PAUL F. WHITE
SOCIETY FOR AMBULATORY ANESTHESIA
Can the Iowa Satisfaction with Anesthesia Scale Be Used to
Measure Patient Satisfaction with Cataract Care Under
Topical Local Anesthesia and Monitored Sedation at a
Donald Fung, MD, MSc*, Marsha Cohen, MSc, MD†, Susan Stewart, MSc‡, and Andy Davies, MD*
*North Bay General Hospital, North Bay, and Department of Anesthesia, Faculty of Medicine, University of Toronto,
Toronto; †Centre for Research in Women’s Health, Sunnybrook & Women’s College Health Sciences Centre and the
Department of Health Policy, Management & Evaluation, University of Toronto, Toronto; and ‡North Shores District
Health Council, North Bay, Ontario, Canada
Patient satisfaction ratings provide a means to evaluate
were administered the ISAS along with alternate ratings
of quality of care and patient satisfaction. There were no
incomplete questionnaires. The ISAS demonstrated rea-
sonable reliability (Cronbach’s ? ? 0.68; test-retest ?
0.48–0.67). The ISAS had excellent construct validity;
ISAS scores were lower in patients who gave lower rat-
ings of quality (4.98 versus 5.64), who had lower satisfac-
tion visual analog scale scores (5.12 versus 5.65), who
wanted changes in their care (4.76 versus 5.67), who had
ferred more sedation (4.85 versus 5.66) (P ? 0.0001). Our
results indicate that the ISAS questionnaire is a feasible,
reliable, and valid tool to measure patient satisfaction in
patients undergoing cataract surgery under topical anes-
all cataract surgery to be conducted in an outpatient
setting using local anesthesia. Major medical complica-
tions to patients are rare; adverse events occur in about
hypertension (1). In the light of this safety, many centers
are reevaluating the rationale for costly intraoperative
care processes (such as the provision of monitored seda-
What outcomes can be used to track the impact of these
changes on the quality of cataract care?
ataract surgery is the most common operation
performed in the elderly, with more than 1.3 mil-
lion cases per year in the United States alone (1,2).
Patient satisfaction ratings provide a means to eval-
uate and monitor quality of health care (6), especially
in settings where adverse events are rare. Investiga-
tors have used simple ratings of patient satisfaction to
assess the quality of their cataract care (7,8) or to
evaluate specific components of that care (9–12).
However, simple ratings of patient satisfaction can
often be imprecise (13–15) or may not be measuring
satisfaction at all (16). Ratings of patient satisfaction
must show that they yield the same score if conditions
remain the same (i.e., the measurement is reliable) and
that they truly reflect patients’ satisfaction with their
care and not just a feeling of gratitude or relief (i.e., the
measurement must be valid) (6).
In 1997, Dexter et al. (13) developed the Iowa Satisfac-
tion with Anesthesia Scale (ISAS) comprised of 11 items.
Their scale exhibited good reliability and validity when
applied to outpatients undergoing a variety of proce-
dures under monitored care at a tertiary care setting.
However, this questionnaire has yet to be tested in com-
munity hospitals or on cataract patients alone.
The purpose of this study was to evaluate the ISAS
as a patient satisfaction questionnaire in the cataract
This study was funded by a grant from the Physicians’ Services
All authors contributed significantly to the analysis of data and
the preparation of the manuscript.
Accepted for publication December 8, 2004.
Address correspondence and reprint requests to Donald Fung,
MD, MSc, North Bay General Hospital, 750 Scollard, North Bay,
Ontario, Canada. Address e-mail to firstname.lastname@example.org.
©2005 by the International Anesthesia Research Society
0003-2999/05Anesth Analg 2005;100:1637–43
clinic of a small community hospital in Northeastern
Ontario, Canada. We hoped to establish whether the
ISAS could be feasibly administered and to examine
its reliability and validity when applied exclusively to
patients undergoing cataract excision and lens im-
plantation under topical local anesthesia with moni-
tored sedation care given by an anesthesiologist.
The study was approved by the Ethics Committee of
the North Bay General Hospital.
Cataract care at the North Bay General Hospital is
conducted in a clinic location separate from the main
operating room. An anesthesiologist assesses each pa-
tient and administers IV sedation as needed while
monitoring vital signs during the procedure. All pa-
tients receive topical intraocular local anesthesia. After
the operation, patients recover under the care of a
nurse and are discharged home as soon as they have
met standard discharge criteria (Aldrete score of 10
with minimal pain and nausea).
The ISAS is a written questionnaire consisting of 11
items (Appendix 1). Three items ask patients to rate
their pain. Despite their similar wording, these ques-
tions tap different aspects of the patient’s experience
(13). Six items ask patients to report on what else they
may have felt during their anesthetic experience. Two
items ask patients to directly rate their anesthetic ex-
perience. Each item uses the same six-point response
format (disagree very much, disagree moderately, dis-
agree slightly, agree slightly, agree moderately, agree
very much) scored from ?1 to ?6 (where appropriate,
scores of negatively worded items were reversed). The
best possible score for each item is 6 and the final
questionnaire score is reported as the mean score of all
11 items (max score ? 6).
We obtained permission to use the scale from the
original author. We preserved the original wording of
the questionnaire instructions and all items and re-
sponse sets. The questionnaire was formatted on
single-sided paper in 16-pt font. The instructions were
written on the first page followed by the questionnaire
presented as two questions per page.
Five additional items were added to the end of the
questionnaire that served as validity indicators for
the ISAS. These included: 1. the degree of agreement
to the statement, “There is nothing I would change
in the care I just received”; 2. an evaluation of the
quality of their intraoperative care on a scale of 1 to
6; 3. any advice that would make their care better;
4. a patient satisfaction rating (visual analog scale
[VAS] score from 1 to 10); and 5. preference for
more, the same, less, or no sedation if they were to
have the operation again.
A pretest of this questionnaire was conducted on 10
patients. This pretest indicated that patients needed
help in filling out this questionnaire because of infir-
mity of advanced age, blurred vision from the surgery,
pain and discomfort, or the lingering effects of seda-
tion. As a result, we chose to make the questionnaire
either self-administered or interviewer-administered
(SS) according to the preference of the patient.
We recruited every patient arriving for surgery on
2 days per week when a research assistant was avail-
able. We excluded patients who were non-English
speaking, had psychiatric or mental incapacity (inabil-
ity to provide consent), required general anesthesia, or
who refused to participate. The two ophthalmologists,
five (of eight) anesthesiologists, and all nursing staff
agreed to participate. The manner of sedation was
decided by each anesthesiologist.
All patients meeting inclusion criteria were asked to
provide consent. Demographic information was gath-
ered in a brief preoperative interview. Immediately
after surgery, the anesthesiologist and circulating
nurse were asked to complete the ISAS according to
how they thought the patient would answer it. As the
patient readied him/herself for discharge, he/she was
asked to complete the ISAS. The time required to
complete the questionnaire was recorded. The same
research assistant (SS) collected all data and adminis-
tered the questionnaire to all patients.
A sample size of 300 was chosen to allow multivari-
able regression analysis (17,18). We also based our sam-
ple size on the reported standard deviation of the ISAS
of 0.87 (o ´ ? 0.09) (13). A sample size of 300 allowed the
ISAS score determined for all cataract patients to have a
95% confidence limit interval of 0.02.
First, to establish feasibility, the participation rate was
tracked (patients who agreed to complete the question-
naire divided by the total patients asked to participate).
Second, questionnaire response rate was measured: the
proportion of completed ISAS questionnaires less the
number of incomplete or illegible questionnaires and
missing items over all questionnaires. Third, the average
time to complete the questionnaire as well as the pro-
portion of patients who required assistance were re-
corded. Finally, we estimated the cost of each question-
naire (printing costs and interviewer costs).
The internal consistency of the items of the ISAS
(whether they were all measuring the same thing) was
estimated using Cronbach’s ?. To obtain estimates of
test-retest reliability, 26 patients were administered
the questionnaire twice; a Spearman correlation coef-
ficient, intraclass correlation coefficient, and the
weighted kappa between first and second question-
naire scores were calculated. The latter two statistics
measured the concordance between the two ratings.
Construct validity of the ISAS was assessed in sev-
eral ways. One, the patient’s ISAS score was correlated
with that predicted by their anesthesiologist and cir-
culating nurse. Two, the overall ISAS score (corrected
to exclude that item’s score) was correlated with its
APPLYING THE ISAS TO MONITORED CATARACT CARE
FUNG ET AL. ANESTH ANALG
own two single item ratings of global satisfaction
(item 2: “I would have the same anesthetic,” and item
8: “I was satisfied with my anesthesia care”) as well as
the satisfaction VAS score. Three, the ISAS score was
correlated with alternate ratings of the overall quality
of care; a single item evaluative rating of quality of
care and a single rating on whether they agreed with
the statement: “There was nothing I would change in
the care I just received.”
As an additional measure of construct validity,
we evaluated the ability of the ISAS to discriminate
appropriately between patient groups. We exam-
ined the ability of the ISAS to predict patients who
had higher ratings of satisfaction or quality, who wanted
the next time.
All scores on ISAS and patient ratings were re-
ported as means (standard deviation). Cronbach’s ?,
Spearman, weighted kappa, and intraclass correlation
coefficients were used as statistics of reliability; Spear-
man, Pearson, and Kendall’s tau b correlation coeffi-
cients as statistics of validity. Two-tailed unpaired
t-tests for tests of significance between patient groups
were used where necessary to establish discriminant
validity (i.e., differences in mean ISAS scores in pa-
tients who rated the quality of their experience as ?6).
P ? 0.05 was used as the level of significance. All
statistics were calculated using STATA.
We postulated the following a priori criteria that
would indicate that the ISAS had achieved acceptable
standards as a reliable and valid questionnaire. Cron-
bach’s ? was expected to exceed 0.6 to allow group
comparisons (17). Test-retest reliability and correla-
tions with alternate measures of satisfaction (construct
validity) were also expected to exceed 0.5.
We approached 366 patients arriving for surgery be-
tween January and May 2003. Thirty-eight patients
were excluded because of language, communication
difficulties, or mental illness; 22 did not participate (12
felt too rushed; 10 refused). Thus, 306 patients were
included in the study.
Seventy percent of all patients were between 60 and
80 yr of age (Table 1); there were slightly more men
than women. Most patients were Canadian born, 70%
spoke English as a first language, and 70% had at least
a high school education. Ninety percent of patients
were ASA physical status score II or III and, of these,
the majority had hypertension, diabetes, and/or heart
disease. Forty percent of patients were undergoing
cataract surgery on their second eye.
Participation rate was 93% (306 of 328 patients). We
obtained complete ISAS questionnaires from all 306
patients who agreed to participate and there were no
incomplete questionnaires. The average time to com-
plete the questionnaire was 5.3 min (sd ? 1.37).
Eighty-one percent of patients required assistance
with completing the questionnaire. If the clinic clerical
staff assumed the duties of assisting in all question-
naires (at $25.00/hour) and each questionnaire cost
$0.60, the cost of each questionnaire can be estimated
as $2.80 (Canadian dollars).
The mean ISAS score for all patients was 5.60 (sd ?
0.48) and the median score was 5.73 (range, 3.3–6.0).
The statistic of skewness of 1.56 and a kurtosis 5.65
indicated that the data were not normally distributed.
The single item quality of care rating (“Looking back
on my surgery, I would say the quality of the experi-
ence was poor . . . perfect”) had lower mean score
(5.1), better variability (sd ? .89), and also had better
statistics of normality (skewness 0.73; kurtosis 2.72)
compared with the mean ISAS score. The other four
single item ratings were substantially more skewed
compared with the ISAS.
Using responses from 306 patients, the coefficient ?
for the ISAS was 0.68. Removing the contribution of 1
or more items to the ISAS score only served to increase
? to a maximum of 0.73 (data not shown).
Test-retest reliability was obtained from 26 patients
who were administered the ISAS. The average time
between these 2 occasions was 4 h (range, 3–9 h). The
Spearman correlation, weighted kappa, and intraclass
correlation coefficient between the mean ISAS score
on the two occasions were 0.67, 0.48, and 0.57, respec-
tively (indicating moderate reliability) (19). Test-retest
reliability of three alternate single item ratings of qual-
ity and satisfaction was also measured. The two items
within the ISAS (items 2 and 8) that directly rated
anesthetic care and quality of care yielded Spearman
correlations (weighted kappa, intraclass correlation
coefficient) of 0.51 (0.50, 0.53) and 0.0 (0.0, 0.0), respec-
tively. The item asking patients to rate overall quality
of their care on a 6-point scale had a test-retest reli-
ability of 0.66 (0.45, 0.52). Thus, the test-retest reliabil-
ity of the ISAS was equal or superior to single item
alternate ratings of quality and satisfaction.
Correlational (“criterion”) validity (i.e., correlations
between the ISAS and alternative ratings of patient
care) were poor to fair (Table 2). ISAS scores did not
correlate with the anesthesiologists’ or nurses’ ratings
of the ISAS (Spearman rho ? 0.00 and 0.11). Correla-
tions of the ISAS score with the patient’s VAS score of
satisfaction, or with whether patients wanted the same
anesthetic again, or with 2 single item ratings of the
quality of care were fair (rho ? 0.24–0.35). The ISAS
did not correlate with whether a patient had any sug-
gestions to improve their care (rho ? ?0.14). It had
moderate correlations with whether a patient agreed
that there was nothing in their care that they would
change (rho ? 0.39).
APPLYING THE ISAS TO MONITORED CATARACT CARE
FUNG ET AL.
The ISAS had excellent construct validity. When
patients were dichotomized into groups based on high
or low ratings on alternate measures of patient satis-
faction or quality, the ISAS score matched these rat-
ings. Furthermore, the ISAS was higher in patients
who had higher ratings on these scales (Table 3). For
example, patients who had scored ?90% on their VAS
satisfaction scale had significantly lower scores on
their ISAS: 5.34 versus 5.67 (P ? 0.0001), and this
difference increased in patients who scored ?80% on
the satisfaction VAS: 5.12 versus 5.64 (P ? 0.0001).
Similarly, patients who rated their quality of care as 5
or less on the 6-point evaluative scale score, had lower
ISAS: 5.32 versus 5.68 (P ? 0.0001), and this difference
was greater in those patients who rated their quality
poorer (4 or less): ISAS 4.98 versus 5.64 (P ? 0.0001).
The ISAS also demonstrated construct validity by dis-
tinguishing appropriately between patient responses on
alternate ratings of quality of care (Table 3). ISAS scores
were significantly lower for patients who did not
strongly agree with the statement, “There is nothing I
would change in the care I just received” compared with
those that strongly agreed with that statement: 4.76 ver-
sus 5.67 (P ? 0.0001). There were also significant differ-
ences in ISAS scores in patients who had any advice or
suggestions to assist future care of patients (5.08 versus
5.63, P ? 0.0001) and in patients who wanted more
sedation if they were to have the same surgery again
(4.85 versus 5.66, P ? 0.0001).
We have shown that the ISAS questionnaire is a
feasible, reliable, and valid tool for measuring pa-
tient satisfaction in patients undergoing cataract
Table 1. Patient Demographics
Mean (sd) ? 71.6 (9.8)
Previous eye surgery
Country of Birth
Beyond high school
Declined to answer or did not know
ASA physical status score
Premorbid medical conditions
APPLYING THE ISAS TO MONITORED CATARACT CARE
FUNG ET AL. ANESTH ANALG
surgery with monitored care in a community hos-
pital. Summed scores from the ISAS have sufficient
reliability to allow group comparisons. In addition,
the ISAS has excellent construct validity; mean ISAS
scores were lower in patients who had less than
perfect alternate ratings of quality and satisfaction.
In 1999, Dexter et al. (13) used psychometric tech-
niques to develop the ISAS to measure patient satisfac-
tion with monitored anesthesia care. To ensure content
validity, items were suggested by staff (anesthesiolo-
gists, nurses, and administrators) and ratified with
patients. When self-administered on 92 patients un-
dergoing various outpatient procedures (53% un-
dergoing cataract care) at a tertiary care center, they
had a response rate of 82%. Patient responses to the
ISAS demonstrated excellent reliability; ? ? 0.8; rsq
(test-retest) ? 0.74. There was also reasonable evi-
dence of validity; correlations with provider ratings
were good (rsq ? 0.23) as were correlations with a
single item rating of satisfaction (tau ? 0.41). They
proposed that this scale could be useful to assess the
satisfaction of patients of their monitored anesthesia
care or even in patients after general anesthesia.
Psychometricians, however, warn that question-
naire instruments may not retain their feasibility, re-
liability, and validity and should be retested when
applied to different settings or circumstances (17).
Therefore, we thought it necessary to establish that the
ISAS retained its measurement properties when ap-
plied to cataract care exclusively in a Canadian com-
munity hospital. We also expanded on Dexter et al.’s
original finding by confirming that the ISAS could
Table 2. Correlational Validity of Iowa Satisfaction with Anesthesia Scale (ISAS) Against Single Item Ratings of
Anesthesiologists ? ISAS
Nurses ? ISAS
Item 2: “I would have the same anesthetic again”
Item 8: “I was satisfied with my anesthetic care”
Changes in care?
Kendall’s tau b
Patient ISAS (corrected)a
VAS ? visual analog scale.
aPatient mean ISAS score excluding that item.
Table 3. Relationship Between Iowa Satisfaction with Anesthesia (ISAS) Scores and Other Questions on Satisfaction/
Quality of Anesthetic Experience
Looking back on my surgery, I would say the quality of the experience was:
5 or 6
4 or less
5 or less
How satisfied were you with the care you just received?
There is nothing I would change about the care I just received.
Based on your experience today, what advice or suggestions do you have that
can help us care for future patients?
During your operation, your anesthesiologist gave you IV medication to make
you feel more calm, relaxed, and/or sleepy. If you were to have this type
of surgery again, would you prefer
APPLYING THE ISAS TO MONITORED CATARACT CARE
FUNG ET AL.