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ABSTRACT:
Introduction: The ASA PS Classification System is widely used to assess
patients preoperatively. Objective: To assess inter-rater consistency of PS
determination between surgical and anesthesiologist residents, to find sources of
variability, to evaluate the effect of an interdepartmental re-orientation meeting,
and to determine effects of discordance on patient outcome. Methods: A case
series of all inpatient operations under anesthesia other than local in 2004. An
interdepartmental meeting on was held towards the end of the 3rd month of the 9month duration of the study. Results: Of 1590 cases, almost all of the 62
percent discordance was where a higher PS class was assigned by the
anesthesiologist-in-charge. After the conference, discordance rate decreased
from 71 to 57 percent. Neither emergent/elective classification of operations nor
years of practicing of the residents-in-charge showed correlation with
discordance rates. Despite the disconcordance, there was no significant effect
on mortality and morbidity. A gradual deterioration back towards pre-conference
discordance rates suggests the need for regular orientations. Future research is
recommended to determine the significance of the documented variability in
terms of preoperative laboratory usage.
Keywords: ASA PS, physical status, functional status, preoperative evaluation
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Introduction:
The American Society of Anesthesiologists (ASA) Physical Status (PS)
Classification Scale is used by anesthesiologists and recognized by surgeons
globally 1,2,3 as a most practical way to assess the preoperative PS of patients. It
has at least equal prognostic significance as other preoperative classification
systems.2
In 2001, when the Departments of Surgery and Anesthesiology of Hospital
X decided to do away with routine cardiopulmonary, endocrine, and pediatric
clearances prior to operations, they mutually agreed that aside from the selective
use of preoperative screening examinations, the physical status of the patients
should be routinely assessed using ASA PS classification. They would use the
PS categorization to facilitate discussion, problem solving and decision making
during the preoperative, postoperative, and mortality and morbidity conferences.
Specifically, the PS categorization would be used to assess the preoperative risk,
to identify patients who might need more attention and preoperative preparations,
to facilitate analysis and understanding of complications, as well as to facilitate in
quality service review. From 2001 to this writing, September, 2004, the PS
categorization of all preoperative patients of the Department of Surgery was
being done by both surgical and anesthesiologist residents. During the weekly
Surgery-Anesthesiology Conferences, questions would be raised by both
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consultants and residents of the two departments on the accuracy and
discrepancy of the posted PS categorizations.
In March 2004, because of the persistent questionings on the reliability of
interpretations of PS between surgeons and anesthesiologists, it was decided to
formally conduct a study. In late March, 2004 a joint Surgery-Anesthesiology
Conference re-oriented all residents on the ASA PS Classification Scale with
some agreements on how to deal with commonly encountered issues such as
age, previously controlled medical conditions, tuberculosis, etc. It was also
decided to make a study on the extent of variability.
The objectives of this study were to assess inter-rater consistency of
preoperative physical status determination between surgeons and
anesthesiologists in a tertiary hospital in the Philippines; to find possible sources
of this variability; to evaluate the effect of a Surgery-Anesthesia
interdepartmental meeting on these discordance rates; and to determine if poor
patient outcome was associated with a higher discordance.
Methods:
This is a case series of all patients who underwent inpatient operations
under anesthesia other than local at Hospital X, a tertiary city government
hospital in the Philippines between January 2004 and September 2004.
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A Surgery-Anesthesia interdepartmental meeting on ASA PS classification
held at the last week of March aimed to reorient the residents and improve
discordance rates.
Results:
Of the 1680 operative records during the 9 months covered by the study,
1590 (87 percent) had documentation of PS status by both surgeons and
anesthesiologists. Inter-observer PS assigned was more often than not (62
percent) different between the two physicians (anesthesiologist-in-charge, and
surgeon-in-charge) most directly involved with the patient. Almost all of the
discordance was where anesthesia assigned the patient to a higher PS status, 3
percent of which was by two levels. Less than one percent was assigned higher
PS by the surgeon.
A Surgery-Anesthesia interdepartmental meeting on ASA PS classification
led to the Department of Anesthesia initiating their mandatory use of a formal
preoperative evaluation form. A pre-conference discordance rate of 71%
(365/515) improved to 57% (552/974).
5
Monthly variability was graphically illustrated according to elective/
emergency nature (figure 1) of the operations and according to year level of
training of the involved resident (figures 2 and 3).
Of the 61 mortalities and 47 morbidities reported during the duration of the
study, anesthesia other than local were used on 40 postoperative mortalities and
41 perioperative morbidities. 92 and 93 percent of these had PS data from both
Anesthesia and Surgery. The discordance rates were 62 and 68 respectively,
compared with the overall average discordance rate of 62%.
Discussion:
Preoperative risk assessment of patients aims to minimize postoperative
complications and adverse outcomes. A complete clinical risk assessment
should include not only history and physical examination but also a complete
review of systems, medication history, and functional status evaluation. The
general public agrees 4 with physicians that such forms an important part of
preparations prior to surgery. There is however no standard scoring system or
definite way of determining which signs, symptoms, or laboratory examinations
hold greater weight. The ASA PS Classification System, is one of the most
popular 1,2,3 system being utilized by surgeons and anesthesiologists. It gives a
global assessment of risk in contrast with specific organ-system risk scales.
Inter-rater agreement between surgeons and anesthesiologists, and even among
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anesthesiologists themselves 5,6,7 however varies tremendously, as was
observed in our institution.
The high overall discordance rate of 62% during the period covered by this
study suggests a need to improve the scoring system or the system of its
application. It can be seen that ASA used open-ended criteria such as mild,
some, moderate, severe, moribund, and may be a reason for the continuing
discrepancy.
PS
Systemic disease
AND
Functional limitation
1
Normal
2
Mild to moderate
None
3
Severe
Some
4
Life-threatening ± sx
Incapacitated
5
Moribund (sx last resort)
6
Brain dead donor
The emergent or elective classification of the operations had no effect on
the discrepancy rate. Years of practicing (3-year anesthesia training program, 5year surgery training program) also did not show a correlation with scoring.
After the conference, the resulting improvement of inter-observer
consistency from 29 to 43 percent (and above 50 in the immediate postconference period) suggests the need for orienting surgical and anesthesia
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residents to the system of classification. The gradual deterioration back towards
pre-conference values suggests a need to do orientation activities regularly,
perhaps once or twice a year. First year surgical residents showed a tendency to
forget the orientation quickly.
Previous local data 8 shows ASA class II patients having a higher risk than
those described in other countries. Since much of the increase/ discordance in
this study was in class II patients, it is important to determine if the outcome
varied. The PS discordance rates of the postoperative mortalities and
perioperative morbidities were 62% and 68% respectively, showing no difference
with the overall average discordance rate of 62%.
Data completion remains a problem, with many charts not documenting
PS classifications assigned in weekly audits. The Department of Anesthesia
initiated a mandatory use of a formal preoperative evaluation form after the joint
conference. Data does not show an effect on increasing concordance. Some
foreign data suggest that introduction of a structured form for ASA might even
lower data completion due to changes in routines and layouts.9 Patient education
has limited the feasibility of a self-administered health status questionnaire
reduce the need for prolonged physician evaluation time.
Future research objectives include finding other possible sources of
discordance; determining effects in subsequent ordering for laboratory
10
to
8
examinations and mandatory preoperative medical evaluation by internists/
cardiologists; and quantifying the impact of the differences in laboratory
examinations.
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REFERENCES:
1Aronson
WL; McAuliffe MS; Miller K. Variability in the American Society of
Anesthesiologists Physical Status Classification Scale. AANA J 2003; 71(4):
265-74.
2Junger
A; Engel J; Quinzio L; Banzhaf A; Jost A; Hempelmann G. Risk
predictors, scoring systems and prognostic models in anesthesia and intensive
care. Part I: anesthesia. Anasthesiol Intensivmed Notfallmed Schmerzther 2002;
37(9): 520-7.
3Meftahuzzaman
AM; Rickta D; Sarker SC; MMC, Mymensingh. Grading &
scoring systems used for pre-anaesthetic evaluation of the patients.
Mymensingh Med J 2002; 11(1): 44-8.
4Matthey
P; Finucane BT; Finegan BA. The attitude of the general public
towards preoperative assessment and risks associated with general anesthesia.
Can J Anaesth 2001; 48(4): 333-9.
5Haynes
SR; Lawler PG. An assessment of the consistency of ASA physical
status classification allocation. Anaesthesia 1995; 50(3): 195-9.
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6Mak
PH; Campbell RC; Irwin MG. The ASA Physical Status Classification: inter-
observer consistency. American Society of Anesthesiologists. Anaesth Intensive
Care 2002; 30(5): 633-40.
7Owens
WD, Felts JA, Spitznagel EL Jr. ASA physical status classifications: a
study of consistency of ratings. Anesthesiology 1978; 49(4): 239-43.
8Samar-Sy
OM; Bautista AH; Leachon AC; Dans AL; Tamesis BR. Preoperative
predictors of complications among Filipinos undergoing non-cardiac surgery in a
tertiary general hospital. Philipp J Intern Med. 1995; 33(5):163-176.
9Marco
AP; Buchman D; Lancz C. Influence of form structure on the anesthesia
preoperative evaluation. J Clin Anesth 2003; 15(6): 411-7.
10Reeves
SW; Tielsch JM; Katz J; Bass EB; Schein OD. A self-administered
health questionnaire for the preoperative risk stratification of patients undergoing
cataract surgery. Am J Ophthalmol 2003; 135(5): 599-606.
11Pollard
JB; Garnerin P. Outpatient preoperative evaluation clinic can lead to a
rapid shift from inpatient to outpatient surgery: a retrospective review of
perioperative setting and outcome. J Clin Anesth 1999; 11(1): 39-45.
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Figure 1
Variability of Assigned Physical Status
90%
Discordance Rate
80%
70%
60%
50%
Elective OR
Emergency OR
40%
30%
20%
10%
0%
Jan
Feb
Mar
Apr
May
2004
Jun
Jul
Aug
Sep
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Figure 2
Discordance by Level of Surgical
Training
90%
Discordance Rate
80%
70%
Residency
60%
first year
50%
second year
40%
third year
fourth year
30%
fifth year
20%
10%
0%
Jan
Feb
Mar
Apr
May
2004
Jun
Jul
Aug
Sep
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Figure 3
Discordance by Level of Anesthesia
Training
1
0.9
Discordance Rate
0.8
0.7
Residency
0.6
first year
0.5
second year
0.4
third year
0.3
0.2
0.1
0
Jan
Feb
Mar
Apr
May
2004
Jun
Jul
Aug
Sep