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Comparing the Incidence and Clinical Data for Simultaneous Bilateral Versus Unilateral Total Hip Arthroplasty in New York State Between 1990 and 2010
The Journal of Arthroplasty xxx (2015) xxx–xxx
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Comparing the Incidence and Clinical Data for Simultaneous Bilateral Versus Unilateral Total Hip Arthroplasty in New York State Between 1990 and 2010 Sergio A. Glait, MD , Omar N. Khatib, MD, Ankit Bansal, MD, Jason P. Hochfelder, MD, James D. Slover, MD Department of Orthopaedic Surgery, NYU Langone Medical Center Hospital for Joint Diseases, New York, New York
a r t i c l e
i n f o
Article history: Received 14 May 2014 Accepted 21 May 2015 Available online xxxx Keywords: bilateral hip arthroplasty incidence complications epidemiology
a b s t r a c t A New York State database reported information on all total hip arthroplasty cases between 1990 and 2010 comparing unilateral (242,588 cases) to simultaneous bilateral (4538 cases) procedures. Our data showed that the population incidence of this surgery increased 120.2% over twenty years, yet the proportionate number of simultaneous cases has decreased. Simultaneous procedures were found to occur more commonly in younger patients with private insurance. In addition, bilateral procedures showed an increase in PE, DVT, length of stay, and discharge to rehab facilities; whereas mortality and blood transfusions compared to unilateral procedures showed no difference. © 2015 Elsevier Inc. All rights reserved.
In the United States, total hip arthroplasty has become an increasingly sought after operation to improve a patient’s function from osteoarthritis of the hip. Projections have demonstrated that by the year 2030 the demand for primary total hip arthroplasty is estimated to grow to 572,000 cases per year [1]. Increases in life expectancy and a growing active elderly population from the baby-boom era will cause the demand for hip arthroplasty procedures to continue to rise over the coming years. For patients with bilateral disease, a decision about performing the procedures simultaneously or staged by some interval must be made by the surgeon and patient. Simultaneous bilateral THA has been performed since the 1970s and it has been a repeated topic examined in the orthopaedic literature [2–4]. Many surgeons fear that performing a bilateral procedure puts the patient at increased risk of complications, and some studies have supported this idea [5]. However, other studies have shown that simultaneous bilateral THA is effective in relieving pain and improving function without significantly increasing perioperative complications [6–10]. In addition, it may be cost-effective to perform simultaneous procedures where appropriate in a single hospital admission. It is estimated that 60% of hip arthroplasty procedures are paid by the government under the Centers for Medicare and Medicaid Services (CMS) [1]. In 1992, Medicare reimbursement for a second total joint
One or more of the authors of this paper have disclosed potential or pertinent conflicts of interest, which may include receipt of payment, either direct or indirect, institutional support, or association with an entity in the biomedical field which may be perceived to have potential conflict of interest with this work. For full disclosure statements refer to http://dx.doi.org/10.1016/j.arth.2015.05.046. Reprint requests: Sergio A. Glait, MD, 301 E 17th street, 14 flr, New York, NY 10003.
arthroplasty decreased 50% if performed within 90 days of the first procedure [11]. Physician reimbursement has decreased 39% between 1991 and 2006 [12]. In addition, the need to decrease healthcare spending, particularly on total joint arthroplasty procedures, has become an issue of paramount concern. The performance of simultaneous bilateral THA may be one way to do this through the elimination of an extra hospitalization by not staging the procedure. This study aims to compare the incidence and complications of simultaneous THA to unilateral THA over the past 20 years in New York State with the hypothesis that the incidence of simultaneous THA procedures has changed over time and that this procedure results in more complications compared to unilateral THA procedures.
Materials and Methods The Statewide Planning and Research Cooperative System (SPARCS) database from the New York State Department of Health was established in 1979 to record all inpatient hospital admissions under Public Health Law. Since then, SPARCS has streamlined this collection process in accordance with the Universal Data Set specifications. Previously published studies have used the SPARCS database to report epidemiologic data for various diseases and operative procedures [13–15]. The de-identified patient database was utilized to review all unilateral and simultaneous bilateral total hip arthroplasty procedures performed between 1990 and 2010 during a single hospital admission. The SPARCS inpatient registry was queried for ICD-9-CM v3 code 81.51 “Total Hip Arthroplasty (THA)”. Hospital admissions with only one code 81.51 were recorded as unilateral procedures, and admissions with two codes
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Please cite this article as: Glait SA, et al, Comparing the Incidence and Clinical Data for Simultaneous Bilateral Versus Unilateral Total Hip Arthroplasty in New York State Be..., J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.05.046
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S.A. Glait et al. / The Journal of Arthroplasty xxx (2015) xxx–xxx
of 81.51 were recorded as simultaneous bilateral THA. This methodology has been previously published in peer-reviewed journals [16]. To minimize the likelihood of attaining skewed demographical results, cases where patient age was not properly recorded were also excluded from analysis (346 cases, 0.001% of dataset). The obtained data were adjusted for differences in population size, as reported by the New York State Census database. Trends in incidence and demographics of unilateral and simultaneous bilateral THA were reviewed along with insurance status, primary diagnoses, hospital length of stay, disposition (home vs. rehabilitation), blood transfusions, and complications including mortality, deep vein thrombosis (DVT) and pulmonary embolism (PE). Charlson comorbidity scores were calculated for every patient using methods described by Charlson et al with scoring based on ICD-9 codes as outlined by Deyon et al whereby points were assigned for various co-morbidities such as myocardial infarction, congestive heart failure, peripheral vascular disease [17,18]. Secondary analyses of the effect of surgical volume were performed based on a high and low volume group. The high volume group was defined as all surgeons who performed the upper 50% of all procedures (i.e. for all simultaneous bilateral THA procedures the high volume group is composed of all surgeons who performed 50% of all procedures). The low volume group was defined as the remaining group of surgeons not in the high volume group (i.e. lower 50% of procedures). The data were stratified into two time periods to analyze trends with respect to time, with time period 1 defined as 1990–1999 and time period 2 defined as 2000–2010. SAS v9.3 (SAS institute, Cary, NC) was used for all data processing and statistical analyses. A paired Student t-test was used to compare findings between group 1 (unilateral THA) and group 2 (simultaneous bilateral THA) for continuous variables. A chi-squared test was used to compare categorical analyses with statistical significance set a priori at the .05 level. Results Between 1990 and 2010 there was a total number of 4538 simultaneous bilateral total hip arthroplasty procedures performed compared to 242,588 unilateral total hip arthroplasty procedures in New York State. In 1990–1999, there were 1768 simultaneous bilateral procedures compared to 86,144 unilateral THA procedures. In 2000–2010, there were 2770 simultaneous bilateral procedures compared to 156,444 unilateral THA procedures. A summary of patient demographic data from the SPARCs database is shown in Table 1. Demographic data comparing these two procedures demonstrate that more males had a simultaneous bilateral THA procedure compared to females (51.2% versus 48.8%; P b 0.05) between the years 1990 and 2010. However, women did have this procedure performed more frequently than men between the years of 1990 and 1999 (52.1% versus 47.9%). The average age of patients receiving a simultaneous bilateral THA procedure was significantly younger than those receiving unilateral procedures (56.7 years versus 65.9 years; P b 0.05). Lastly, a statistically higher percentage of patients with simultaneous bilateral THA had private insurance (66.6%) compared to a federally based insurance plan (33.4%). This trend was consistently seen between the two time periods studied with an increase in the number of patients with private versus federal insurance (72.1% versus 27.9%) having a simultaneous THA procedure in the latter half of the study period (2000–2010). Since 1990 the population-adjusted incidence (cases per 100,000) of total hip arthroplasty procedures has steadily increased 120.2% from 40.6 to 89.4 cases (Fig. 1). Fig. 2 shows the percent incidence of simultaneous bilateral THA, which decreased from 2.28% in 1990 to 1.51% in 2010. Table 2 demonstrates a summary of clinical data collected from the SPARCS database. Between 1990 and 1999 the average length of stay for a simultaneous bilateral THA was 12.75 ± 5.15 days compared to 9.33 ± 3.22 days for a unilateral THA (P b 0.05). This was reduced significantly between 2000 and 2010 to 5.92 ± 0.56 and 4.53 ± 0.42 days respectively for bilateral and unilateral THA procedures
Table 1 Patient Demographic Data Between 1990 and 2010. Bilateral THA
Unilateral THA
P Value
Demographics Female Patients (%) 1990–1999 2000–2010 Male Patients (%) 1990–1999 2000–2010 Patient Age (mean) 1990–1999 2000–2010
48.8 52.1 46.8 51.2 47.9 53.2 56.7 ± 13.4 59.5 56.3
57.9 59.3 57.1 42.1 40.7 42.9 65.9 ± 13.0 70.4 65.6
b0.00001 b0.00001 b0.00001 b0.00001 b0.00001 b0.00001 b0.00001 b0.00001 b0.00001
Primary Diagnosis Osteoarthritis (%) Femur Fracture (%) Aseptic Necrosis (%) RA, Infl Arthritis (%) Hip Dysplasia (%)
80 0.8 7.4 6.7 0.5
78.5 5.4 4.4 3.6 0.2
n/a n/a n/a n/a n/a
Insurance Federal Insurance (%) 1990–1999 2000–2010 Private Insurance (%) 1990–1999 2000–2010
33.4 42.6 27.9 66.6 57.4 72.1
53.1 63.2 48 46.9 36.8 52
b0.00001 b0.00001 b0.00001 b0.00001 b0.00001 b0.00001
Percentages based on 4538 bilateral (1768 cases in 1990–99 and 2770 cases in 2000–2010) and 242,588 unilateral (86,144 cases in 1990–99 and 156,444 cases in 2000–2010) procedures. Federal insurance includes Medicare, Medicaid, CHAMPUS, and other federal programs. Private insurance includes workers compensation, self-pay, and other non-federal insurance programs.
(P b 0.05). However, the cumulative length of stay between 2000 and 2010 shows a significantly reduced length of stay for simultaneous bilateral THA compared to unilateral procedures (5.92 vs. 9.06 days; P b 0.05). Disposition of patients was analyzed as being discharged either to home or to a rehabilitation service. When comparing all years studied, significantly more unilateral THA procedures were discharged home (51.69%) compared with simultaneous bilateral THA procedures (34.51%). This trend remained consistent when looking at the two different time periods. There was no statistically significant difference in non-cumulative mortality rates between simultaneous bilateral and unilateral THA procedures (0.2% and 0.4% respectively; P N 0.05). However, when examining the different time periods for mortality there was a significant increase in mortality with unilateral THA procedures (0.72%) compared to simultaneous bilateral THA (0.23%) between the years of 1990 and 1999. There is a statistically significant increase of non-cumulative rates of DVT (2.16% versus 0.84%; P b 0.05) and PE (0.79% versus 0.37%; P b 0.05) when comparing simultaneous bilateral THA procedures to unilateral THA. These increased trends are also consistent when looking at the two time periods as well. Cumulative rates of simultaneous bilateral THA and unilateral THA show similar but higher rates of DVT (2.16% and 1.68%; P = 0.0099) and PE (0.79% and 0.74%; P = 0.66) for the bilateral THA group in all years studied. Charlson co-morbidity scores were grouped as being a score of either zero or greater than one. Simultaneous bilateral THA patients were healthier at baseline (score = 0; 77.5%) versus unilateral THA patients (score = 0; 69.8%) based on the Charlson co-morbidity index. In addition, looking at blood transfusion data between groups showed that overall 92% of unilateral THA and 95% of simultaneous bilateral procedures did not receive a blood transfusion. In those patients that did receive a blood transfusion there was no significant difference between the bilateral and unilateral THA groups (4.1 units versus 3 units respectively; P = 0.24). Lastly, clinical data were grouped in terms of surgical volume as described in the materials and methods section (Table 3). For all years
Please cite this article as: Glait SA, et al, Comparing the Incidence and Clinical Data for Simultaneous Bilateral Versus Unilateral Total Hip Arthroplasty in New York State Be..., J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.05.046
S.A. Glait et al. / The Journal of Arthroplasty xxx (2015) xxx–xxx
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Populated-Adjusted Incidence of all THA 100.0 90.0 80.0
Cases per 100,000
70.0 60.0 50.0 40.0 30.0 20.0 10.0 0.0
Fig. 1. Population-adjusted incidence of all total hip arthroplasty procedures performed in New York State.
(1990–2010) there were 12 surgeons that performed 50% of all simultaneous bilateral THA procedures compared to 389 surgeons that were in the lower 50% group for the same procedure. The threshold case volume for the top 12 surgeons in the upper 50-percentile simultaneous bilateral group was a minimum of 90 cases between 1990 and 2010. This threshold value varied between time periods. Between 1990 and 1999 only 7 surgeons made up the top 50% group with a minimum of 56 cases (top surgeon with 205) while 12 surgeons made up the group between 2000 and 2010 with a minimum of 60 cases (top surgeon with 235). Similarly, there were 121 surgeons that performed 50% of all unilateral THA procedures compared to 5849 surgeons in the lower 50% group for the same procedure. The threshold case volume for the top 121 surgeons in the upper 50-percentile unilateral group was a
minimum of 490 cases between 1990 and 2010. Splitting this up between time periods showed that in 1990–1999 121 surgeons made up the top 50% group with a minimum of 167 cases (top surgeon with 2864) while 95 surgeons made up the upper group between 2000 and 2010 with a minimum of 400 cases (top surgeon with 3304). Data showing the number of surgeons in each time period are also shown in Table 3. The high volume surgeon group showed better clinical data when compared to the low volume group as shown in Table 3. Blood transfusions were significantly lower in the high volume group compared to the low volume group for simultaneous bilateral THA (2.16% vs. 7.36%; P b 0.0001). Similarly, blood transfusions were significantly lower in the high volume group compared to the low volume group for unilateral
Percent of Bilateral THA Cases 2.50%
% of all THA cases
2.00%
1.50%
1.00%
0.50%
0.00% 1990
1992
1994
1996
1998
2000
2002
2004
2006
2008
2010
Year Fig. 2. Percent incidence of simultaneous bilateral total hip arthroplasty procedures performed in New York State.
Please cite this article as: Glait SA, et al, Comparing the Incidence and Clinical Data for Simultaneous Bilateral Versus Unilateral Total Hip Arthroplasty in New York State Be..., J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.05.046
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S.A. Glait et al. / The Journal of Arthroplasty xxx (2015) xxx–xxx
Table 2 Clinical Data Collected Between 1990 and 2010.
Length of Stay a 1990–1999 (days) 2000–2010 (days)
Bilateral THA
Unilateral THA
P Value
12.75 5.92
9.33 4.53
b0.0001 b0.0001
Disposition Home 1990–1999 (%) Rehab 1990–1999 (%) Home 2000–2010 (%) Rehab 2000–2010 (%) Home All Years (%) Rehab All Years (%)
58.52 41.48 19.22 80.78 34.51 65.49
69.30 30.70 42.12 57.88 51.69 48.31
Complications a Mortality all years (%) 1990–1999 2000–2010 DVT all years (%) 1990–1999 2000–2010 PE all years (%) 1990–1999 2000–2010
0.2 0.23 0.22 2.16 3.45 1.34 0.79 0.85 0.76
0.4 0.72 0.23 0.84 1.21 0.64 0.37 0.44 0.32
0.059 0.015 0.89 b0.000001 b0.001 b0.001 b0.000001 0.01 b0.001
Charlson Co-Morbidity Score N 1 (%) Score = 0 (%)
22.5 77.5
30.2 69.8
b0.0001 b0.0001
b0.001 b0.001 b0.001
Percentages based on 4538 bilateral (1768 cases in 1990–99 and 2770 cases in 2000–2010) and 242,588 unilateral (86,144 cases in 1990–99 and 156,444 cases in 2000–2010) procedures. Charlson comorbidity scores represent data between all years studied. a Non-cumulative values.
THA (6.54% vs. 8.42%; P b 0.0001). These trends were also consistent between both time periods examined as shown in Table 3. When analyzing disposition based on surgical volume it was found that high volume surgeons discharge a significantly higher number of patients home compared to the low volume group when looking at both simultaneous bilateral THA (37.9% versus 31.1%; P b 0.0001) and unilateral THA groups (52.5% versus 50.9%; P b 0.0001). Differences between time periods can be seen in Table 3. Interestingly, there was no significant difference in simultaneous bilateral THA in terms of discharge home between the high volume and low volume surgeons between the years of 2000 and 2010. Mortality was also analyzed based on surgical volume. When looking at all years (1990–2010) it was found that high volume surgeons had significantly lower mortality rates than low volume surgeons in both the simultaneous bilateral THA (0.04% versus 0.4%; P b 0.0001) and unilateral THA groups (0.12% versus 0.68%; P b 0.0001). This significant trend was also seen in the different time periods except between 2000 and 2010 for the simultaneous bilateral THA group. Discussion Our study aimed to compare the incidence and complications of simultaneous THA to unilateral THA procedures over the past 20 years in New York State with the hypothesis that simultaneous bilateral procedures are decreasing in frequency and have higher complication rates. Orthopaedic surgeons in New York State are performing less simultaneous bilateral THA procedures despite the increasing incidence of total hip arthroplasty. Male patients with private insurance who are young and healthy are the majority having a simultaneous bilateral THA done. When looking at simultaneous bilateral THA patients, DVT and PE occur significantly more, whereas mortality and blood transfusions are not significantly increased. In addition, more patients in this group are discharged to rehab facilities. Lastly, surgeons who perform a majority of these procedures have better outcomes in their patients. There are several possible explanations for the trend of reduced simultaneous bilateral total hip arthroplasties in New York State. From a
Table 3 Percentages Based on 4538 Bilateral (1768 Cases in 1990–99 and 2770 Cases in 2000–2010) and 242,588 Unilateral (86,144 Cases in 1990–99 and 156,444 cases in 2000–2010) Procedures.
# of Surgeons/Cases Threshold a Upper 50% of procedures (all) 1990–1999 2000–2010 Lower 50% of procedures (all) 1990–1999 2000–2010 Clinical Data Blood Transfusions (%) High Volume (all years) 1990–1999 2000–2010 Low Volume (all years) 1990–1999 2000–2010 Disposition (% Going Home) High Volume (all years) 1990–1999 2000–2010 Low Volume (all years) 1990–1999 2000–2010 b Mortality (%) High Volume (all years) 1990–1999 2000–2010 Low Volume (all years) 1990–1999 2000–2010
Bilateral THA
Unilateral THA
12/90 7/56 12/60 389 242 228
121/490 121/167 95/400 5849 3177 3822
2.16 1.14 2.84 7.36 7.86 6.94
6.54 7.96 4.97 8.42 10.51 8.04
37.89 64.3 19.26 31.12 52.8 19.18
52.5 70.37 46.64 50.9 68.23 37.62
0.04 0 0.07 0.4 0.46 0.36
0.12 0.28 0.08 0.68 1.15 0.38
Blood transfusion data are based on whether a patient did or did not receive a blood transfusion and does not relate to the number of units given. All values are statistically significant when comparing high versus low volume in a given category except for those values that are bolded and italicized. a Data are categorized based on the number of high volume (surgeons performing upper 50% of the surgical volume for a given procedure) and low volume (surgeons performing the lower 50% of the surgical volume for a given procedure) surgeons. Case threshold represents the minimum number of cases performed to be included in the top 50% group. b Non-cumulative values.
patient safety perspective, our study showed that there is no significant increase in mortality when comparing non-cumulative rates of simultaneous bilateral versus unilateral THA procedures within the 20-year period. Interestingly, mortality did show an increase in the unilateral group compared to the simultaneous bilateral group between the years of 1990 and 1999 but the reason for this is not known. One plausible explanation for this finding can be that prophylaxis for thromboembolism was less standardized in the early 1990s coupled with the fact that the unilateral group as a whole was older with more comorbidities as evidenced by our Charlson co-morbidity index seen in Table 1. This may have led to a higher mortality in the unilateral THA group. On the other hand, surgeons who perform the majority of these procedures (top 50% in terms of procedures performed) have a significantly decreased mortality rate compared to surgeons on the lower half of the volume curve as evidenced by our data in Table 3. Although we do not know which of these surgeons are fellowship trained, one can assume that the more specialized surgeons at high volume centers who perform the majority of arthroplasty procedures in New York State have less complication rates. Our data are also consistent with previous literature that demonstrated a higher risk of deep vein thrombosis and pulmonary embolism with simultaneous bilateral arthroplasty procedures [5]. These higher rates of PE and DVT are also evident when cumulative rates are taken into account. This may be a major reason surgeons are choosing simultaneous procedures less frequently, and also explains the lower average age of these patients having bilateral procedures (56.7 versus 65.9 years old). Blood transfusions on the other hand were not found to be
Please cite this article as: Glait SA, et al, Comparing the Incidence and Clinical Data for Simultaneous Bilateral Versus Unilateral Total Hip Arthroplasty in New York State Be..., J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.05.046
S.A. Glait et al. / The Journal of Arthroplasty xxx (2015) xxx–xxx
significantly different between groups when looking at the overall 20 year data, however low volume surgeons did show a significant increase in transfusions compared to high volume surgeons. There are costs associated with an increase in venous thromboembolism as well as blood transfusions and this is another reason that surgeons maybe turning away from simultaneous bilateral THA in order to avoid both the added risk to the patient as well as increased hospital costs in a time when hospitals are trying to be cost-effective. Surgeons may have shifted away from performing more simultaneous bilateral THA procedures due to financial influences as well. Reimbursements for a second total joint arthroplasty if performed within 90 days are decreased compared to staging the procedure so that the second surgery is 90 days after the first [11]. Studies have shown that a 30-day episode of care for a bilateral total joint arthroplasty is less expensive overall ($43,600) compared to doubling the same expense for a unilateral total joint without any complications ($25,568) [19]. Perhaps with the changing healthcare system and an increased emphasis on cost savings, surgeons may increase the number of simultaneous bilateral THA procedures in the right patients that minimize the risks. New reimbursement models such as the bundled payment system that proposes to set a fixed payment for an entire episode of care (i.e. 90 days of charges for a total joint arthroplasty) may also have an impact. With bundled payment however, there is more of an incentive to quickly discharge patients home rather than sending them to a rehab facility and our data show that simultaneous bilateral THA patients go to rehab at significantly high rates and have longer hospital lengths of stay compared to the unilateral counterparts (34.5% versus 51.7% of patients as shown in Table 2). At this time, surgeons are choosing simultaneous procedures less frequently despite potential cost savings to the healthcare system, and it is unclear if this trend will change unless more studies can show that it is truly cost-effective in the right patient. This study has both strengths and limitations. One of its strengths includes the statewide data collection regarding total hip arthroplasty procedures over a twenty year period. This provided the authors with a large sample population that helps make accurate calculations and draw conclusions. However, this methodology has its flaws as well since the SPARCS database does not easily provide follow-up on patients. Our data are derived based on a single hospital admission for a given ICD-9 procedural code and therefore we cannot assess the readmission rates or complications that occur post-discharge. Knowing both of these data would add a significant difference to the cost for an entire episode of care and may help answer the question as to whether a simultaneous THA procedure is economically sound, however the study’s aim was not to perform a cost–benefit analysis. In addition, because our data are only based on a single hospital admission, it is possible that some bilateral procedures may have occurred staged in a single hospital admission. We assume if that is case that the number is small and should not affect our results in a significant way, however it is still
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a limitation worth mentioning despite similar methodology being used in the orthopaedic literature [16]. Lastly, these data do not provide the authors with functional scores and follow-up, which can also be useful data when looking at large numbers over long period of time. Simultaneous bilateral total hip arthroplasty can be a useful treatment in the right patient. This is important to consider as the demand of patients in need of a hip arthroplasty continues to increase despite increasingly strained healthcare resources. However, there are concerns about increased complication risks, which impact patient outcomes and increase overall costs. Currently, surgeons in New York State are choosing simultaneous bilateral total hip arthroplasty less frequently, and further research is needed to determine when a simultaneous approach can be used without increasing overall risk to patients. References 1. Kurtz S, Ong K, Lau E, et al. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone Joint Surg Am 2007; 89(4):780. 2. Jaffe WL, Charnley J. Bilateral Charnley low-friction arthroplasty as a single operative procedure. A report of fifty cases. Bull Hosp Joint Dis 1971;32(2):198. 3. Nerubay J, Katznelson A. One-stage bilateral total hip replacement. Harefuah 1976; 90(3):113. 4. Ritter MA, Randolph JC. Bilateral total hip arthroplasty: a simultaneous procedure. Acta Orthop Scand 1976;47(2):203. 5. Berend ME, Ritter MA, Harty LD, et al. Simultaneous bilateral versus unilateral total hip arthroplasty an outcomes analysis. J Arthroplasty 2005;20(4):421. 6. Cammisa Jr FP, O'Brien SJ, Salvati EA, et al. One-stage bilateral total hip arthroplasty. A prospective study of perioperative morbidity. Orthop Clin North Am 1988;19(3):657. 7. Eggli S, Huckell CB, Ganz R. Bilateral total hip arthroplasty: one stage versus two stage procedure. Clin Orthop Relat Res 1996;328:108. 8. Lorenze M, Huo MH, Zatorski LE, et al. A comparison of the cost effectiveness of one-stage versus two-stage bilateral total hip replacement. Orthopedics 1996;21(12):1249. 9. Macaulay W, Salvati EA, Sculco TP, et al. Single-stage bilateral total hip arthroplasty. J Am Acad Orthop Surg 2002;10(3):217. 10. Reuben JD, Meyers SJ, Cox DD, et al. Cost comparison between bilateral simultaneous, staged, and unilateral total joint arthroplasty. J Arthroplasty 1998;13(2):172. 11. Della Valle CJ, Idjadi J, Hiebert RN, et al. The impact of medicare reimbursement policies on simultaneous bilateral total hip and knee arthroplasty. J Arthroplasty 2003;18(1):29. 12. Mendenhall Associates. Hip and knee implant prices rise 6.3%. Orthop Netw News 2006;17:6. 13. Lyman S, Koulouvaris P, Sherman S, et al. Epidemiology of anterior cruciate ligament reconstruction: trends, readmissions, and subsequent knee surgery. J Bone Joint Surg Am 2009;91(10):2321. 14. Onyekwelu I, Khatib O, Zuckerman JD, et al. The rising incidence of arthroscopic superior labrum anterior and posterior (SLAP) repairs. J Shoulder Elbow Surg 2012;21(6):728. 15. Quan JM. SPARCS: the New York State health care data system. J Clin Comput 1980; 8(6):255. 16. Meehan JP, Danielsen B, Tancredi DJ, et al. A population-based comparison of the incidence of adverse outcomes after simultaneous-bilateral and staged-bilateral total knee arthroplasty. J Bone Joint Surg Am 2011;93(23):2203. 17. Charlson ME, Pompei P, Ales KL, et al. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis 1987;40(5):373. 18. Deyo RA, Cherkin DC, Ciol MA. Adapting a clinical comorbidity index for use with ICD9-CM administrative databases. J Clin Epidemiol 1992;45(6):613. 19. Bozic KJ, Ward L, Vail TP, et al. Bundled payments in total joint arthroplasty: targeting opportunities for quality improvement and cost reduction. Clin Orthop Relat Res 2014;472(1):188.
Please cite this article as: Glait SA, et al, Comparing the Incidence and Clinical Data for Simultaneous Bilateral Versus Unilateral Total Hip Arthroplasty in New York State Be..., J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.05.046
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Comparing the Incidence and Clinical Data for Simultaneous Bilateral Versus Unilateral Total Hip Arthroplasty in New York State Between 1990 and 2010 Sergio A. Glait, MD , Omar N. Khatib, MD, Ankit Bansal, MD, Jason P. Hochfelder, MD, James D. Slover, MD Department of Orthopaedic Surgery, NYU Langone Medical Center Hospital for Joint Diseases, New York, New York
a r t i c l e
i n f o
Article history: Received 14 May 2014 Accepted 21 May 2015 Available online xxxx Keywords: bilateral hip arthroplasty incidence complications epidemiology
a b s t r a c t A New York State database reported information on all total hip arthroplasty cases between 1990 and 2010 comparing unilateral (242,588 cases) to simultaneous bilateral (4538 cases) procedures. Our data showed that the population incidence of this surgery increased 120.2% over twenty years, yet the proportionate number of simultaneous cases has decreased. Simultaneous procedures were found to occur more commonly in younger patients with private insurance. In addition, bilateral procedures showed an increase in PE, DVT, length of stay, and discharge to rehab facilities; whereas mortality and blood transfusions compared to unilateral procedures showed no difference. © 2015 Elsevier Inc. All rights reserved.
In the United States, total hip arthroplasty has become an increasingly sought after operation to improve a patient’s function from osteoarthritis of the hip. Projections have demonstrated that by the year 2030 the demand for primary total hip arthroplasty is estimated to grow to 572,000 cases per year [1]. Increases in life expectancy and a growing active elderly population from the baby-boom era will cause the demand for hip arthroplasty procedures to continue to rise over the coming years. For patients with bilateral disease, a decision about performing the procedures simultaneously or staged by some interval must be made by the surgeon and patient. Simultaneous bilateral THA has been performed since the 1970s and it has been a repeated topic examined in the orthopaedic literature [2–4]. Many surgeons fear that performing a bilateral procedure puts the patient at increased risk of complications, and some studies have supported this idea [5]. However, other studies have shown that simultaneous bilateral THA is effective in relieving pain and improving function without significantly increasing perioperative complications [6–10]. In addition, it may be cost-effective to perform simultaneous procedures where appropriate in a single hospital admission. It is estimated that 60% of hip arthroplasty procedures are paid by the government under the Centers for Medicare and Medicaid Services (CMS) [1]. In 1992, Medicare reimbursement for a second total joint
One or more of the authors of this paper have disclosed potential or pertinent conflicts of interest, which may include receipt of payment, either direct or indirect, institutional support, or association with an entity in the biomedical field which may be perceived to have potential conflict of interest with this work. For full disclosure statements refer to http://dx.doi.org/10.1016/j.arth.2015.05.046. Reprint requests: Sergio A. Glait, MD, 301 E 17th street, 14 flr, New York, NY 10003.
arthroplasty decreased 50% if performed within 90 days of the first procedure [11]. Physician reimbursement has decreased 39% between 1991 and 2006 [12]. In addition, the need to decrease healthcare spending, particularly on total joint arthroplasty procedures, has become an issue of paramount concern. The performance of simultaneous bilateral THA may be one way to do this through the elimination of an extra hospitalization by not staging the procedure. This study aims to compare the incidence and complications of simultaneous THA to unilateral THA over the past 20 years in New York State with the hypothesis that the incidence of simultaneous THA procedures has changed over time and that this procedure results in more complications compared to unilateral THA procedures.
Materials and Methods The Statewide Planning and Research Cooperative System (SPARCS) database from the New York State Department of Health was established in 1979 to record all inpatient hospital admissions under Public Health Law. Since then, SPARCS has streamlined this collection process in accordance with the Universal Data Set specifications. Previously published studies have used the SPARCS database to report epidemiologic data for various diseases and operative procedures [13–15]. The de-identified patient database was utilized to review all unilateral and simultaneous bilateral total hip arthroplasty procedures performed between 1990 and 2010 during a single hospital admission. The SPARCS inpatient registry was queried for ICD-9-CM v3 code 81.51 “Total Hip Arthroplasty (THA)”. Hospital admissions with only one code 81.51 were recorded as unilateral procedures, and admissions with two codes
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Please cite this article as: Glait SA, et al, Comparing the Incidence and Clinical Data for Simultaneous Bilateral Versus Unilateral Total Hip Arthroplasty in New York State Be..., J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.05.046
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of 81.51 were recorded as simultaneous bilateral THA. This methodology has been previously published in peer-reviewed journals [16]. To minimize the likelihood of attaining skewed demographical results, cases where patient age was not properly recorded were also excluded from analysis (346 cases, 0.001% of dataset). The obtained data were adjusted for differences in population size, as reported by the New York State Census database. Trends in incidence and demographics of unilateral and simultaneous bilateral THA were reviewed along with insurance status, primary diagnoses, hospital length of stay, disposition (home vs. rehabilitation), blood transfusions, and complications including mortality, deep vein thrombosis (DVT) and pulmonary embolism (PE). Charlson comorbidity scores were calculated for every patient using methods described by Charlson et al with scoring based on ICD-9 codes as outlined by Deyon et al whereby points were assigned for various co-morbidities such as myocardial infarction, congestive heart failure, peripheral vascular disease [17,18]. Secondary analyses of the effect of surgical volume were performed based on a high and low volume group. The high volume group was defined as all surgeons who performed the upper 50% of all procedures (i.e. for all simultaneous bilateral THA procedures the high volume group is composed of all surgeons who performed 50% of all procedures). The low volume group was defined as the remaining group of surgeons not in the high volume group (i.e. lower 50% of procedures). The data were stratified into two time periods to analyze trends with respect to time, with time period 1 defined as 1990–1999 and time period 2 defined as 2000–2010. SAS v9.3 (SAS institute, Cary, NC) was used for all data processing and statistical analyses. A paired Student t-test was used to compare findings between group 1 (unilateral THA) and group 2 (simultaneous bilateral THA) for continuous variables. A chi-squared test was used to compare categorical analyses with statistical significance set a priori at the .05 level. Results Between 1990 and 2010 there was a total number of 4538 simultaneous bilateral total hip arthroplasty procedures performed compared to 242,588 unilateral total hip arthroplasty procedures in New York State. In 1990–1999, there were 1768 simultaneous bilateral procedures compared to 86,144 unilateral THA procedures. In 2000–2010, there were 2770 simultaneous bilateral procedures compared to 156,444 unilateral THA procedures. A summary of patient demographic data from the SPARCs database is shown in Table 1. Demographic data comparing these two procedures demonstrate that more males had a simultaneous bilateral THA procedure compared to females (51.2% versus 48.8%; P b 0.05) between the years 1990 and 2010. However, women did have this procedure performed more frequently than men between the years of 1990 and 1999 (52.1% versus 47.9%). The average age of patients receiving a simultaneous bilateral THA procedure was significantly younger than those receiving unilateral procedures (56.7 years versus 65.9 years; P b 0.05). Lastly, a statistically higher percentage of patients with simultaneous bilateral THA had private insurance (66.6%) compared to a federally based insurance plan (33.4%). This trend was consistently seen between the two time periods studied with an increase in the number of patients with private versus federal insurance (72.1% versus 27.9%) having a simultaneous THA procedure in the latter half of the study period (2000–2010). Since 1990 the population-adjusted incidence (cases per 100,000) of total hip arthroplasty procedures has steadily increased 120.2% from 40.6 to 89.4 cases (Fig. 1). Fig. 2 shows the percent incidence of simultaneous bilateral THA, which decreased from 2.28% in 1990 to 1.51% in 2010. Table 2 demonstrates a summary of clinical data collected from the SPARCS database. Between 1990 and 1999 the average length of stay for a simultaneous bilateral THA was 12.75 ± 5.15 days compared to 9.33 ± 3.22 days for a unilateral THA (P b 0.05). This was reduced significantly between 2000 and 2010 to 5.92 ± 0.56 and 4.53 ± 0.42 days respectively for bilateral and unilateral THA procedures
Table 1 Patient Demographic Data Between 1990 and 2010. Bilateral THA
Unilateral THA
P Value
Demographics Female Patients (%) 1990–1999 2000–2010 Male Patients (%) 1990–1999 2000–2010 Patient Age (mean) 1990–1999 2000–2010
48.8 52.1 46.8 51.2 47.9 53.2 56.7 ± 13.4 59.5 56.3
57.9 59.3 57.1 42.1 40.7 42.9 65.9 ± 13.0 70.4 65.6
b0.00001 b0.00001 b0.00001 b0.00001 b0.00001 b0.00001 b0.00001 b0.00001 b0.00001
Primary Diagnosis Osteoarthritis (%) Femur Fracture (%) Aseptic Necrosis (%) RA, Infl Arthritis (%) Hip Dysplasia (%)
80 0.8 7.4 6.7 0.5
78.5 5.4 4.4 3.6 0.2
n/a n/a n/a n/a n/a
Insurance Federal Insurance (%) 1990–1999 2000–2010 Private Insurance (%) 1990–1999 2000–2010
33.4 42.6 27.9 66.6 57.4 72.1
53.1 63.2 48 46.9 36.8 52
b0.00001 b0.00001 b0.00001 b0.00001 b0.00001 b0.00001
Percentages based on 4538 bilateral (1768 cases in 1990–99 and 2770 cases in 2000–2010) and 242,588 unilateral (86,144 cases in 1990–99 and 156,444 cases in 2000–2010) procedures. Federal insurance includes Medicare, Medicaid, CHAMPUS, and other federal programs. Private insurance includes workers compensation, self-pay, and other non-federal insurance programs.
(P b 0.05). However, the cumulative length of stay between 2000 and 2010 shows a significantly reduced length of stay for simultaneous bilateral THA compared to unilateral procedures (5.92 vs. 9.06 days; P b 0.05). Disposition of patients was analyzed as being discharged either to home or to a rehabilitation service. When comparing all years studied, significantly more unilateral THA procedures were discharged home (51.69%) compared with simultaneous bilateral THA procedures (34.51%). This trend remained consistent when looking at the two different time periods. There was no statistically significant difference in non-cumulative mortality rates between simultaneous bilateral and unilateral THA procedures (0.2% and 0.4% respectively; P N 0.05). However, when examining the different time periods for mortality there was a significant increase in mortality with unilateral THA procedures (0.72%) compared to simultaneous bilateral THA (0.23%) between the years of 1990 and 1999. There is a statistically significant increase of non-cumulative rates of DVT (2.16% versus 0.84%; P b 0.05) and PE (0.79% versus 0.37%; P b 0.05) when comparing simultaneous bilateral THA procedures to unilateral THA. These increased trends are also consistent when looking at the two time periods as well. Cumulative rates of simultaneous bilateral THA and unilateral THA show similar but higher rates of DVT (2.16% and 1.68%; P = 0.0099) and PE (0.79% and 0.74%; P = 0.66) for the bilateral THA group in all years studied. Charlson co-morbidity scores were grouped as being a score of either zero or greater than one. Simultaneous bilateral THA patients were healthier at baseline (score = 0; 77.5%) versus unilateral THA patients (score = 0; 69.8%) based on the Charlson co-morbidity index. In addition, looking at blood transfusion data between groups showed that overall 92% of unilateral THA and 95% of simultaneous bilateral procedures did not receive a blood transfusion. In those patients that did receive a blood transfusion there was no significant difference between the bilateral and unilateral THA groups (4.1 units versus 3 units respectively; P = 0.24). Lastly, clinical data were grouped in terms of surgical volume as described in the materials and methods section (Table 3). For all years
Please cite this article as: Glait SA, et al, Comparing the Incidence and Clinical Data for Simultaneous Bilateral Versus Unilateral Total Hip Arthroplasty in New York State Be..., J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.05.046
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Populated-Adjusted Incidence of all THA 100.0 90.0 80.0
Cases per 100,000
70.0 60.0 50.0 40.0 30.0 20.0 10.0 0.0
Fig. 1. Population-adjusted incidence of all total hip arthroplasty procedures performed in New York State.
(1990–2010) there were 12 surgeons that performed 50% of all simultaneous bilateral THA procedures compared to 389 surgeons that were in the lower 50% group for the same procedure. The threshold case volume for the top 12 surgeons in the upper 50-percentile simultaneous bilateral group was a minimum of 90 cases between 1990 and 2010. This threshold value varied between time periods. Between 1990 and 1999 only 7 surgeons made up the top 50% group with a minimum of 56 cases (top surgeon with 205) while 12 surgeons made up the group between 2000 and 2010 with a minimum of 60 cases (top surgeon with 235). Similarly, there were 121 surgeons that performed 50% of all unilateral THA procedures compared to 5849 surgeons in the lower 50% group for the same procedure. The threshold case volume for the top 121 surgeons in the upper 50-percentile unilateral group was a
minimum of 490 cases between 1990 and 2010. Splitting this up between time periods showed that in 1990–1999 121 surgeons made up the top 50% group with a minimum of 167 cases (top surgeon with 2864) while 95 surgeons made up the upper group between 2000 and 2010 with a minimum of 400 cases (top surgeon with 3304). Data showing the number of surgeons in each time period are also shown in Table 3. The high volume surgeon group showed better clinical data when compared to the low volume group as shown in Table 3. Blood transfusions were significantly lower in the high volume group compared to the low volume group for simultaneous bilateral THA (2.16% vs. 7.36%; P b 0.0001). Similarly, blood transfusions were significantly lower in the high volume group compared to the low volume group for unilateral
Percent of Bilateral THA Cases 2.50%
% of all THA cases
2.00%
1.50%
1.00%
0.50%
0.00% 1990
1992
1994
1996
1998
2000
2002
2004
2006
2008
2010
Year Fig. 2. Percent incidence of simultaneous bilateral total hip arthroplasty procedures performed in New York State.
Please cite this article as: Glait SA, et al, Comparing the Incidence and Clinical Data for Simultaneous Bilateral Versus Unilateral Total Hip Arthroplasty in New York State Be..., J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.05.046
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Table 2 Clinical Data Collected Between 1990 and 2010.
Length of Stay a 1990–1999 (days) 2000–2010 (days)
Bilateral THA
Unilateral THA
P Value
12.75 5.92
9.33 4.53
b0.0001 b0.0001
Disposition Home 1990–1999 (%) Rehab 1990–1999 (%) Home 2000–2010 (%) Rehab 2000–2010 (%) Home All Years (%) Rehab All Years (%)
58.52 41.48 19.22 80.78 34.51 65.49
69.30 30.70 42.12 57.88 51.69 48.31
Complications a Mortality all years (%) 1990–1999 2000–2010 DVT all years (%) 1990–1999 2000–2010 PE all years (%) 1990–1999 2000–2010
0.2 0.23 0.22 2.16 3.45 1.34 0.79 0.85 0.76
0.4 0.72 0.23 0.84 1.21 0.64 0.37 0.44 0.32
0.059 0.015 0.89 b0.000001 b0.001 b0.001 b0.000001 0.01 b0.001
Charlson Co-Morbidity Score N 1 (%) Score = 0 (%)
22.5 77.5
30.2 69.8
b0.0001 b0.0001
b0.001 b0.001 b0.001
Percentages based on 4538 bilateral (1768 cases in 1990–99 and 2770 cases in 2000–2010) and 242,588 unilateral (86,144 cases in 1990–99 and 156,444 cases in 2000–2010) procedures. Charlson comorbidity scores represent data between all years studied. a Non-cumulative values.
THA (6.54% vs. 8.42%; P b 0.0001). These trends were also consistent between both time periods examined as shown in Table 3. When analyzing disposition based on surgical volume it was found that high volume surgeons discharge a significantly higher number of patients home compared to the low volume group when looking at both simultaneous bilateral THA (37.9% versus 31.1%; P b 0.0001) and unilateral THA groups (52.5% versus 50.9%; P b 0.0001). Differences between time periods can be seen in Table 3. Interestingly, there was no significant difference in simultaneous bilateral THA in terms of discharge home between the high volume and low volume surgeons between the years of 2000 and 2010. Mortality was also analyzed based on surgical volume. When looking at all years (1990–2010) it was found that high volume surgeons had significantly lower mortality rates than low volume surgeons in both the simultaneous bilateral THA (0.04% versus 0.4%; P b 0.0001) and unilateral THA groups (0.12% versus 0.68%; P b 0.0001). This significant trend was also seen in the different time periods except between 2000 and 2010 for the simultaneous bilateral THA group. Discussion Our study aimed to compare the incidence and complications of simultaneous THA to unilateral THA procedures over the past 20 years in New York State with the hypothesis that simultaneous bilateral procedures are decreasing in frequency and have higher complication rates. Orthopaedic surgeons in New York State are performing less simultaneous bilateral THA procedures despite the increasing incidence of total hip arthroplasty. Male patients with private insurance who are young and healthy are the majority having a simultaneous bilateral THA done. When looking at simultaneous bilateral THA patients, DVT and PE occur significantly more, whereas mortality and blood transfusions are not significantly increased. In addition, more patients in this group are discharged to rehab facilities. Lastly, surgeons who perform a majority of these procedures have better outcomes in their patients. There are several possible explanations for the trend of reduced simultaneous bilateral total hip arthroplasties in New York State. From a
Table 3 Percentages Based on 4538 Bilateral (1768 Cases in 1990–99 and 2770 Cases in 2000–2010) and 242,588 Unilateral (86,144 Cases in 1990–99 and 156,444 cases in 2000–2010) Procedures.
# of Surgeons/Cases Threshold a Upper 50% of procedures (all) 1990–1999 2000–2010 Lower 50% of procedures (all) 1990–1999 2000–2010 Clinical Data Blood Transfusions (%) High Volume (all years) 1990–1999 2000–2010 Low Volume (all years) 1990–1999 2000–2010 Disposition (% Going Home) High Volume (all years) 1990–1999 2000–2010 Low Volume (all years) 1990–1999 2000–2010 b Mortality (%) High Volume (all years) 1990–1999 2000–2010 Low Volume (all years) 1990–1999 2000–2010
Bilateral THA
Unilateral THA
12/90 7/56 12/60 389 242 228
121/490 121/167 95/400 5849 3177 3822
2.16 1.14 2.84 7.36 7.86 6.94
6.54 7.96 4.97 8.42 10.51 8.04
37.89 64.3 19.26 31.12 52.8 19.18
52.5 70.37 46.64 50.9 68.23 37.62
0.04 0 0.07 0.4 0.46 0.36
0.12 0.28 0.08 0.68 1.15 0.38
Blood transfusion data are based on whether a patient did or did not receive a blood transfusion and does not relate to the number of units given. All values are statistically significant when comparing high versus low volume in a given category except for those values that are bolded and italicized. a Data are categorized based on the number of high volume (surgeons performing upper 50% of the surgical volume for a given procedure) and low volume (surgeons performing the lower 50% of the surgical volume for a given procedure) surgeons. Case threshold represents the minimum number of cases performed to be included in the top 50% group. b Non-cumulative values.
patient safety perspective, our study showed that there is no significant increase in mortality when comparing non-cumulative rates of simultaneous bilateral versus unilateral THA procedures within the 20-year period. Interestingly, mortality did show an increase in the unilateral group compared to the simultaneous bilateral group between the years of 1990 and 1999 but the reason for this is not known. One plausible explanation for this finding can be that prophylaxis for thromboembolism was less standardized in the early 1990s coupled with the fact that the unilateral group as a whole was older with more comorbidities as evidenced by our Charlson co-morbidity index seen in Table 1. This may have led to a higher mortality in the unilateral THA group. On the other hand, surgeons who perform the majority of these procedures (top 50% in terms of procedures performed) have a significantly decreased mortality rate compared to surgeons on the lower half of the volume curve as evidenced by our data in Table 3. Although we do not know which of these surgeons are fellowship trained, one can assume that the more specialized surgeons at high volume centers who perform the majority of arthroplasty procedures in New York State have less complication rates. Our data are also consistent with previous literature that demonstrated a higher risk of deep vein thrombosis and pulmonary embolism with simultaneous bilateral arthroplasty procedures [5]. These higher rates of PE and DVT are also evident when cumulative rates are taken into account. This may be a major reason surgeons are choosing simultaneous procedures less frequently, and also explains the lower average age of these patients having bilateral procedures (56.7 versus 65.9 years old). Blood transfusions on the other hand were not found to be
Please cite this article as: Glait SA, et al, Comparing the Incidence and Clinical Data for Simultaneous Bilateral Versus Unilateral Total Hip Arthroplasty in New York State Be..., J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.05.046
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significantly different between groups when looking at the overall 20 year data, however low volume surgeons did show a significant increase in transfusions compared to high volume surgeons. There are costs associated with an increase in venous thromboembolism as well as blood transfusions and this is another reason that surgeons maybe turning away from simultaneous bilateral THA in order to avoid both the added risk to the patient as well as increased hospital costs in a time when hospitals are trying to be cost-effective. Surgeons may have shifted away from performing more simultaneous bilateral THA procedures due to financial influences as well. Reimbursements for a second total joint arthroplasty if performed within 90 days are decreased compared to staging the procedure so that the second surgery is 90 days after the first [11]. Studies have shown that a 30-day episode of care for a bilateral total joint arthroplasty is less expensive overall ($43,600) compared to doubling the same expense for a unilateral total joint without any complications ($25,568) [19]. Perhaps with the changing healthcare system and an increased emphasis on cost savings, surgeons may increase the number of simultaneous bilateral THA procedures in the right patients that minimize the risks. New reimbursement models such as the bundled payment system that proposes to set a fixed payment for an entire episode of care (i.e. 90 days of charges for a total joint arthroplasty) may also have an impact. With bundled payment however, there is more of an incentive to quickly discharge patients home rather than sending them to a rehab facility and our data show that simultaneous bilateral THA patients go to rehab at significantly high rates and have longer hospital lengths of stay compared to the unilateral counterparts (34.5% versus 51.7% of patients as shown in Table 2). At this time, surgeons are choosing simultaneous procedures less frequently despite potential cost savings to the healthcare system, and it is unclear if this trend will change unless more studies can show that it is truly cost-effective in the right patient. This study has both strengths and limitations. One of its strengths includes the statewide data collection regarding total hip arthroplasty procedures over a twenty year period. This provided the authors with a large sample population that helps make accurate calculations and draw conclusions. However, this methodology has its flaws as well since the SPARCS database does not easily provide follow-up on patients. Our data are derived based on a single hospital admission for a given ICD-9 procedural code and therefore we cannot assess the readmission rates or complications that occur post-discharge. Knowing both of these data would add a significant difference to the cost for an entire episode of care and may help answer the question as to whether a simultaneous THA procedure is economically sound, however the study’s aim was not to perform a cost–benefit analysis. In addition, because our data are only based on a single hospital admission, it is possible that some bilateral procedures may have occurred staged in a single hospital admission. We assume if that is case that the number is small and should not affect our results in a significant way, however it is still
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a limitation worth mentioning despite similar methodology being used in the orthopaedic literature [16]. Lastly, these data do not provide the authors with functional scores and follow-up, which can also be useful data when looking at large numbers over long period of time. Simultaneous bilateral total hip arthroplasty can be a useful treatment in the right patient. This is important to consider as the demand of patients in need of a hip arthroplasty continues to increase despite increasingly strained healthcare resources. However, there are concerns about increased complication risks, which impact patient outcomes and increase overall costs. Currently, surgeons in New York State are choosing simultaneous bilateral total hip arthroplasty less frequently, and further research is needed to determine when a simultaneous approach can be used without increasing overall risk to patients. References 1. Kurtz S, Ong K, Lau E, et al. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone Joint Surg Am 2007; 89(4):780. 2. Jaffe WL, Charnley J. Bilateral Charnley low-friction arthroplasty as a single operative procedure. A report of fifty cases. Bull Hosp Joint Dis 1971;32(2):198. 3. Nerubay J, Katznelson A. One-stage bilateral total hip replacement. Harefuah 1976; 90(3):113. 4. Ritter MA, Randolph JC. Bilateral total hip arthroplasty: a simultaneous procedure. Acta Orthop Scand 1976;47(2):203. 5. Berend ME, Ritter MA, Harty LD, et al. Simultaneous bilateral versus unilateral total hip arthroplasty an outcomes analysis. J Arthroplasty 2005;20(4):421. 6. Cammisa Jr FP, O'Brien SJ, Salvati EA, et al. One-stage bilateral total hip arthroplasty. A prospective study of perioperative morbidity. Orthop Clin North Am 1988;19(3):657. 7. Eggli S, Huckell CB, Ganz R. Bilateral total hip arthroplasty: one stage versus two stage procedure. Clin Orthop Relat Res 1996;328:108. 8. Lorenze M, Huo MH, Zatorski LE, et al. A comparison of the cost effectiveness of one-stage versus two-stage bilateral total hip replacement. Orthopedics 1996;21(12):1249. 9. Macaulay W, Salvati EA, Sculco TP, et al. Single-stage bilateral total hip arthroplasty. J Am Acad Orthop Surg 2002;10(3):217. 10. Reuben JD, Meyers SJ, Cox DD, et al. Cost comparison between bilateral simultaneous, staged, and unilateral total joint arthroplasty. J Arthroplasty 1998;13(2):172. 11. Della Valle CJ, Idjadi J, Hiebert RN, et al. The impact of medicare reimbursement policies on simultaneous bilateral total hip and knee arthroplasty. J Arthroplasty 2003;18(1):29. 12. Mendenhall Associates. Hip and knee implant prices rise 6.3%. Orthop Netw News 2006;17:6. 13. Lyman S, Koulouvaris P, Sherman S, et al. Epidemiology of anterior cruciate ligament reconstruction: trends, readmissions, and subsequent knee surgery. J Bone Joint Surg Am 2009;91(10):2321. 14. Onyekwelu I, Khatib O, Zuckerman JD, et al. The rising incidence of arthroscopic superior labrum anterior and posterior (SLAP) repairs. J Shoulder Elbow Surg 2012;21(6):728. 15. Quan JM. SPARCS: the New York State health care data system. J Clin Comput 1980; 8(6):255. 16. Meehan JP, Danielsen B, Tancredi DJ, et al. A population-based comparison of the incidence of adverse outcomes after simultaneous-bilateral and staged-bilateral total knee arthroplasty. J Bone Joint Surg Am 2011;93(23):2203. 17. Charlson ME, Pompei P, Ales KL, et al. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis 1987;40(5):373. 18. Deyo RA, Cherkin DC, Ciol MA. Adapting a clinical comorbidity index for use with ICD9-CM administrative databases. J Clin Epidemiol 1992;45(6):613. 19. Bozic KJ, Ward L, Vail TP, et al. Bundled payments in total joint arthroplasty: targeting opportunities for quality improvement and cost reduction. Clin Orthop Relat Res 2014;472(1):188.
Please cite this article as: Glait SA, et al, Comparing the Incidence and Clinical Data for Simultaneous Bilateral Versus Unilateral Total Hip Arthroplasty in New York State Be..., J Arthroplasty (2015), http://dx.doi.org/10.1016/j.arth.2015.05.046