The Journal of Arthroplasty 29 (2014) 895–899
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The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
The Increased Total Cost Associated With Post-Operative Drains in Total Hip and Knee Arthroplasty Benjamin T. Bjerke-Kroll, MD, MS, Peter K. Sculco, MD, Alexander S. McLawhorn, MD, MBA, Alexander B. Christ, MD, Brian P. Gladnick, MD, David J. Mayman, MD Hospital for Special Surgery, New York, New York
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Article history: Received 4 September 2013 Accepted 30 October 2013 Keywords: cost-effectiveness arthroplasty post-operative suction device blood loss transfusion length of stay
a b s t r a c t In a consecutive series of 536 unilateral primary total hip arthroplasties (THAs) and 598 unilateral primary total knee arthroplasties (TKAs), the use of a post-operative drain was associated with $538 additional cost per THA, and $455 for TKA. The use of a drain increased hospital length of stay (LOS) for THA, but not for TKA. In both groups, the use of a drain increased estimated blood loss (EBL) and increased the amount of allogeneic blood transfused. Over the 10-week period, drain use was associated with a total cost of $432,972 for our institution. Data from this study would favor a selective approach to the use of drains in primary joint arthroplasties. © 2014 Elsevier Inc. All rights reserved.
In the United States, over 900,000 total hip or total knee arthroplasties were performed in 2012 at a cost of $42.3B [1]. Osteoarthritis is the now the most frequent cause of disability in the United States, and over 10% of the US population reports symptomatic osteoarthritis [1,2]. In modern lower extremity arthroplasty, an estimated 7%–53% of these patients will require blood transfusion [3–5], at a cost of $522–$1183 per unit [6]. Any significant decrease in peri-operative transfusion rate or overall cost of arthroplasty will result in major health care cost reduction.
Materials and Methods This study was conducted in a high-volume tertiary-care private teaching hospital in an urban setting. All primary unilateral hip and knee arthroplasties performed during a 10-week period were included, regardless of surgeon, surgeon training or subspecialty,
Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. None of the authors, or their institution(s), have had any financial relationship, in the thirty-six months prior to submission of this work, with any entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. Also, no author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The Conflict of Interest statement associated with this article can be found at http://dx.doi.org/10.1016/j.arth.2013.10.027. Reprint requests: Benjamin T. Bjerke-Kroll, MD, Hospital for Special Surgery, 535 E 70th St, New York, NY 10021. 0883-5403/2905-0007$36.00/0 – see front matter © 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.arth.2013.10.027
anesthetic technique, implant selection, patient demographics, anticoagulation or post-operative protocols. The study received approval by the institutional review board at the authors’ institution. An electronic search of all hospital records was conducted over an arbitrary 10-week period (October 2010 to December 2010). 1341 patients with ICD-9 codes 81.51 (THA) and 81.54 (TKA) were identified. Patients were included if the following information were available: height, weight, pre-operative hemoglobin (Hb) within 30 days of the procedure, Hb values recorded for post-operative days 1 and 2, anticoagulant used, recorded use or non-use of a drain, and drain output, when applicable. Patients were excluded if they received bilateral surgery, hemiarthroplasty, hip resurfacing, unicondylar knee arthroplasty. There were no data collected beyond the initial hospitalization period. Additional exclusion criteria included pre-operative fracture, pre-existing coagulopathy, or any concomitant procedure, including removal of hardware, arthrocentesis, and tenotomy. 536 THAs and 598 TKAs were included in the current study. These were performed by 42 surgeons. THA and TKA data were analyzed separately. Data collected included procedure, gender, date of birth, LOS, surgeon, pre-operative Hb, all available Hb values throughout the hospital stay, amount and type of all blood products transfused throughout the hospital stay, and presence of a drain with any associated output. Radiographs were analyzed if there was a question of procedure performed or presence of pre-existing hardware. Post-operative care and decision-making regarding blood product transfusion, drain removal, and discharge date are managed by attending surgeons, attending medical physicians, resident physicians, and physician assistants. A standardized post-operative transfusion protocol is utilized by the hospital and all housestaff with recommended transfusion thresholds. The recommended transfusion
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threshold for all post-operative patients is Hb b 8.0 dL, unless otherwise specified by the patient’s internist or surgeon. For all surgeons, drains were placed to suction immediately post-operatively, and suction remained in place until removal unless an exceptional amount of drainage was noted, in which case the drain was placed temporarily to gravity. During the study period, drains were routinely removed on the first post-operative day, unless an exceptional output was noted and the drain was left in place for an additional 24 h. Estimated Blood Loss Calculation The following formula, as originally described by Nadler et al [7,8], was used to calculate estimated blood volume (EBV): Males: EBV ¼ 1000
3
0:3669 height
þ ð0:03219 weightÞ; þ0:6041
þ ð0:03308 weightÞ; þ0:1833
Females: EBV ¼ 1000
3
0:3561 height
Height and weight are measured in meters and kilograms, respectively. EBL was estimated using the following formulas [7,8]: Hbloss ¼ EBV ðHbi −Hbe Þ 0:001 þ Hbt EBL ¼ 1000 Hbloss =Hbi
the cost per transfusion, and 3) the cost of the drainage device. The following equation was used to estimate the cost associated with drain use: fðLOSdrain −LOSno drain Þ 2011g þ fðTxdrain −Txno drain Þ 761g þ 35 Where LOS represents average length of hospital stay for each group, $2011 is the cost per day, Tx represents the mean number of transfused units per patient, $761 is the cost per transfusion, and $35 represents the cost of the drain. Drain Use by Surgeon Preference Our study was designed to select for a large cross-section of patients without coagulatopathy. However, certain intra-operative factors may account for a noticeable difference in blood loss or postoperative drainage, and may prompt the operating surgeon to elect for or against the use of a drainage device. Our observation before initiation of the study is that the use of a drain is more surgeondependent, and less dependent on intra-operative events or patient characteristics. For this reason, we performed a secondary analysis of drain usage by surgeon. We considered the surgeon to be “selective” if a drain was placed in 10%–90% of cases for a particular operation, otherwise the surgeon was considered “non-selective”. Statistical Methods
Hbi represents the initial hemoglobin concentration in g/dL, Hbe represents a subsequent hemoglobin concentration, and Hbt represents the amount of Hb transfused in grams. For this study, Hbe was defined as the last Hb recorded during the hospital stay. In order to estimate the amount of Hb per transfusion (Hbt), 25 samples of autologous and 25 samples of allogeneic blood were chosen at random from our blood bank. All were analyzed (ADVIA 120, Siemens AG, Erlangen, Germany) for total volume and Hb density (Hbt = Hb × V). On average, one unit of autologous and allogeneic blood contained 56.3 ± 5.7 g and 58.1 ± 7.9 g of Hb, respectively. There was no significant difference between these blood products, and little variation between samples. Cost Determination The impact of hospital stay on cost was calculated assuming a cost of $2011 per day, as determined by an independent source of healthcare research for all hospital stays [9] and adjusted for 2012 [10]. This estimate is conservative, given the Healthcare Cost and Utilization Project estimate of $2500 per hospital day in 2009 [11]. The total cost of a transfused unit of autologous or allogeneic blood was calculated to be $761 [6]. This is consistent with prior estimates [12,13] The drain device utilized by our institution is the ConstaVac (Stryker, Kalamazoo, MI) and represents a $35 cost per device to the authors’ institution. The total cost associated with drain use will be a sum of the following: 1) the difference in LOS for both groups multiplied by the cost per hospital day, 2) the difference in transfusions multiplied by
A Student’s t test was used to examine statistical significance for all groups individually, as well as overall cost differential. Results There were no significant demographic or pre-operative differences between THA patients who received a drain and those who did not (Table 1). Likewise, there were no demographic or pre-operative differences in the TKA cohort. Of 536 THA patients studied, 62% received a drainage device. Of 598 TKA patients studied, 88% received a drainage device. The use of a drain significantly increased LOS for THA (3.52 ± 1.1 days vs 3.30 ± 0.8, P b 0.01) but not for TKA (4.01 ± 1.2 days vs 3.93 ± 1.0, P N 0.05) (Tables 2 and 3). In both groups, the use of a drain significantly increased EBL (THA: 1298 mL vs 1215, P b 0.05; TKA: 1575 vs 1375, P b 0.001). The drain group received a significantly increased amount of allogeneic blood transfused (THA: 0.24 vs 0.16 U, P b 0.05; TKA: 0.54 vs 0.20 U, P b 0.05). The additional cost per patient associated with drain use was $538 for THA and $455 for TKA (Table 4). Over the 10-week period of investigation in our hospital, the total associated cost for drains was: TKA: $538 × 524 = $281,912 THA: $455 × 332 = $151,060 Total cost: $432,972 All drains in this study period were removed by the second postoperative day.
Table 1 Comparison of Groups by Procedure and Drain Selection. Patient Characteristics N Male:Female Age (year) Weight (kg) BMI (kg/m2) Pre-ob Hb (g/dL)
THA Drain 332 146:185 65.8 ± 11.0 81.3 ± 19.1 28.3 ± 5.6 13.6 ± 1.3
TKA No Drain 204 93:101 66.4 ± 79.4 ± 27.6 ± 13.5 ±
10.7 19.5 5.5 1.4
P
Drain
0.28 0.14 0.092 0.14
524 226:298 68.2 ± 9.9 86.9 ± 19.1 30.7 ± 6.0 13.3 ± 1.5
No Drain 74 28:46 69.3 ± 84.8 ± 30.1 ± 13.3 ±
9.2 15.9 6.1 1.4
P
0.055 0.15 0.22 0.49
B.T. Bjerke-Kroll et al. / The Journal of Arthroplasty 29 (2014) 895–899 Table 2 Comparison of THA Outcome Measures by Drain Use.
n LOS (days) EBL (mL) Homologous Transfusion (U)
Table 4 Analysis of Drain Usage by Surgeon.
Drain
No Drain
332 3.52 ± 1.1 1298 ± 449 0.24
204 3.30 ± 0.8 1215 ± 429 0.16
P 0.004 0.017 0.047
The average total recorded drain output was 245 ± 207 mL for THA, and 623 ± 296 mL for TKA. All patients received aspirin (325 mg orally twice per day) or warfarin (based on INR) during the immediate post-operative hospitalization period; there were no other types of pharmacologic anti-coagulation used in this patient population during the study period. When drain usage and procedures were controlled for, the warfarin group was consistently older (although significant for only one group) and had a higher BMI (significant for two groups, excluding TKAs without a drain due to the low number of patients). For the warfarin group, EBL was higher in all groups (significantly in one) and LOS was longer (significant in three of four groups). No difference in transfusion rate could be found between groups. All data are listed in Tables 5 and 6. No patient received reinfusion from the drainage device. THAs were performed by 42 different surgeons, and TKAs were performed by 25 different surgeons during the study period. For TKAs, 83.3% (35/42) of surgeons utilized a drain in 0% or 100% of their cases, and 4.7% (2/42) of surgeons were “selective”. For THAs, 52.0% (13/25) of surgeons utilized a drain in 0% or 100% of patients, and 12.0% (3/25) of surgeons were “selective”. Discussion The use of wound drains after arthroplasty surgery has been controversial [14–16]. Arguments for drain devices include a theoretical decreased risk of surgical site infection [17] and decreased hematoma formation, which may limit range of motion. Others argue that drains do not affect range of motion, serve as a portal for infection, increase post-operative blood loss and need for transfusion. Empirically, drains have been shown to decrease the size of postoperative effusion [18] but not affect TKA range of motion [19–22], decrease ecchymosis [23], increase peri-operative blood loss [24–26], and increase the need for blood transfusion postoperatively [15,19,25,26]. They have been shown to have no effect on wound healing [27], deep venous thrombosis [22] or postoperative infection rate [22]. At our institution, drain use in primary lower extremity arthroplasty over a 10-week period was associated at a cost of over $400,000. If a measurable benefit can be shown from future studies with drain use, these data may provide a baseline for costeffectiveness. To our knowledge, this is the first study that investigated the costs associated with drain use after total joint arthroplasty. Drains have been shown to be cost-effective when used with a post-operative reinfusion protocol for both THA [28] and TKA [29]. However, in the absence of reinfusion, the use of a drainage device has not been studied with regard to cost.
Table 3 Comparison of TKA Outcome Measures by Drain Use.
N LOS EBL (mL) Homologous Transfusion (U)
897
Drain
No Drain
P
524 4.01 ± 1.2 1575 ± 496 0.54
74 3.93 ± 1.0 1375 ± 456 0.20
0.113 0.0004 0.036
TKA
THA
Surgeon
Drain
None
% Drain
Drain
None
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42
0 5 29 24 4 6 1 2 1 19 1 10 43 1 2 76 2 4 2 11 21 5 16 7 12 26 9 13 14 15 3 3 18 4 15 26 5 0 8 23 7 31
12 0 2 0 0 0 37 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 1 2 0 0 0 0 0 0 0 16 0 0 1 0
0% 100% 94% 100% 100% 100% 3% 100% 100% 100% 100% 100% 96% 100% 100% 100% 100% 100% 100% 100% 100% 100% 94% 100% 100% 100% 100% 100% 93% 88% 100% 100% 100% 100% 100% 100% 100% 0% 100% 100% 88% 100%
2 0 5 1 14 0 30 0 0 30 0 0 2 0 0 2 0 1 0 0 12 4 22 0 29 10 0 4 30 19 1 0 9 1 50 29 0 2 0 20 0 3
22 0 35 32 0 0 0 0 0 0 0 0 15 0 0 0 0 0 0 0 11 1 0 0 0 6 0 56 0 1 0 0 0 0 1 1 0 22 0 0 0 0
% Drain 8% – 13% 3% 100% – 100% – – 100% – – 12% – – 100% – 100% – – 52% 80% 100% – 100% 63% – 7% 100% 95% 100% – 100% 100% 98% 97% – 8% – 100% – 100%
Surgeons in bold performed over 10 of the specified procedure.
This current study suggests that the use of wound drains is associated with a significant increase in cost during a patient’s hospital stay for primary unilateral knee and hip arthroplasty. A secondary analysis of these data has shown use of a wound drain to increase postoperative blood loss and transfusion requirements for both procedures, while length of hospital stay was significantly increased for THA. The current study has several limitations. It investigates a large and relatively unfiltered data set and therefore could be biased. However, it does therefore give an overview over a variety of different surgical techniques and is more representative of overall care and cost at a large orthopedic specialty hospital. One advantage of this study is the large number of patients collected in a short period of time. Changes in treatment protocols and surgical technique are unlikely to change significantly over a 10-week period. One limitation of a retrospective review is that we do not know the individual justification for use of a drain for each patient. A possible confounding association in this study is a more noticeable appearance of intra-operative bleeding may prompt the surgeon to place a drain that otherwise would not; similarly a “dry” surgical field may cause the surgeon to forgo the use of a drain. It is our impression that this is the exception, and that most surgeons place a drain based on convention, rather than intra-operative appearance. Our review of drain use by surgeon supports this for most surgeons; the majority of surgeons use a drain in less than 10% or over 90% of cases.
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Table 5 Comparison of THAs by Drain Usage and Anti-Coagulation. Drain
n Male Female Age BMI Pre-ob Hb EBL LOS Transfusions
No Drain
Aspirin
Warfarin
246 103 143 65.8 ± 10.5 27.7 ± 5.2 13.6 ± 1.3 1289 ± 440 3.4 ± 1.0 0.2
86 44 42 68.3 ± 11.3 29.8 ± 6.8 13.7 ± 2.0 1351 ± 488 3.9 ± 1.3 0.36
P
Aspirin
0.063 0.033 0.6 0.28 0.0003 0.093
147 70 77 65.0 ± 27.4 ± 13.6 ± 1190 ± 3.2 ± 0.16
Warfarin 57 23 34 67.1 ± 28.0 ± 13.1 ± 1282 ± 3.5 ± 0.14
10.6 5.4 1.3 417 0.7
12.5 5.9 1.5 457 0.8
P
b 0.0001 0.49 0.019 0.17 0.009 0.26
Table 6 Comparison of TKAs by Drain Usage and Anti-Coagulation. Drain
n Male Female Age BMI Pre-ob Hb EBL LOS Transfusions
No Drain
Aspirin
Warfarin
46 19 27 65.8 ± 10.5 28.8 ± 4.6 13.3 ± 1.9 1422 ± 582 3.7 ± 1.0 0.46
478 207 271 68.0 ± 10.3 30.9 ± 6.0 13.3 ± 1.4 1590 ± 485 4.5 ± 0.7 0.33
It is important to translate the data to clinical application in our study: blood cannot be transfused in a fraction of a unit, nor can a patient be hospitalized for a fraction of a day with a meaningful significance with regard to cost. A more meaningful measure may be to discuss our findings with regard to 100 patients. For example, stating that drain use with TKA increased the rate of transfusion from 20 U to 54 U per 100 arthroplasties; drain use with THA increased the rate of transfusion from 16 U to 24 U per 100 arthroplasties. Anti-coagulation use was recorded to investigate a possible correlation with post-operative blood loss. As we suspected, warfarin use is a predictor of higher BMI and older age, which may be accounted for in their inherent increased risk of thrombus and/or embolism. Nonetheless, there did not appear to be differences in overall transfusion rate. Because of the confounding limitations of these two groups, we do not feel confident one way or another making a conclusion regarding anti-coagulation use and our hypothesized outcome measures with respect to drain usage. Though there are theoretical advantages to the use of a drain, there is little scientific evidence to demonstrate benefits associated with their use. In the present study, the routine use of a wound drain device has been shown to increase overall EBL, LOS, and
Graph 1. Selective drain use by procedure, all surgeons.
P
Aspirin
Warfarin
P
0.17 0.021 0.99 0.028 b 0.0001 0.49
3 0 3 64.7 ± 11.6 33.4 ± 5.4 12.0 ± 0.3 1011 ± 201 3.1 ± 1.4 0
57 28 43 68.5 ± 11.7 30.0 ± 6.1 13.4 ± 1.4 1390 ± 458 3.9 ± 1.0 0.211
0.59 0.35 0.091 0.16 0.19 N/A
transfusion rate. Increased LOS and need for transfusions may be associated with an increased total cost of arthroplasty in a growing field. Despite the relatively low purchasing cost of drains, there may be an increased cost associated with their use. The larger clinical picture with respect to an increased length of stay and need for transfusion may be important components in the orthopedic surgeon’s decision-making process, especially if the surgeon does not see a clinical impact on his or her practice. The impact of drainage devices has been shown retrospectively in this study to have a negative impact on blood loss, allogeneic transfusion rate and hospital stay, which may be associated with a higher total cost of arthroplasty to society. At a high volume center with many surgeons, it does not appear that selective drain usage is being practiced, which may prompt further study into which patients may actually benefit from their use. Conclusion With the cost of modern medical care rising and the dramatically increasing incidence of degenerative joint disease in an aging
Graph 2. Selective drain use by procedure, by surgeons performing over 10 of the specified procedure (more than one per week, average).
B.T. Bjerke-Kroll et al. / The Journal of Arthroplasty 29 (2014) 895–899
population, further studies on the cost-saving measures in arthroplasty should be investigated. This paper suggests that the use of drains increases blood loss, transfusion requirements and overall costs in patients undergoing primary unilateral total hip and total knee arthroplasty. Increased blood loss, need for transfusion, and length of stay are of themselves adverse clinical outcomes, and should not necessarily be eclipsed by concerns for cost-effectiveness. Additional data regarding surgeon’s justification for drain use, including visualized intra-operative bleeding, and patient-specific concern for post-operative bleeding would provide useful information not available in a retrospective analysis. A prospective study would provide useful information on this subject (Graphs 1 and 2) [30,31]. References 1. Murphy L, Helmick CG. The impact of osteoarthritis in the United States: a population-health perspective. Am J Nurs 2012;112(3 Suppl 1):S13. 2. Dillon CF, Rasch EK, Gu Q, et al. Prevalence of knee osteoarthritis in the United States: arthritis data from the Third National Health and Nutrition Examination Survey 1991–94. J Rheumatol 2006;33(11):2271. 3. Kotze A, Carter LA, Scall AJ. Effect of a patient blood management programme on preoperative anaemia, transfusion rate, and outcome after primary hip or knee arthroplasty: a quality improvement cycle. Br J Anaesth 2012;108(6):943. 4. Joy PJ, Bennet SJ. The appropriateness of blood transfusion following primary total hip replacement. Ann R Coll Surg Engl 2012;94(3):201. 5. Verlicchi F, Desalvo F, Zanotti G, et al. Red cell transfusion in orthopaedic surgery: a benchmark study performed combining data from different data sources. Blood Transfus 2011;9(4):383. 6. Shander A, Hofmann A, Ozawa S, et al. Activity-based costs of blood transfusions in surgical patients at four hospitals. Transfusion 2010;50(4):753. 7. Nadler SB, Hidalgo JU, Bloch T. Prediction of blood volume in normal human adults. Surgery 1962;51:224. 8. Good L, Peterson E, Lisander B. Tranexamic acid decreases external blood loss but not hidden blood loss in total knee replacement. Br J Anaesth 2003;90(5):596. 9. The Henry J. Kaiser Foundation. Hospital adjusted expenses per inpatient day. http://www.statehealthfacts.org/comparemaptable.jsp?ind=273&cat=5; 2010. Accessed 2/15/2013. 10. CPI inflation calculator. 11. Healthcare cost and utilization project. http://www.hcup-us.ahrq.gov/reports/ factsandfigures/2009/pdfs/FF_report_2009.pdf. Accessed 2/15/2013. 12. Woolson ST, Wall WW. Autologous blood transfusion after total knee arthroplasty: a randomized, prospective study comparing predonated and postoperative salvage blood. J Arthroplasty 2003;18(3):243. 13. Rao VK, Dyga R, Bartels C, et al. A cost study of postoperative cell salvage in the setting of elective primary hip and knee arthroplasty. Transfusion 2012;52(8):1750.
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14. Canty SJ, Shepard GJ, Ryan WG, et al. Do we practice evidence based medicine with regard to drain usage in knee arthroplasty? Results of a questionnaire of BASK members. Knee 2003;10(4):385. 15. Cheung G, Carmont MR, Bing AJ, et al. No drain, autologous transfusion drain or suction drain? A randomised prospective study in total hip replacement surgery of 168 patients. Acta Orthop Belg 2010;76(5):619. 16. Kumar S, Penematsa S, Parekh S. Are drains required following a routine primary total joint arthroplasty? Int Orthop 2007;31(5):593. 17. Alexander JW, Korelitz J, Alexander NS. Prevention of wound infections. A case for closed suction drainage to remove wound fluids deficient in opsonic proteins. Am J Surg 1976;132(1):59. 18. Omonbude D, El Masry MA, O'Connor PJ, et al. Measurement of joint effusion and haematoma formation by ultrasound in assessing the effectiveness of drains after total knee replacement: a prospective randomised study. J Bone Joint Surg Br 2010;92(1):51. 19. Li C, Nijat A, Askar M. No clear advantage to use of wound drains after unilateral total knee arthroplasty: a prospective randomized, controlled trial. J Arthroplasty 2011;26(4):519. 20. Madadi F, Mehrvarz AS, Madadi F, et al. Comparison of drain clamp after bilateral total knee arthroplasty. J Knee Surg 2010;23(4):215. 21. Tai TW, Jou IM, Chang CW, et al. Non-drainage is better than 4-hour clamping drainage in total knee arthroplasty. Orthopedics 2010;10:156. 22. Zhang QD, Guo WS, Zhang Q, et al. Comparison between closed suction drainage and nondrainage in total knee arthroplasty: a meta-analysis. J Arthroplasty 2011;26(8):1265. 23. Holt BT, Parks NL, Engh GA, et al. Comparison of closed-suction drainage and no drainage after primary total knee arthroplasty. Orthopedics 1997;20(12) 1121,4; discussion 1124-5. 24. Esler CN, Blakeway C, Fiddian NJ. The use of a closed-suction drain in total knee arthroplasty. A prospective, randomised study. J Bone Joint Surg Br 2003;85(2):215. 25. Hazarika S, Bhattacharya R, Bhavikatti M, et al. A comparison of post-op haemoglobin levels and allogeneic blood transfusion rates following total knee arthroplasty without drainage or with reinfusion drains. Acta Orthop Belg 2010;76(1):74. 26. Stucinskas J, Tarasevicius S, Cebatorius A, et al. Conventional drainage versus four hour clamping drainage after total knee arthroplasty in severe osteoarthritis: a prospective, randomised trial. Int Orthop 2009;33(5):1275. 27. Niskanen RO, Korkala OL, Haapala J, et al. Drainage is of no use in primary uncomplicated cemented hip and knee arthroplasty for osteoarthritis: a prospective randomized study. J Arthroplasty 2000;15(5):567. 28. Mirza SB, Campion J, Dixon JH, et al. Efficacy and economics of postoperative blood salvage in patients undergoing elective total hip replacement. Ann R Coll Surg Engl 2007;89(8):777. 29. Munoz M, Ariza D, Campos A, et al. The cost of post-operative shed blood salvage after total knee arthroplasty: an analysis of 1,093 consecutive procedures. Blood Transfus 2012;7:1. 30. Watanabe KK, Williams AE, Schreiber GB, et al. Infectious disease markers in young blood donors. Retrovirus Epidemiology Donor Study. Transfusion 2000;40(8):954. 31. Wales PW, Lau W, Kim PC. Directed blood donation in pediatric general surgery: is it worth it? J Pediatr Surg 2001;36(5):722.
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
The Increased Total Cost Associated With Post-Operative Drains in Total Hip and Knee Arthroplasty Benjamin T. Bjerke-Kroll, MD, MS, Peter K. Sculco, MD, Alexander S. McLawhorn, MD, MBA, Alexander B. Christ, MD, Brian P. Gladnick, MD, David J. Mayman, MD Hospital for Special Surgery, New York, New York
a r t i c l e
i n f o
Article history: Received 4 September 2013 Accepted 30 October 2013 Keywords: cost-effectiveness arthroplasty post-operative suction device blood loss transfusion length of stay
a b s t r a c t In a consecutive series of 536 unilateral primary total hip arthroplasties (THAs) and 598 unilateral primary total knee arthroplasties (TKAs), the use of a post-operative drain was associated with $538 additional cost per THA, and $455 for TKA. The use of a drain increased hospital length of stay (LOS) for THA, but not for TKA. In both groups, the use of a drain increased estimated blood loss (EBL) and increased the amount of allogeneic blood transfused. Over the 10-week period, drain use was associated with a total cost of $432,972 for our institution. Data from this study would favor a selective approach to the use of drains in primary joint arthroplasties. © 2014 Elsevier Inc. All rights reserved.
In the United States, over 900,000 total hip or total knee arthroplasties were performed in 2012 at a cost of $42.3B [1]. Osteoarthritis is the now the most frequent cause of disability in the United States, and over 10% of the US population reports symptomatic osteoarthritis [1,2]. In modern lower extremity arthroplasty, an estimated 7%–53% of these patients will require blood transfusion [3–5], at a cost of $522–$1183 per unit [6]. Any significant decrease in peri-operative transfusion rate or overall cost of arthroplasty will result in major health care cost reduction.
Materials and Methods This study was conducted in a high-volume tertiary-care private teaching hospital in an urban setting. All primary unilateral hip and knee arthroplasties performed during a 10-week period were included, regardless of surgeon, surgeon training or subspecialty,
Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. None of the authors, or their institution(s), have had any financial relationship, in the thirty-six months prior to submission of this work, with any entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. Also, no author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The Conflict of Interest statement associated with this article can be found at http://dx.doi.org/10.1016/j.arth.2013.10.027. Reprint requests: Benjamin T. Bjerke-Kroll, MD, Hospital for Special Surgery, 535 E 70th St, New York, NY 10021. 0883-5403/2905-0007$36.00/0 – see front matter © 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.arth.2013.10.027
anesthetic technique, implant selection, patient demographics, anticoagulation or post-operative protocols. The study received approval by the institutional review board at the authors’ institution. An electronic search of all hospital records was conducted over an arbitrary 10-week period (October 2010 to December 2010). 1341 patients with ICD-9 codes 81.51 (THA) and 81.54 (TKA) were identified. Patients were included if the following information were available: height, weight, pre-operative hemoglobin (Hb) within 30 days of the procedure, Hb values recorded for post-operative days 1 and 2, anticoagulant used, recorded use or non-use of a drain, and drain output, when applicable. Patients were excluded if they received bilateral surgery, hemiarthroplasty, hip resurfacing, unicondylar knee arthroplasty. There were no data collected beyond the initial hospitalization period. Additional exclusion criteria included pre-operative fracture, pre-existing coagulopathy, or any concomitant procedure, including removal of hardware, arthrocentesis, and tenotomy. 536 THAs and 598 TKAs were included in the current study. These were performed by 42 surgeons. THA and TKA data were analyzed separately. Data collected included procedure, gender, date of birth, LOS, surgeon, pre-operative Hb, all available Hb values throughout the hospital stay, amount and type of all blood products transfused throughout the hospital stay, and presence of a drain with any associated output. Radiographs were analyzed if there was a question of procedure performed or presence of pre-existing hardware. Post-operative care and decision-making regarding blood product transfusion, drain removal, and discharge date are managed by attending surgeons, attending medical physicians, resident physicians, and physician assistants. A standardized post-operative transfusion protocol is utilized by the hospital and all housestaff with recommended transfusion thresholds. The recommended transfusion
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threshold for all post-operative patients is Hb b 8.0 dL, unless otherwise specified by the patient’s internist or surgeon. For all surgeons, drains were placed to suction immediately post-operatively, and suction remained in place until removal unless an exceptional amount of drainage was noted, in which case the drain was placed temporarily to gravity. During the study period, drains were routinely removed on the first post-operative day, unless an exceptional output was noted and the drain was left in place for an additional 24 h. Estimated Blood Loss Calculation The following formula, as originally described by Nadler et al [7,8], was used to calculate estimated blood volume (EBV): Males: EBV ¼ 1000
3
0:3669 height
þ ð0:03219 weightÞ; þ0:6041
þ ð0:03308 weightÞ; þ0:1833
Females: EBV ¼ 1000
3
0:3561 height
Height and weight are measured in meters and kilograms, respectively. EBL was estimated using the following formulas [7,8]: Hbloss ¼ EBV ðHbi −Hbe Þ 0:001 þ Hbt EBL ¼ 1000 Hbloss =Hbi
the cost per transfusion, and 3) the cost of the drainage device. The following equation was used to estimate the cost associated with drain use: fðLOSdrain −LOSno drain Þ 2011g þ fðTxdrain −Txno drain Þ 761g þ 35 Where LOS represents average length of hospital stay for each group, $2011 is the cost per day, Tx represents the mean number of transfused units per patient, $761 is the cost per transfusion, and $35 represents the cost of the drain. Drain Use by Surgeon Preference Our study was designed to select for a large cross-section of patients without coagulatopathy. However, certain intra-operative factors may account for a noticeable difference in blood loss or postoperative drainage, and may prompt the operating surgeon to elect for or against the use of a drainage device. Our observation before initiation of the study is that the use of a drain is more surgeondependent, and less dependent on intra-operative events or patient characteristics. For this reason, we performed a secondary analysis of drain usage by surgeon. We considered the surgeon to be “selective” if a drain was placed in 10%–90% of cases for a particular operation, otherwise the surgeon was considered “non-selective”. Statistical Methods
Hbi represents the initial hemoglobin concentration in g/dL, Hbe represents a subsequent hemoglobin concentration, and Hbt represents the amount of Hb transfused in grams. For this study, Hbe was defined as the last Hb recorded during the hospital stay. In order to estimate the amount of Hb per transfusion (Hbt), 25 samples of autologous and 25 samples of allogeneic blood were chosen at random from our blood bank. All were analyzed (ADVIA 120, Siemens AG, Erlangen, Germany) for total volume and Hb density (Hbt = Hb × V). On average, one unit of autologous and allogeneic blood contained 56.3 ± 5.7 g and 58.1 ± 7.9 g of Hb, respectively. There was no significant difference between these blood products, and little variation between samples. Cost Determination The impact of hospital stay on cost was calculated assuming a cost of $2011 per day, as determined by an independent source of healthcare research for all hospital stays [9] and adjusted for 2012 [10]. This estimate is conservative, given the Healthcare Cost and Utilization Project estimate of $2500 per hospital day in 2009 [11]. The total cost of a transfused unit of autologous or allogeneic blood was calculated to be $761 [6]. This is consistent with prior estimates [12,13] The drain device utilized by our institution is the ConstaVac (Stryker, Kalamazoo, MI) and represents a $35 cost per device to the authors’ institution. The total cost associated with drain use will be a sum of the following: 1) the difference in LOS for both groups multiplied by the cost per hospital day, 2) the difference in transfusions multiplied by
A Student’s t test was used to examine statistical significance for all groups individually, as well as overall cost differential. Results There were no significant demographic or pre-operative differences between THA patients who received a drain and those who did not (Table 1). Likewise, there were no demographic or pre-operative differences in the TKA cohort. Of 536 THA patients studied, 62% received a drainage device. Of 598 TKA patients studied, 88% received a drainage device. The use of a drain significantly increased LOS for THA (3.52 ± 1.1 days vs 3.30 ± 0.8, P b 0.01) but not for TKA (4.01 ± 1.2 days vs 3.93 ± 1.0, P N 0.05) (Tables 2 and 3). In both groups, the use of a drain significantly increased EBL (THA: 1298 mL vs 1215, P b 0.05; TKA: 1575 vs 1375, P b 0.001). The drain group received a significantly increased amount of allogeneic blood transfused (THA: 0.24 vs 0.16 U, P b 0.05; TKA: 0.54 vs 0.20 U, P b 0.05). The additional cost per patient associated with drain use was $538 for THA and $455 for TKA (Table 4). Over the 10-week period of investigation in our hospital, the total associated cost for drains was: TKA: $538 × 524 = $281,912 THA: $455 × 332 = $151,060 Total cost: $432,972 All drains in this study period were removed by the second postoperative day.
Table 1 Comparison of Groups by Procedure and Drain Selection. Patient Characteristics N Male:Female Age (year) Weight (kg) BMI (kg/m2) Pre-ob Hb (g/dL)
THA Drain 332 146:185 65.8 ± 11.0 81.3 ± 19.1 28.3 ± 5.6 13.6 ± 1.3
TKA No Drain 204 93:101 66.4 ± 79.4 ± 27.6 ± 13.5 ±
10.7 19.5 5.5 1.4
P
Drain
0.28 0.14 0.092 0.14
524 226:298 68.2 ± 9.9 86.9 ± 19.1 30.7 ± 6.0 13.3 ± 1.5
No Drain 74 28:46 69.3 ± 84.8 ± 30.1 ± 13.3 ±
9.2 15.9 6.1 1.4
P
0.055 0.15 0.22 0.49
B.T. Bjerke-Kroll et al. / The Journal of Arthroplasty 29 (2014) 895–899 Table 2 Comparison of THA Outcome Measures by Drain Use.
n LOS (days) EBL (mL) Homologous Transfusion (U)
Table 4 Analysis of Drain Usage by Surgeon.
Drain
No Drain
332 3.52 ± 1.1 1298 ± 449 0.24
204 3.30 ± 0.8 1215 ± 429 0.16
P 0.004 0.017 0.047
The average total recorded drain output was 245 ± 207 mL for THA, and 623 ± 296 mL for TKA. All patients received aspirin (325 mg orally twice per day) or warfarin (based on INR) during the immediate post-operative hospitalization period; there were no other types of pharmacologic anti-coagulation used in this patient population during the study period. When drain usage and procedures were controlled for, the warfarin group was consistently older (although significant for only one group) and had a higher BMI (significant for two groups, excluding TKAs without a drain due to the low number of patients). For the warfarin group, EBL was higher in all groups (significantly in one) and LOS was longer (significant in three of four groups). No difference in transfusion rate could be found between groups. All data are listed in Tables 5 and 6. No patient received reinfusion from the drainage device. THAs were performed by 42 different surgeons, and TKAs were performed by 25 different surgeons during the study period. For TKAs, 83.3% (35/42) of surgeons utilized a drain in 0% or 100% of their cases, and 4.7% (2/42) of surgeons were “selective”. For THAs, 52.0% (13/25) of surgeons utilized a drain in 0% or 100% of patients, and 12.0% (3/25) of surgeons were “selective”. Discussion The use of wound drains after arthroplasty surgery has been controversial [14–16]. Arguments for drain devices include a theoretical decreased risk of surgical site infection [17] and decreased hematoma formation, which may limit range of motion. Others argue that drains do not affect range of motion, serve as a portal for infection, increase post-operative blood loss and need for transfusion. Empirically, drains have been shown to decrease the size of postoperative effusion [18] but not affect TKA range of motion [19–22], decrease ecchymosis [23], increase peri-operative blood loss [24–26], and increase the need for blood transfusion postoperatively [15,19,25,26]. They have been shown to have no effect on wound healing [27], deep venous thrombosis [22] or postoperative infection rate [22]. At our institution, drain use in primary lower extremity arthroplasty over a 10-week period was associated at a cost of over $400,000. If a measurable benefit can be shown from future studies with drain use, these data may provide a baseline for costeffectiveness. To our knowledge, this is the first study that investigated the costs associated with drain use after total joint arthroplasty. Drains have been shown to be cost-effective when used with a post-operative reinfusion protocol for both THA [28] and TKA [29]. However, in the absence of reinfusion, the use of a drainage device has not been studied with regard to cost.
Table 3 Comparison of TKA Outcome Measures by Drain Use.
N LOS EBL (mL) Homologous Transfusion (U)
897
Drain
No Drain
P
524 4.01 ± 1.2 1575 ± 496 0.54
74 3.93 ± 1.0 1375 ± 456 0.20
0.113 0.0004 0.036
TKA
THA
Surgeon
Drain
None
% Drain
Drain
None
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42
0 5 29 24 4 6 1 2 1 19 1 10 43 1 2 76 2 4 2 11 21 5 16 7 12 26 9 13 14 15 3 3 18 4 15 26 5 0 8 23 7 31
12 0 2 0 0 0 37 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 1 2 0 0 0 0 0 0 0 16 0 0 1 0
0% 100% 94% 100% 100% 100% 3% 100% 100% 100% 100% 100% 96% 100% 100% 100% 100% 100% 100% 100% 100% 100% 94% 100% 100% 100% 100% 100% 93% 88% 100% 100% 100% 100% 100% 100% 100% 0% 100% 100% 88% 100%
2 0 5 1 14 0 30 0 0 30 0 0 2 0 0 2 0 1 0 0 12 4 22 0 29 10 0 4 30 19 1 0 9 1 50 29 0 2 0 20 0 3
22 0 35 32 0 0 0 0 0 0 0 0 15 0 0 0 0 0 0 0 11 1 0 0 0 6 0 56 0 1 0 0 0 0 1 1 0 22 0 0 0 0
% Drain 8% – 13% 3% 100% – 100% – – 100% – – 12% – – 100% – 100% – – 52% 80% 100% – 100% 63% – 7% 100% 95% 100% – 100% 100% 98% 97% – 8% – 100% – 100%
Surgeons in bold performed over 10 of the specified procedure.
This current study suggests that the use of wound drains is associated with a significant increase in cost during a patient’s hospital stay for primary unilateral knee and hip arthroplasty. A secondary analysis of these data has shown use of a wound drain to increase postoperative blood loss and transfusion requirements for both procedures, while length of hospital stay was significantly increased for THA. The current study has several limitations. It investigates a large and relatively unfiltered data set and therefore could be biased. However, it does therefore give an overview over a variety of different surgical techniques and is more representative of overall care and cost at a large orthopedic specialty hospital. One advantage of this study is the large number of patients collected in a short period of time. Changes in treatment protocols and surgical technique are unlikely to change significantly over a 10-week period. One limitation of a retrospective review is that we do not know the individual justification for use of a drain for each patient. A possible confounding association in this study is a more noticeable appearance of intra-operative bleeding may prompt the surgeon to place a drain that otherwise would not; similarly a “dry” surgical field may cause the surgeon to forgo the use of a drain. It is our impression that this is the exception, and that most surgeons place a drain based on convention, rather than intra-operative appearance. Our review of drain use by surgeon supports this for most surgeons; the majority of surgeons use a drain in less than 10% or over 90% of cases.
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Table 5 Comparison of THAs by Drain Usage and Anti-Coagulation. Drain
n Male Female Age BMI Pre-ob Hb EBL LOS Transfusions
No Drain
Aspirin
Warfarin
246 103 143 65.8 ± 10.5 27.7 ± 5.2 13.6 ± 1.3 1289 ± 440 3.4 ± 1.0 0.2
86 44 42 68.3 ± 11.3 29.8 ± 6.8 13.7 ± 2.0 1351 ± 488 3.9 ± 1.3 0.36
P
Aspirin
0.063 0.033 0.6 0.28 0.0003 0.093
147 70 77 65.0 ± 27.4 ± 13.6 ± 1190 ± 3.2 ± 0.16
Warfarin 57 23 34 67.1 ± 28.0 ± 13.1 ± 1282 ± 3.5 ± 0.14
10.6 5.4 1.3 417 0.7
12.5 5.9 1.5 457 0.8
P
b 0.0001 0.49 0.019 0.17 0.009 0.26
Table 6 Comparison of TKAs by Drain Usage and Anti-Coagulation. Drain
n Male Female Age BMI Pre-ob Hb EBL LOS Transfusions
No Drain
Aspirin
Warfarin
46 19 27 65.8 ± 10.5 28.8 ± 4.6 13.3 ± 1.9 1422 ± 582 3.7 ± 1.0 0.46
478 207 271 68.0 ± 10.3 30.9 ± 6.0 13.3 ± 1.4 1590 ± 485 4.5 ± 0.7 0.33
It is important to translate the data to clinical application in our study: blood cannot be transfused in a fraction of a unit, nor can a patient be hospitalized for a fraction of a day with a meaningful significance with regard to cost. A more meaningful measure may be to discuss our findings with regard to 100 patients. For example, stating that drain use with TKA increased the rate of transfusion from 20 U to 54 U per 100 arthroplasties; drain use with THA increased the rate of transfusion from 16 U to 24 U per 100 arthroplasties. Anti-coagulation use was recorded to investigate a possible correlation with post-operative blood loss. As we suspected, warfarin use is a predictor of higher BMI and older age, which may be accounted for in their inherent increased risk of thrombus and/or embolism. Nonetheless, there did not appear to be differences in overall transfusion rate. Because of the confounding limitations of these two groups, we do not feel confident one way or another making a conclusion regarding anti-coagulation use and our hypothesized outcome measures with respect to drain usage. Though there are theoretical advantages to the use of a drain, there is little scientific evidence to demonstrate benefits associated with their use. In the present study, the routine use of a wound drain device has been shown to increase overall EBL, LOS, and
Graph 1. Selective drain use by procedure, all surgeons.
P
Aspirin
Warfarin
P
0.17 0.021 0.99 0.028 b 0.0001 0.49
3 0 3 64.7 ± 11.6 33.4 ± 5.4 12.0 ± 0.3 1011 ± 201 3.1 ± 1.4 0
57 28 43 68.5 ± 11.7 30.0 ± 6.1 13.4 ± 1.4 1390 ± 458 3.9 ± 1.0 0.211
0.59 0.35 0.091 0.16 0.19 N/A
transfusion rate. Increased LOS and need for transfusions may be associated with an increased total cost of arthroplasty in a growing field. Despite the relatively low purchasing cost of drains, there may be an increased cost associated with their use. The larger clinical picture with respect to an increased length of stay and need for transfusion may be important components in the orthopedic surgeon’s decision-making process, especially if the surgeon does not see a clinical impact on his or her practice. The impact of drainage devices has been shown retrospectively in this study to have a negative impact on blood loss, allogeneic transfusion rate and hospital stay, which may be associated with a higher total cost of arthroplasty to society. At a high volume center with many surgeons, it does not appear that selective drain usage is being practiced, which may prompt further study into which patients may actually benefit from their use. Conclusion With the cost of modern medical care rising and the dramatically increasing incidence of degenerative joint disease in an aging
Graph 2. Selective drain use by procedure, by surgeons performing over 10 of the specified procedure (more than one per week, average).
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population, further studies on the cost-saving measures in arthroplasty should be investigated. This paper suggests that the use of drains increases blood loss, transfusion requirements and overall costs in patients undergoing primary unilateral total hip and total knee arthroplasty. Increased blood loss, need for transfusion, and length of stay are of themselves adverse clinical outcomes, and should not necessarily be eclipsed by concerns for cost-effectiveness. Additional data regarding surgeon’s justification for drain use, including visualized intra-operative bleeding, and patient-specific concern for post-operative bleeding would provide useful information not available in a retrospective analysis. A prospective study would provide useful information on this subject (Graphs 1 and 2) [30,31]. References 1. Murphy L, Helmick CG. The impact of osteoarthritis in the United States: a population-health perspective. Am J Nurs 2012;112(3 Suppl 1):S13. 2. Dillon CF, Rasch EK, Gu Q, et al. Prevalence of knee osteoarthritis in the United States: arthritis data from the Third National Health and Nutrition Examination Survey 1991–94. J Rheumatol 2006;33(11):2271. 3. Kotze A, Carter LA, Scall AJ. Effect of a patient blood management programme on preoperative anaemia, transfusion rate, and outcome after primary hip or knee arthroplasty: a quality improvement cycle. Br J Anaesth 2012;108(6):943. 4. Joy PJ, Bennet SJ. The appropriateness of blood transfusion following primary total hip replacement. Ann R Coll Surg Engl 2012;94(3):201. 5. Verlicchi F, Desalvo F, Zanotti G, et al. Red cell transfusion in orthopaedic surgery: a benchmark study performed combining data from different data sources. Blood Transfus 2011;9(4):383. 6. Shander A, Hofmann A, Ozawa S, et al. Activity-based costs of blood transfusions in surgical patients at four hospitals. Transfusion 2010;50(4):753. 7. Nadler SB, Hidalgo JU, Bloch T. Prediction of blood volume in normal human adults. Surgery 1962;51:224. 8. Good L, Peterson E, Lisander B. Tranexamic acid decreases external blood loss but not hidden blood loss in total knee replacement. Br J Anaesth 2003;90(5):596. 9. The Henry J. Kaiser Foundation. Hospital adjusted expenses per inpatient day. http://www.statehealthfacts.org/comparemaptable.jsp?ind=273&cat=5; 2010. Accessed 2/15/2013. 10. CPI inflation calculator. 11. Healthcare cost and utilization project. http://www.hcup-us.ahrq.gov/reports/ factsandfigures/2009/pdfs/FF_report_2009.pdf. Accessed 2/15/2013. 12. Woolson ST, Wall WW. Autologous blood transfusion after total knee arthroplasty: a randomized, prospective study comparing predonated and postoperative salvage blood. J Arthroplasty 2003;18(3):243. 13. Rao VK, Dyga R, Bartels C, et al. A cost study of postoperative cell salvage in the setting of elective primary hip and knee arthroplasty. Transfusion 2012;52(8):1750.
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