic joint infection: the economic impact of methicillin-resistant infections. J Arthroplasty. 2010;25(6)(suppl):103S–107S. doi:10.1016/j.arth.2010.04.011 [CrossRef]
- Leung F, Richards CJ, Garbuz DS, Masri BA, Duncan CP. Two-stage total hip arthroplasty: how often does it control methicillin-resistant infection?Clin Orthop Relat Res. 2011;469(4):1009–1015. doi:10.1007/s11999-010-1725-6 [CrossRef]
- Hovis JP, Montalvo R, Marinos D, et al. Intraoperative vancomycin powder reduces Staphylococcus aureus surgical site infections and biofilm formation on fixation implants in a rabbit model. J Orthop Trauma. 2018;32(5):263–268. doi:10.1097/BOT.0000000000001136 [CrossRef]
- Liu G, Chen S, Fang J, et al. Vancomycin microspheres reduce postoperative spine infection in an in vivo rabbit model. BMC Pharmacol Toxicol. 2016;17(1):61. doi:10.1186/s40360-016-0105-6 [CrossRef]
- Zebala LP, Chuntarapas T, Kelly MP, Talcott M, Greco S, Riew KD. Intrawound vancomycin powder eradicates surgical wound contamination: an in vivo rabbit study. J Bone Joint Surg Am. 2014;96(1):46–51. doi:10.2106/JBJS.L.01257 [CrossRef]
- Hey HW, Thiam DW, Koh ZS, et al. Is intraoperative local vancomycin powder the answer to surgical site infections in spine surgery?Spine (Phila Pa 1976). 2017;42(4):267–274. doi:10.1097/BRS.0000000000001710 [CrossRef]
- Schroeder JE, Girardi FP, Sandhu H, Weinstein J, Cammisa FP, Sama A. The use of local vancomycin powder in degenerative spine surgery. Eur Spine J. 2016;25(4):1029–1033. doi:10.1007/s00586-015-4119-3 [CrossRef]
- Thompson GH, Poe-Kochert C, Hardesty CK, Son-Hing J, Mistovich RJ. Does vancomycin powder decrease surgical site infections in growing spine surgery? A preliminary study. J Bone Joint Surg Am. 2018;100(6):466–471. doi:10.2106/JBJS.17.00459 [CrossRef]
- Murphy EP, Curtin M, Shafqat A, Byrne F, Jadaan M, Rahall E. A review of the application of vancomycin powder to posterior spinal fusion wounds with a focus on side effects and infection: a prospective study. Eur J Orthop Surg Traumatol. 2017;27(2):187–191. doi:10.1007/s00590-016-1878-4 [CrossRef]
- Lum Z, Ummel J, Coury J, Huff K, Cohen J, Casey J. No change in infection rates with intraoperative vancomycin powder in total joint arthroplasty. Orthop Proc. 2018;100B(suppl 4):53.
- Khatri K, Bansal D, Singla R, Sri S. Prophylactic intrawound application of vancomycin in total knee arthroplasty. J Arthrosc Joint Surg. 2017;4(2):61–64. doi:10.1016/j.jajs.2017.08.001 [CrossRef]
- Cooper C, Horner C, Barlow G, et al. A survey of practice and opinions on the use of topical antibiotics to prevent surgical site infection: more confusion than consensus. J Antimicrob Chemother. 2018;73(7):1978–1983. doi:10.1093/jac/dky097 [CrossRef]
- Parvizi J, Gehrke TInternational Consensus Group on Periprosthetic Joint Infection. Definition of periprosthetic joint infection. J Arthroplasty. 2014;29(7):1331. doi:10.1016/j.arth.2014.03.009 [CrossRef]
- Hatch MD, Daniels SD, Glerum KM, Higgins LD. The cost effectiveness of vancomycin for preventing infections after shoulder arthroplasty: a break-even analysis. J Shoulder Elbow Surg. 2017;26(3):472–477. doi:10.1016/j.jse.2016.07.071 [CrossRef]
- Bozic KJ, Kurtz SM, Lau E, Ong K, Vail TP, Berry DJ. The epidemiology of revision total hip arthroplasty in the United States. J Bone Joint Surg Am. 2009;91(1):128–133. doi:10.2106/JBJS.H.00155 [CrossRef]
- Pulido L, Ghanem E, Joshi A, Purtill JJ, Parvizi J. Periprosthetic joint infection: the incidence, timing, and predisposing factors. Clin Orthop Relat Res. 2008;466(7):1710–1715. doi:10.1007/s11999-008-0209-4 [CrossRef]
- Ong KL, Kurtz SM, Lau E, Bozic KJ, Berry DJ, Parvizi J. Prosthetic joint infection risk after total hip arthroplasty in the Medicare population. J Arthroplasty. 2009;24(6)(suppl):105S–109S. doi:10.1016/j.arth.2009.04.027 [CrossRef]
- Tennent DJ, Shiels SM, Sanchez CJ Jr, et al. Time-dependent effectiveness of locally applied vancomycin powder in a contaminated traumatic orthopaedic wound model. J Orthop Trauma. 2016;30(10):531–537. doi:10.1097/BOT.0000000000000617 [CrossRef]
- Chiang HY, Herwaldt LA, Blevins AE, Cho E, Schweizer ML. Effectiveness of local vancomycin powder to decrease surgical site infections: a meta-analysis. Spine J. 2014;14(3):397–407. doi:10.1016/j.spinee.2013.10.012 [CrossRef]
- Xiong L, Pan Q, Jin G, Xu Y, Hirche C. Topical intrawound application of vancomycin powder in addition to intravenous administration of antibiotics: a meta-analysis on the deep infection after spinal surgeries. Orthop Traumatol Surg Res. 2014;100(7):785–789. doi:10.1016/j.otsr.2014.05.022 [CrossRef]
- Xie LL, Zhu J, Yang MS, et al. Effect of intra-wound vancomycin for spinal surgery: a systematic review and meta-analysis. Intra-wound vancomycin in spine surgery. Orthop Surg. 2017;9(4):350–358. doi:10.1111/os.12356 [CrossRef]
- Khan NR, Thompson CJ, DeCuypere M, et al. A meta-analysis of spinal surgical site infection and vancomycin powder: a review. J Neurosurg Spine. 2014;21(6):974–983. doi:10.3171/2014.8.SPINE1445 [CrossRef]
- Bakhsheshian J, Dahdaleh NS, Lam SK, Savage JW, Smith ZA. The use of vancomycin powder in modern spine surgery: systematic review and meta-analysis of the clinical evidence. World Neurosurg. 2015;83(5):816–823. doi:10.1016/j.wneu.2014.12.033 [CrossRef]
- Devin CJ, Chotai S, McGirt MJ, et al. Intrawound vancomycin decreases the risk of surgical site infection after posterior spine surgery: a multicenter analysis. Spine (Phila Pa 1976). 2018;43(1):65–71. doi:10.1097/BRS.0000000000001371 [CrossRef]
- Johnson JD, Nessler JM, Horazdovsky RD, Vang S, Thomas AJ, Marston SB. Serum and wound vancomycin levels after intrawound administration in primary total joint arthroplasty. J Arthroplasty. 2017;32(3):924–928. doi:10.1016/j.arth.2015.10.015 [CrossRef]
- Emohare O, Ledonio CG, Hill BW, Davis RA, Polly DW Jr, Kang MM. Cost savings analysis of intrawound vancomycin powder in posterior spinal surgery. Spine J. 2014;14(11):2710–2715. doi:10.1016/j.spinee.2014.03.011 [CrossRef]
- Godil SS, Parker SL, O'Neill KR, Devin CJ, McGirt MJ. Comparative effectiveness and cost-benefit analysis of local application of vancomycin powder in posterior spinal fusion for spine trauma: clinical article. J Neurosurg Spine. 2013;19(3):331–335. doi:10.3171/2013.6.SPINE121105 [CrossRef]
- DeFrancesco CJ, Flynn JM, Smith JT, et al. Children's Spine Study Group. Clinically apparent adverse reactions to intra-wound vancomycin powder in early onset scoliosis are rare. J Child Orthop. 2017;11(6):414–418. doi:10.1302/1863-2548.11.170107 [CrossRef]
- Armaghani SJ, Menge TJ, Lovejoy SA, Mencio GA, Martus JE. Safety of topical vancomycin for pediatric spinal deformity: nontoxic serum levels with supratherapeutic drain levels. Spine (Phila Pa 1976). 2014;39(20):1683–1687. doi:10.1097/BRS.0000000000000465 [CrossRef]
- McGuinness W, Malachowa N, Deleo F. Vancomycin resistance in Staphylococcus aureus. Yale J Biol Med. 2017;90(2):269–281.
- Appelbaum PC. The emergence of vancomycin-intermediate and vancomycin-resistant Staphylococcus aureus. Clin Microbiol Infect. 2006;12(1):16–23. doi:10.1111/j.1469-0691.2006.01344.x [CrossRef]
Characteristics of Included Patients Undergoing Total Hip Arthroplasty
|Age, mean±SD (range), y||67.3±12.6 (17–96)||66.0±10.2 (23–93)||.180|
|Male, No. (%)||109 (44.3)||149 (48.2)||.359|
|Body mass index, mean±SD (range), kg/m2||29.2±5.6 (14.1–44.4)||29.6±5.8 (17.1–47.3)||.364|
|ASA class, mean±SD (range)||2.3±0.5 (1–4)||2.5±0.6 (1–4)||<.001a|
|ASA class 1 or 2, No. (%)||169 (68.7)||158 (51.1)|
|ASA class 3 or above, No. (%)||77 (31.3)||151 (48.9)||<.001a|
|CCI, mean±SD (range)||1.0±1.2 (0–5)||1.0±1.3 (0–5)||.405|
|Age-adjusted CCI, mean±SD (range)||3.3±2.0 (0–9)||3.2±1.9 (0–8)||.691|
|Immunosuppressed, No. (%)||12 (4.9)||10 (3.2)||.325|
|MRSA positive, No. (%)||5 (2.0)||11 (3.6)||.319|
|Transfusion, No. (%)||22 (8.9)||2 (0.6)||<.001a|
|Postoperative DVT prophylaxis, No. (%)||<.001a|
| Aspirin||225 (91.5)||192 (62.1)|
| Warfarin||14 (5.7)||109 (35.3)|
| Other||7 (2.8)||7 (2.3)|
| None||0 (0)||1 (0.3)|
Characteristics of the 6 Patients With Infections
|Age, y||Sex||BMI, kg/m2||ASA Class||MRSA Swab Result||Immunosuppressant Medication||Topical Vancomycin||DVT Prophylaxis||Discharge Disposition||Microorganism|
|91||Male||20.5||3||Negative||None||No||Aspirin||Rehab||Group B Streptococcus|
|77||Female||30.9||3||Negative||Chronic prednisone||No||Aspirin||Rehab||Enterobacter cloacae|
|46||Female||35.3||2||Negative||None||No||Aspirin||Home||Methicillin-sensitive Staphylococcus aureus|
|67||Male||27.5||3||Negative||Chronic prednisone||Yes||Warfarin||Home||Culture negative|
|61||Female||30.3||3||Negative||Methotrexate, adalimumab||Yes||Warfarin||Home||Escherichia coli|
Multivariable Logistic Regression to Determine Risk Factors for Infection After Total Hip Arthroplastya
|Risk Factor||Odds Ratio||95% Confidence Interval||P|
|Age (per year)||0.93||0.84–1.04||.192|
|Body mass index (per unit)||1.00||0.86–1.18||.951|
|American Society of Anesthesiologists classification (per class)||6.07||0.37–98.87||.205|
|Discharge to a rehabilitation facility||0.75||0.08–0.67||.750|