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\begin{document}

\title{Preoperative Anesthesiology Consult Utilization in Ontario -- A
Population-Based Study}



\author[1]{Joanna Dion}%
\author[1]{Robert Campbell}%
\author[1]{Paul Nguyen}%
\author[1]{Jason Beyea}%
\affil[1]{Queen's University}%


\vspace{-1em}



  
  \date{May 17, 2024}


\begingroup
\let\center\flushleft
\let\endcenter\endflushleft
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\selectlanguage{english}
\begin{abstract}
ABSTRACT \selectlanguage{ngerman}¬ Rationale, aims and objectives: Physician consultations are a
limited resource. Anesthesiologists provide anesthesia during surgery
and procedures, prepare patients for surgery in preoperative clinics,
and provide postoperative care. This study sought to evaluate current
consultation usage patterns, with an aim to determine possible
opportunities for efficiency. Method: A retrospective comprehensive
population-based cohort study was performed, evaluating all hospitals in
the Canadian province of Ontario from 2002-2018. The main outcome
measures were American Society of Anesthesiologists (ASA) classification
of the patients, and whether the patients underwent surgery within 3
months following the anesthesia consultation. Results: A cohort of
2,023,499 patients, and a total of 2,920,100 preoperative anesthesia
consultations was obtained. The number of consults per year doubled
between 2003 (112,983/year) and 2017 (246,427/year). Each year, an
average of 19.32\% of the consults (range: 17.69-20.49\%) were for
patients that did not progress to having surgery. Of those that did have
surgery following the anesthesia consult, 37.23\% were ASA
Classification I or II. The most common surgical procedures (percent of
total) following anesthesia consult were: Knee implantation of internal
device (9.46\%), hip implantation of internal device (5.84\%), cataract
excision (4.09\%), repair of muscle of chest/abdomen (3.31\%), uterus
excision (2.76\%), and gallbladder excision (2.67\%). Conclusions: This
study reveals data on utilization and trends over time of preoperative
anesthesia consultations. Potential opportunities for optimization were
found, including patients who did not proceed to surgery, and healthier
patients undergoing low to moderate risk surgery that may not require
consultation.%
\end{abstract}\selectlanguage{ngerman}%



\sloppy


\textbf{Main Text}

\textbf{Introduction}

Recently, increasing attention has been focused on efficient utilization
of healthcare services. Approximately 1.2 million outpatient and 350,000
inpatient surgeries were performed in Ontario in
2014/2015\textsuperscript{1,2}. Many patients undergo preoperative
screening in the form of laboratory or imaging investigations or
consultation with an anesthesiologist. This process of investigations
and consultation optimizes patients medically by identifying and
improving unstable conditions which might result in less perioperative
complications\textsuperscript{3}.

As perioperative physicians, anesthesiologists provide significant
guidance to help determine which patients should undergo testing before
elective surgery. Since 2014, the Choosing Wisely Canada campaign has
endeavoured to help determine appropriate and necessary treatment by
medical specialty\textsuperscript{4}. The Choosing Wisely Canada
recommendations for anesthesia include the avoidance of laboratory or
other cardiovascular testing for asymptomatic patients undergoing lower
risk surgeries. Several studies assessing the use of investigations
prior to low risk surgery showed that many patients continue to undergo
potentially unnecessary testing\textsuperscript{5,6}.

There are currently no guidelines recommending appropriate use of
anesthesia consultation, and there appears to be significant practice
variation\textsuperscript{3,7}. Wijeysundera et.
al.\textsuperscript{8}studied the use of anesthesia consultation in and
found an increase in preoperative anesthesia consultations from 19\% in
1994 to 53\% in 2003. Patients who received anesthesia consultations had
lower risks of anxiety and day of surgery cancellations, as well as
slightly shorter hospital stays. Mortality risks were not different, and
questions regarding the cost-effectiveness of preoperative consultations
were raised. Overall, there appears to be a trend towards increasing use
of anesthesia consultation, even amongst patients undergoing low risk
surgeries, which potentially could result in inefficient use of health
care resources\textsuperscript{9}. Presumably, higher risk patients
undergoing more invasive surgeries will get the most benefit from
preoperative consultation\textsuperscript{3,7}. Similarly, there are no
specific guidelines for which patients can benefit from an internal
medicine consultation prior to surgery\textsuperscript{10}.

In the current climate of limited health care resources, the authors
sought to obtain information regarding current and historical usage of
preoperative anesthesia consults. Herein, we carried out a
population-based study to evaluate the use of preoperative anesthesia
consultation services.

\textbf{Methods}

\textbf{Overview, study population and study design}

We carried out a population-based study to evaluate usage of
preoperative anesthesia consultation in . is the largest province in ,
with a population of over 14 million residents. The Canadian healthcare
system is a publically funded and administered system, governed by the
Canada Health Act. This Act mandates comprehensive universal coverage
for all medically necessary services, including medical (anesthesiology)
consultations. Private health insurance for these services is
prohibited. As such, these consults are available to all persons
equally, and the data sources were population-based. Patients were
excluded if a valid patient identifier was not available, if age/sex
information was missing, or if residency was outside of . This study was
approved by the Queen's University Health Sciences \& Affiliated
Teaching Hospitals Research Ethics Board, project \#6025862.

\textbf{Data Sources and Data Linkage}

Administrative datasets housed at the ICES were used to obtain the data
for this study. ICES is an independent, non-profit research organization
funded by the Ontario Ministry of Health and Long Term Care whose data
holdings include all health care related events for the population of
Ontario. The Registered Persons Database (RPDB) is a repository of
demographic information for all residents of who are eligible for the
Ontario Health Insurance Plan (OHIP). RPDB is maintained by the
Ministry, and contains information on health card number, date of birth,
sex, address, and deceased date (where applicable). Personal identifying
information in RPDB is removed at ICES, and each unique health number is
converted into an anonymous unique identifier, the ICES Key Number
(IKN). The IKN is a common identifier that is used to link data sources
within ICES. The OHIP database contains data on the diagnosis and
fee-for-service claims submitted by physicians and paid by the universal
health care system. The Canadian Institute for Health Information
Discharge Abstract Database and Same Day Surgery database contain
information on all inpatient and day surgery visits, respectively,
abstracted from hospital records for patient diagnoses and procedures.

The datasets were created at ICES Queen's based on patients of all ages,
using physician OHIP billing for an outpatient anesthesia consult (OHIP
fee code: A015, A016) (Table 1) from April 1, 2002 to June 30, 2018, and
hospital discharge records from April 1, 2002 to September 30, 2018
(study period). Patients were excluded if they had missing age/sex data,
or were a resident of another province at the time of consultation or
surgery. These datasets were then linked to demographic data, and to
hospital inpatient and outpatient discharge data for surgeries.

The study cohort included all patients who underwent an outpatient
preoperative anesthesia consultation (A015, A016) during the study
period. The index date was the first use of these OHIP billing claims.
This cohort permitted reporting of counts and percentages of surgery,
and for those patients who underwent surgery, the ASA classification
(American Society of Anesthesiologists physical status classification
system) of the patients by the anesthesiologist at the time of surgery.
The ASA classification is used ubiquitously to stratify the general
health of patients whereby an ASA I patient is healthy with no medical
diagnoses, all the way up to an ASA V patient who is so medically
complex that he or she is not expected to survive for 24 hours with or
without surgical intervention (Table 2)\textsuperscript{11}. For ASA
III, IV, and V patients, there are respective anesthesia modifier
billing codes through OHIP. This is due to the increased complexity of
providing perioperative anesthesia care for patients with increased
comorbidities. There are no modifier ASA billing codes for patients who
are deemed ASA I or ASA II (healthier) at the time of surgery by the
attending anesthesiologist. As such, if a modifier for ASA III, IV, or V
was not used, the patient was presumed to be ASA I or II.

\textbf{Outcomes and Analyses}

This study sought to determine the volume of consults, and to determine
if the patient progressed to surgery. Also, for those patients who had
surgery, the ASA classification was determined. Cohorts including usage
of preoperative anesthesia consults over time, those who went on to have
surgery (specifically, the most significant surgical intervention during
the inpatient or day surgery visit), and ASA classification as assigned
at the time of surgery were created. Frequencies and percentages of
preoperative anesthesia consults, most common types of surgery and ASA
classifications were quantified. Modified Poisson regression analyses
were used to provide the relative risks of consults for the most common
types of surgery and place of preoperative anesthesia consults. To
account for the patient-level clusters of repeated surgeries over time,
the Poisson regression models used the generalized estimating equations
(GEE) approach.

Descriptive statistics and regression analyses were generated using the
SAS Enterprise Guide software version 7.1 (SAS Institute, Cary, NC) at
ICES.

\textbf{Results}

\textbf{Cohort characteristics}

Over the study period, 2,920,100 preoperative anesthesiology consults
were performed in Ontario on 2,023,499 patients. The average patient age
was 59.02 \selectlanguage{ngerman}± 19.28 years (range 1-108 years), and 46.43\% were male. The
annual volume of these consults doubled over the study period (Figure
1). Of patients who proceeded to have surgery within the 3 months after
the anesthesiology consult, 97.58\% of the consults were performed
electively in the outpatient anesthesiology clinic setting.

\textbf{Surgery}

Of the anesthesiology consults performed in Ontario, an average of
19.32\% (range: 17.69--20.49\%) of these consults were for patients who
did not proceed to surgery in the ensuing three months. Expanding the
post-consult window, averages of 18.58\% (ensuing 4 months), 17.67\%
(ensuing 6 months), and 16.15\% (ensuing 12 months) did not proceed to
surgery. Looking specifically at the ensuing three month window, the
results were stable over time (Figure 2). Of patients who proceeded to
surgery, joint replacement and cataract surgeries were the most common
procedures (Table 3).

\textbf{American Society of Anesthesiologists (ASA) Classification of
Surgical Patients}

The ASA classification of the patients was assigned at the time of
surgery by the attending anesthesiologist, through the respective
billing codes. Analysis of these codes revealed that over 37\% of
patients were classified as either ASA I or ASA II (Figure 3). However,
the percentage of patients receiving preoperative anesthesiology
consults who were ASA I or ASA II declined over the study period (Figure
4). ASA class I or II consults were slightly more likely to be ordered
by surgeons under age 36 and over age 60 (Figure 5). Patients undergoing
cataract surgery had a higher likelihood of receiving an anesthesia
consultation if they had an ASA I or II, whereas knee implant,
chest/abdominal muscle repair, bladder excision, and coronary artery
bypass were more likely to have a consult if they were ASA III-V (Table
3). Furthermore, there was notable variability in consults by
geographical region. In Ontario, healthcare geographical regions have
traditionally been divided into fourteen Local Health Integration
Networks (LHIN). In 2003, the proportion of consultations that were ASA
I/II ranged by LHIN from 38.6\% to 68.8\% of all preoperative anesthesia
consults. In 2017, this proportion ranged by LHIN from 20.2\% to 33.2\%
of all preoperative anesthesia consults.

\textbf{Discussion}

As health care costs continue to rise in Canada\textsuperscript{12},
more emphasis has been directed towards efficient usage of resources.
The first step is to evaluate the current landscape. As physicians,
there is an opportunity to address the health care system based on
medical necessity, and to look for efficiencies. This study evaluated a
large, comprehensive cohort from a single-payer healthcare system, and
identified current and historical anesthesia consult utilization.

Individual centres have demonstrated that preoperative anesthesia
consultations reduce patient anxiety\textsuperscript{13}, reduce
cancellations on the day of surgery\textsuperscript{14-16}, and reduce
hospital costs\textsuperscript{17}. It is unclear though whether these
same benefits are borne out when applied to a population.

The Canadian Institute for Health Information reports that 15.1\% of
health care expenditures are paid for physician
services\textsuperscript{18}. In addition to the physician costs, there
are costs for facility/infrastructure, additional personal (including
nurses, receptionists, custodial staff), laboratory testing, and medical
imaging. Furthermore, it has been reported that preoperative anesthesia
consultations result in higher rates of ordering possibly unnecessary
specialized testing, including echocardiography\textsuperscript{8}. It
is important to note that echocardiography provides minimal additional
prognostic information above clinical risk
factors\textsuperscript{19}and additional bloodwork, for example Brain
Natriuretic Peptide (BNP)\textsuperscript{20}.

A major concern from a surgical and health systems/resource management
standpoint is the possibility of cancellation on the day of surgery. As
well, the authors recognize that system and cultural differences exist
at different hospitals, and by different physicians, in terms of
utilization of these preoperative consultations. This is supported by
the present study, which described geographic variability in the usage
of preoperative anesthesiology consultations. However, the worry of
surgery cancellation may feed, at least in part, increased usage of
preoperative anesthesia consultations. It may be possible that through
the use of structured medical directives and identification of patients
in need of consultation by the hospital's presurgical screening clinic,
some fears can be mitigated. The authors acknowledge that this is a
much-needed area of research.

An interesting subgroup identified consisted of patients undergoing
preoperative anesthesia consults prior to cataract surgery. Thilen et
al.\textsuperscript{9} found a substantial increase from 1995 to 2006 in
preoperative consultation prior to cataract surgery. The current study
found that after knee and hip replacement, the third most common
operation leading to utilization of preoperative anesthesia consultation
was cataract surgery. This may be due in part to older and more
medically complex patients being offered cataract surgery than in the
past. Also, it may be that additional procedures are being completed at
the same time to address glaucoma or other concomitant issues. However,
it is also possible that policies and routine approaches in some centres
might find efficiencies by re-evaluating the need for such
consultations.

It is interesting that the percentage of ASA I and II patients who
receive preoperative anesthesia consultations has decreased markedly
over time (Figure 4). This may already reflect the strains and
limitations being placed on the healthcare system. There is a slight
tendency for early and late career surgeons to order more ASA I/II
preoperative consults compared to mid-career physicians (Figure 5). At
this time, it is not clear why this pattern was observed, however, the
findings are consistent with previous research showing a tendency for
younger physicians to order more preoperative
investigations\textsuperscript{21}. As our system responds to the
pressures of increasing numbers and comorbidities of patients, likely
many hospitals are already finding efficiencies. Also, the movement
towards limiting unnecessary preoperative testing (Choosing Wisely
Canada) is likely taking hold. The results of this study provide data to
further the discussion surrounding preoperative anesthesia
consultations.

There are limitations that are intrinsic to administrative data. There
are many good reasons why some ASA I and II patients should undergo
preoperative anesthesia consultation that may not appear in the datasets
used. For example, patient factors such as features predicting very
difficult airway management, language barrier, extreme anxiety
surrounding anesthesia or a personal or family history of problematic
anesthesia would be good indications for anesthesia consultation. These
factors might not be captured by the ASA classification in terms of ASA
III or above. Similarly, longer or more complex surgeries requiring
management including prone positioning, one-lung ventilation, or the
anticipation of significant blood loss or fluid shifts or potential for
significant postoperative pain would be reasons for anesthesia
consultation in a healthy patient. Having said this, these sorts of
surgeries were not in the top five most common procedures captured by
this study.

Data quality also relies on initial accurate coding by the physician and
hospital coders. A comparison of administrative data with hospital chart
data concluded that major events (surgical procedures, mortality,
patient demographics, primary diagnoses) are accurately
coded\textsuperscript{22}.

An interesting group of patients are those 19.3\% who underwent an
anesthesia consultation and then did not proceed to surgery within 3
months. There are a few possible explanations for this. First, it may be
that after discussion with the anesthesiologist the patient decided not
to go ahead with the surgical procedure. This can occur after an
individualized explanation of medical risks or postoperative predicted
morbidity or mortality based on patient and surgical factors. For
example, a medically complex patient may choose not to undergo a hip
replacement to avoid a potential postoperative complication. This is a
great use of the system and allowed patient autonomy and informed shared
decision making. Secondly, it may be that the surgery was postponed
outside the 3 month window due to medical or scheduling reasons. This
patient would then likely undergo surgery at a later time (after
potentially undergoing further pre-operative assessment). This is a
reality of our medical system, and offers opportunities to ensure we
repeat as little as medically necessary to get the patient ready for the
delayed surgery. Finally, after undergoing anesthesia consultation, the
patient may not undergo surgery because it is no longer required, or the
patient changes his or her mind -- unrelated to the anesthesiologist
assessment. Further understanding this group of patients could
potentially provide some areas for increasing efficiency.

The results demonstrated a doubling of anesthesia consults per year over
the course of the study. For a meaningful understanding of this number,
the denominator (number of surgeries per year) is needed. The authors
acknowledge that this information is not straightforward to obtain in a
reliable manner. To the best of our knowledge, the data from Statistics
Canada would be the most applicable. Evaluation of Statistics Canada
waiting times for non-emergency surgery\textsuperscript{23} revealed
that in Ontario, yearly surgical volumes increased modestly from 544,002
in 2005 to 704,890 in 2013, an increase of 29.6\%. The data from the
present study indicates a much larger increase for anesthesia consults
of 92.9\% (from 112,983 to 217,959) over this timeframe (2005-2013).
This may be due to many factors, including increased numbers of patient
medical comorbidities, increased surgical procedure complexity,
surgeon/anesthesiologist/hospital preference, and patient desire for
discussion surrounding the anesthetic itself.

\textbf{Conclusion}

This study reveals important data relating to the utilization and trends
over time of preoperative anesthesia consultations within a large
comprehensive population. Opportunities for discussion were found,
including consultations provided for patients who did not proceed to
surgery, and those healthier patients undergoing minimally to moderately
invasive surgeries. These findings are consistent with the Choosing
Wisely Canada section for anesthesia which suggests minimizing
preoperative testing for asymptomatic patients (synonymous with ASA
class I and II patients) undergoing minimally invasive surgeries. Future
studies are needed to evaluate the safety of allocating preoperative
anesthesiology consultations in particular groups, and the potential
healthcare system efficiencies and economic benefits of these
reductions.

\textbf{References}

1. Canadian Institute for Health Information, DAD/HMDB Inpatient
Hospitalizations: Volumes, Length of Stay, and Standardized Rates,
QuickStats.

2. Ontario Hospital Association, Quick Facts 2016: Ontario's Public
Hospitals. Available from:
https://www.oha.com/guidance-and-resources/hospital-physician-relations

3. Wijeysundera DN. Preoperative consultations by anesthesiologists.
Curr Opin Anaesthesiol. 2011 Jun;24:326-30.

4. Levinson W, Huynh T. Engaging physicians and patients in
conversations about unnecessary tests and procedures: Choosing Wisely
Canada. CMAJ. 2014;186:325-6.

5. Kirkham KR, Wijeysundera DN, Pendrith C, Ng R, Tu JV, Laupacis A,
Schull MJ, Levinson W, Bhatia RS. Preoperative testing before low-risk
surgical procedures. CMAJ. 2015;187:E349-E358.

6. Kirkham KR, Wijeysundera DN, Pendrith C, Ng R, Tu JV, Boozary AS,
Tepper J, Schull MJ, Levinson W, Bhatia RS. Preoperative Laboratory
Investigations: Rates and Variability Prior to Low-risk Surgical
Procedures. Anesthesiology. 2016;124:804-14.

7. Thilen SR, Wijeysundera DN, Treggiari MM. Preoperative Consultations.
Anesthesiol Clin. 2016;34:17-33.

8. Wijeysundera DN, Austin PC, Beattie WS, Hux JE, Laupacis A. A
population-based study of anesthesia consultation before major
noncardiac surgery. Arch Intern Med. 2009;169:595-602.

9. Thilen SR, Treggiari MM, Lange JM, Lowy E, Weaver EM, Wijeysundera
DN.

Preoperative consultations for medicare patients undergoing cataract
surgery. JAMA Intern Med. 2014;174:380-8.

10. Wijeysundera DN, Austin PC, Beattie WS, Hux JE, Laupacis A.
Variation in the practice of preoperative medical consultation for major
elective noncardiac surgery: a population-based study. Anesthesiology.
2012;116:25-34.

11. Abouleish AE, Leib ML, Cohen NH. ASA provides examples to each ASA
physical status class. ASA Monitor 2015; 79:38-9
http://monitor.pubs.asahq.org/article.aspx?articleid=2434536

12.
https://www.cihi.ca/en/health-spending/2018/national-health-expenditure-trends/how-has-health-spending-growth-changed-over-the-last-40-years

13. Klopfenstein CE, Forster A, Van Gessel E. Anesthetic assessment in
an outpatient consultation clinic reduces preoperative anxiety. Can J
Anaesth. 2000;47:511-5.

14. van Klei WA, Moons KG, Rutten CL, Schuurhuis A, Knape JT, Kalkman
CJ, Grobbee DE. The effect of outpatient preoperative evaluation of
hospital inpatients on cancellation of surgery and length of hospital
stay. Anesth Analg. 2002;94:644-9.

15. Ferschl MB, Tung A, Sweitzer B, Huo D, Glick DB. Preoperative clinic
visits reduce operating room cancellations and delays. Anesthesiology.
2005;103:855-9.

16. Farasatkish R, Aghdaii N, Azarfarin R, Yazdanian F. Can preoperative
anesthesia consultation clinic help to reduce operating room
cancellation rate of cardiac surgery on the day of surgery? Middle East
J Anaesthesiol. 2009;20:93-6.

17. Pollard JB, Garnerin P, Dalman RL. Use of outpatient preoperative
evaluation to decrease length of stay for vascular surgery. Anesth
Analg. 1997;85:1307-11.

18.
https://www.cihi.ca/en/health-spending/2018/national-health-expenditure-trends/where-is-most-of-the-money-being-spent-in-health-care-in-2018

19. Halm EA, Browner WS, Tubau JF, Tateo IM, Mangano DT.
Echocardiography for assessing cardiac risk in patients having
noncardiac surgery. Study of Perioperative Ischemia Research Group. Ann
Intern Med. 1996;125:433-41.

20. Duceppe E, Parlow J, MacDonald P, Lyons K, McMullen M, et. al.
Canadian Cardiovascular Society Guidelines on Perioperative Cardiac Risk
Assessment and Management for Patients Who Undergo Noncardiac Surgery.
Canadian Journal of Cardiology. 2017;33(1):17-32.

{\label{duceppe-e-parlow-j-macdonald-p-lyons-k-mcmullen-m-et.-al.-canadian-cardiovascular-society-guidelines-on-perioperative-cardiac-risk-assessment-and-management-for-patients-who-undergo-noncardiac-surgery.-canadian-journal-of-cardiology.-201733117-32.}}

21. Beyea JA, Rosen E, Stephens T, Nguyen P, Hall SF. Audiometric
Testing Guideline Adherence in Children Undergoing Tympanostomy Tubes: A
Population-Based Study. Otolaryngol Head Neck Surg. 2018;158:1127-1133.

22. Hawker GA, Coyte PC, Wright JG, Paul JE, Bombardier C. Accuracy of
administrative data for assessing outcomes after knee replacement
surgery. J Clin Epidemiol. 1997;50:265-73.

23. Statistics Canada, Data, Non-emergency surgeries, by waiting times
(https://www150.statcan.gc.ca/t1/tbl1/en/tv.action?pid=1310048201\&pickMembers\%5B0\%5D=1.7).
Accessed June 22, 2020.

\textbf{Acknowledgements}

\begin{enumerate}
\tightlist
\item
  This study was supported by ICES, which is funded by an annual grant
  from the MOHLTC. The opinions, results and conclusions reported in
  this paper are those of the authors and are independent of the funding
  sources. No endorsements by ICES or the Ontario MOHLTC is intended or
  should be inferred.
\item
  The dataset was created at ICES Queen's (Kingston, Ontario). The
  dataset creation and data analysis were performed at ICES Queen's by
  Dr. Paul Nguyen.
\item
  Parts of this material are based on data and/or information compiled
  and provided by CIHI. However, the analyses, conclusions, opinions and
  statements expressed in the material are those of the author(s), and
  not necessarily those of CIHI.
\end{enumerate}

\textbf{Conflict of Interest}

\textbf{Role of Funders:} Financial support only.

\textbf{Conflict of Interest:} No conflicting relationships exist for
any author.

\textbf{Financial Disclosure:} No financial interests exist for any
author.

\textbf{Tables}

\textbf{Table 1.} Ontario Health Insurance Plan (OHIP) administrative
billing codes\selectlanguage{english}
\begin{longtable}[]{@{}ll@{}}
\toprule
\textbf{Description of Code} & \textbf{Billing Code}\tabularnewline
\midrule
\endhead
Anesthesia consult, repeat consult & A015, A016\tabularnewline
ASA III modifier & E022C\tabularnewline
ASA IV modifier & E017C\tabularnewline
ASA V modifier & E016C\tabularnewline
\bottomrule
\end{longtable}

ASA: American Society of Anesthesiologists Physical Status
Classification System

\textbf{Table 2.} American Society of Anesthesiologists (ASA) Physical
Status Classification System (Abouleish et al.2015)\textsuperscript{11}\selectlanguage{english}
\begin{longtable}[]{@{}lll@{}}
\toprule
\textbf{ASA Classification} & \textbf{Definition} & \textbf{Adult
Example}\tabularnewline
\midrule
\endhead
\textbf{ASA I} & A normal healthy patient & Healthy
non-smoker\tabularnewline
\textbf{ASA II} & Mild systemic disease & Well-controlled
hypertension\tabularnewline
\textbf{ASA III} & Severe systemic disease & Poorly controlled
diabetes\tabularnewline
\textbf{ASA IV} & Severe systemic disease that is a constant threat to
life & Myocardial infarction within the last 3 months\tabularnewline
\textbf{ASA V} & Moribund patient, not expected to survive without the
operation & Intracranial bleed with mass effect\tabularnewline
\bottomrule
\end{longtable}

\textbf{Table 3.} Most common surgical procedures of patients who
underwent a preoperative anesthesiology consultation\selectlanguage{english}
\begin{longtable}[]{@{}llll@{}}
\toprule
\textbf{Procedure} & \textbf{Percent of Total Procedures} &
\textbf{Relative Risk* (95\% CI) of ASA I-II Consult (vs. ASA III-V)} &
\textbf{P-Value}\tabularnewline
\midrule
\endhead
Knee, implantation of internal device & 9.46 & 0.711 (0.537-0.942) &
0.017\tabularnewline
Hip, implantation of internal device & 5.84 & 0.810 (0.613-1.072) &
0.140\tabularnewline
Cataract excision & 4.09 & 1.364 (1.025-1.814) & 0.033\tabularnewline
Repair, muscle of chest \& abdomen open approach & 3.31 & 0.745
(0.567-0.979) & 0.035\tabularnewline
Excision total, uterus & 2.76 & 1.109 (0.838-1.466) &
0.470\tabularnewline
Excision total, gallbladder & 2.67 & 0.879 (0.667-1.157) &
0.357\tabularnewline
Repair, knee joint arthroscopic approach & 1.95 & 0.999 (0.760-1.313) &
0.993\tabularnewline
Excision partial, bladder & 1.80 & 0.296 (0.083-1.059) &
0.061\tabularnewline
Coronary arteries bypass, open approach & 1.68 & 0.055 (0.042-0.071) &
\textless{}0.001\tabularnewline
Cesarean section & 1.62 & 1.300 (0.983-1.721) & 0.066\tabularnewline
\bottomrule
\end{longtable}

CI: Confidence interval

* Relative risks computed from modified Poisson regression models for
clustered data

\textbf{Figure Legends}

\textbf{Figure 1.} Preoperative anesthesiology consultations per year in
Ontario (2003-2017).

\textbf{Figure 2.} Outpatient anesthesiology consultations for patients
who did not proceed to a surgical procedure in the subsequent three
months.

\textbf{Figure 3.} Distribution of patients by ASA classification. ASA
class V represents \textless{}0.50\% of patients.

\textbf{Figure 4.} Percentage per year of patients who received
preoperative anesthesia consultation and were classified as ASA I or II
at the time of surgery.

\textbf{Figure 5.} Relative risk (with 95\% confidence limit bands) of
ASA I or II class patient (vs. ASA III-V) preoperative anesthesia
consultation versus surgeon age. Age 46-50 surgeon group is the
reference group.\selectlanguage{english}
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