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Ambulatory Spine Surgery: A Survey Study
Evan O. Baird1Sasha C. Brietzke2Alan D. Weinberg2Steven J. McAnany1Sheeraz A. Qureshi1
Samuel K. Cho1Andrew C. Hecht1
1Department of Orthopaedics, Mount Sinai School of Medicine,
New York, New York, United States
2Department of Health Evidence and Policy, Mount Sinai School of
Medicine, New York, New York, United States
Global Spine J 2014;4:157–160.
Address for correspondence Andrew C. Hecht, MD, 5 East 98th Street,
Box 1188, New York, NY 10029, United States
(e-mail: andrew.hecht@mountsinai.org).
Introduction
The performance of ambulatory surgical procedures is on the
rise across all surgical fields, ranging from thyroid surgery1to
cholecystectomy.2The field of orthopedic surgery has fol-
lowed a similar path, with an ever-increasing practice trend
of outpatient knee and shoulder arthroscopy3,4 and more
recently lumbar and cervical spine surgery.5–8Given these
trends, we sought to assess the outpatient spine surgery
environment and report the types of cases being performed
by those surgeons who perform spine surgery in this setting.
We conducted a survey of spine surgeon members of the
International Society for the Advancement of Spine Surgery
(ISASS) regarding their experience with ambulatory spine
surgery. In so doing, we hoped to characterize the current
practice of spine surgeon members of this society, including
Keywords
►spine surgery
►ambulatory surgery
►complications
Abstract Study Design Cross-sectional study.
Objective To assess the current practices of spine surgeons performing ambulatory
surgery in the United States.
Methods An electronic survey was distributed to members of the International
Society for the Advancement of Spine Surgery. Data were initially examined in a
univariate manner; variables with a pvalue <0.25 were entered into a multiple logistic
regression model. All statistical analyses were performed using the SAS System software
Version 9.2 (SAS Institute, Inc., Cary, North Carolina, United States).
Results Overall, 84.2% of respondents performed some manner of ambulatory spine
surgery, and 49.1% were investors in an ambulatory surgery center. Surgeon investors in
ambulatory surgery centers were more likely to perform procedures of increased
complexity than noninvestors, though limited data precluded a statistical correlation.
Surgeons in private practice were more likely to perform ambulatory surgery (94.3%;
p¼0.0176), and nonacademic surgeons were both more likely to invest in ambulatory
surgery centers (p¼0.0024) and perform surgery at least part of the time in a surgery
center (p¼0.0039).
Conclusions Though the numbers were too few to calculate statistical significance,
there was a trend toward the performance of high-risk procedures on an ambulatory
basis being undertaken by those with investment status in an ambulatory center. It is
possible that this plays a role in the decision to perform these procedures in this setting
versus that of a hospital, where a patient may have better access to care should a
complication arise requiring emergent assessment and treatment by a physician. This
decision should divest itself of financial incentives and focus entirely on patient safety.
received
March 24, 2014
accepted
April 29, 2014
published online
June 9, 2014
© 2014 Georg Thieme Verlag KG
Stuttgart · New York
DOI http://dx.doi.org/
10.1055/s-0034-1378142.
ISSN 2192-5682.
Global Spine Journal Original Article 157
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the characteristics of respondents performing ambulatory
surgery, the surgical procedures being performed, the setting
of ambulatory surgery as well as the associated self-reported
complications encountered during the performance of am-
bulatory surgery.
Materials and Methods
The electronic survey consisted of 25 questions and was
distributed to members of the ISASS over a 3-month period
from July through September 2012. After this time, the
response Web link was disabled. By providing each respon-
dent with a unique link, we avoided multiple responses from
a single participant.
For the analysis of factors potentially associated with
ambulatory spine surgery, data were first examined in a
univariate manner using the Student ttest for continuous
variables and Fisher exact test for discrete data. For the
multivariate analysis, variables with a pvalue <0.25 were
entered into a multiple logistic regression model, because we
interpreted these variables as independent factors associated
with the event or outcome of interest, over and above (adjusted
for) other potential factors included in the equation. The
logistic equation generates pvalues and odds ratios for each
explanatory variable’s association with the outcome of inter-
est. For all statistical analysis, data were analyzed using the SAS
System software Version 9.2 (SAS Institute, Inc., Cary, North
Carolina, United States). The pvalues were not adjusted for
multiple testing and a potential inflation of the type I error.
Results
The number of responses from U.S.-based surgeons totaled
57. We found that 75.4% of respondents were trained in
orthopedic surgery, with the remainder having been trained
in neurosurgery. In addition, 87.7% of surgeon respondents
were spine fellowship trained; 61.4% were in private practice,
31.6% in academic practice, and 7.0% in a hospital employ-
ment position. The majority (54.4%) classify themselves as
practicing in an urban environment, with 42.1% in a suburban
environment and 3.5% in a rural area. 84.2% of respondents
performed some manner of ambulatory spine surgery,
whether in a hospital or ambulatory surgery center setting.
Of the responding surgeons, 49.1% invest in an ambulatory
surgery center; of those who perform surgery in such a
center, 81.5% are investors; and in those performing ambula-
tory surgery in a hospital setting only, 21.1% invest in a
surgery center (►Table 1). Common procedures were single-
(performed by 70.8% of surgeons) or multiple-level (41.7%)
lumbar microdiskectomy, single- (62.5%) or multiple-level
(33.3%) lumbar laminectomy, and one- (54.2%) and two-level
(39.6%) anterior cervical diskectomy and fusion. Surgeon
investors in ambulatory surgery centers were more likely to
perform procedures of increased complexity (i.e., multilevel
anterior cervical fusion procedures) than noninvestors (21.4%
versus 3.4%); in other words, of those performing such
procedures, 85.7% were investors. The numbers in this analy-
sis were too small to perform statistical analysis.
Surgeons in private practice were more likely to perform
ambulatory surgery (94.3%; p¼0.0176), and nonacademic
surgeons (i.e., those in private practice or community hospi-
tal-based) were more likely to invest in ambulatory surgery
centers (67.6%; p¼0.0024) and perform surger y at least part
of the time in a surgery center (p¼0.0039; ►Table 2). In the
univariate analysis, status as an orthopedic surgeon (versus a
neurosurgeon) did not correlate with performance of outpa-
tient surgery (p¼0.5084), with investment in an ambulatory
surgery center (p¼0.3084), or with the location of the
ambulatory surgery (p¼0.9798; ►Table 3). Of note, taken
together as a group, being in practice for 20 years or less did
correlate with the likelihood of investing in a surgery center
(p¼0.0333; ►Table 2). Location of performance of ambula-
tory surgery did not appear to affect whether the primary
surgeon co-operated with another surgeon. Among those
performing ambulatory surgery at least sometimes in ambu-
latory surgery centers, 48.3% reported the availability of
23-hour observation should the patient require it; the
remainder indicated that transfer to another facility would
be necessary for further care. In addition, 10.3% of surgeons
reported a complication that could not be addressed in the
ambulatory center environment; 92% noted that in the event
of such a complication, there was a protocol in place designed
to manage such episodes.
Discussion
Cervical and lumbar spine surgery is being performed
more commonly on an ambulatory basis,5–8possibly
Table 1 Characteristics of survey respondents (n¼57)
Characteristic n
Fellowship training 50 (87.7%)
Orthopedic surgeon 43 (75.4%)
Neurosurgeon 14 (24.6%)
Private practice 35 (61.4%)
Academic practice 18 (31.6%)
Hospital employment 4 (7.0%)
Urban environment 31 (54.4%)
Suburban environment 24 (42.1%)
Rural environment 2 (3.5%)
0–5 y in practice 8 (14.0%)
6–10 y in practice 6 (10.5%)
11–20 y in practice 20 (35.1%)
>20 y in practice 23 (40.4%)
Perform ambulatory surgery 48 (84.2%)
Hospital setting 19 (39.6%)
Ambulatory surgery center 10 (20.8%)
Both 19 (39.6%)
Investment in ambulatory surgery center 28 (49.1%)
Global Spine Journal Vol. 4 No. 3/2014
Ambulatory Spine Surgery Baird et al.158
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driven by the development of minimally invasive techni-
ques, which has been shown to minimize immediate post-
operative pain and accelerate postoperative recovery.9–11
Anotherfactormaybesurgeonfinancial incentive
when performing the surgery in a physician-owned ambu-
latory surgery center.12 This survey was able to provide an
overview of the characteristics of surgeons performing
surgery on an outpatient basis, the location for the perfor-
mance of the surgeries, and the types of cases being
performed.
Based on the data gathered, practicing as a member of a
nonacademic practice correlated with the performance of
ambulatory surgery, the utilization of an ambulatory surgery
center, and investment in an ambulatory surgery center.
Likewise, being in practice for 20 or fewer years and being
a member of a nonacademic practice correlated with invest-
ment in an ambulatory surgery center.
Finally, as noted above, though the numbers were too
few to calculate statistical significance, there was a trend
toward performance of both surgery in ambulatory surgery
centers and procedures associated with increased risk
(i.e., multilevel anterior cervical fusion procedures) on an
ambulatory basis being undertaken largely by investors in
an ambulatory center. Given the financial incentives in-
volved in an ambulatory surgery center, it is possible that
this plays a role in the decision to perform these procedures
in this setting versus that of a hospital, where a patient may
have better access to care should a postoperative compli-
cation arise requiring emergent assessment and treatment
by a physician. Of some concern is that 8% of surgeons
performing spinal procedures did not have a mechanism for
dealing with complications that could not be managed in
the ambulatory surgery center. Last, 10.3% of surgeons
identified complications that could not be handled in their
center.
Limitations to our study include those inherent to survey
studies (sampling error, nonresponse error, coverage error)
and a relatively small number of respondents. Ideally, a study
such as ours would include survey distribution to a wider
range of spine surgeon professional societies, providing a more
thorough and accurate analysis of the patterns of performance
of spine surgery in the ambulatory setting. The authors
undertook this study not with the intention of criticizing the
use of ambulatory surgery centers for spine surgery as a whole,
but with the hope that this study will serve to open discussion
on the types of procedures that can be safely performed in an
ambulatory surgery center. This discussion should divest itself
of financial incentives and focus entirely on patient safety and
mechanisms to deal with complications that cannot be man-
aged in ambulatory centers.
Disclosures
The authors did not receive grants or outside funding in
support of their research or for preparation of this manu-
script. This manuscript does not require approval from our
Table 2 Multivariate logistic regression analyses
pOR (95% CI)
Model
Private practice setting versus performance of ambulatory
surgery
0.0176
a
7.700 (1.427–41.556)
Nonacademic practice setting versus performance of ambulatory
surgery at least part time in surgery center
0.0039
a
11.459 (2.187–60.048)
Nonacademic practice setting versus investment in surgery
center
0.0024
a
9.854 (2.245–43.241)
20 y in practice versus investment in surgery center 0.0333
a
4.050 (1.117–14.675)
Abbreviations: CI, confidence interval; OR, odds ratio.
a
p<0.05 (statistically significant).
Table 3 Univariate logistic regression analyses: surgeon characteristics versus likelihood of performing ambulatory surger y, location
of ambulatory surgery, and investment in an ambulatory surgery center
Variable Outcome Perform ambulatory
surgery
Ambulatory surgery at least
part time in surgery center
Invest in surgery center
Orthopedic specialist 0.5084 0.9798 0.3084
Nonacademic practice setting 0.0219
a
0.0039
a
0.0012
a
Urban practice location 0.4247 0.0466
a,b
0.2205
20 y in practice 0.3174 0.0467
a
0.0120
a
a
p<0.05 (statistically significant).
b
Based on measurement of suburban rather than urban location.
Global Spine Journal Vol. 4 No. 3/2014
Ambulatory Spine Surgery Baird et al. 159
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institution’s Institutional Review Board. This manuscript
does not describe the use of medical device(s)/drug(s).
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