British Journal of Anaesthesia 110 (5): 780–7 (2013)
Advance Access publication 5 February 2013 . doi:10.1093/bja/aes517
OBSTETRICS
Pain vs comfort scores after Caesarean section: a randomized
trial
C. S. L. Chooi1,2, A. M. White 2, S. G. M. Tan 4, K. Dowling 3 and A. M. Cyna 1,2*
1
University of Adelaide, Adelaide, Australia
Department of Women’s Anaesthesia and 3 Department of Public Health, Women’s and Children’s Hospital, 72 King William Road,
Adelaide, SA 5006, Australia
4
Nepean Hospital, Derby St, Kingswood, NSW 2747, Australia
2
* Corresponding author. E-mail [email protected]
Editor’s key points
† Accurate pain
assessment can allow the
optimization of
postoperative analgesia.
† The words used by staff
to question patients may
alter the pain experience.
† Using a structured
approach, the effect of
questioning patients
about their pain was
investigated.
† Direct questioning and
rating of pain may
adversely affect pain and
patient perception of
recovery.
† The words used by staff
after operation may alter
the pain experience for
patients.
Background. The use of negative words, such as ‘sting’ and ‘pain’, can increase patient pain
and anxiety. We aimed to determine how pain scores compare with comfort scores and
how the technique of pain assessment affects patient perceptions and experiences after
operation.
Methods. After Caesarean section, 300 women were randomized before post-anaesthesia
review. Group P women were asked to rate their pain on a 0–10-point verbal numerical
rating scale (VNRS), where ‘0’ was ‘no pain’ and ‘10’ was ‘worst pain imaginable’. Group C
women were asked to rate comfort on a 0–10-point VNRS, where ‘0’ was ‘no comfort’
and ‘10’ was ‘most comfortable’. All women were asked whether the Caesarean wound
was bothersome, unpleasant, associated with tissue damage, and whether additional
analgesia was desired.
Results. The median (inter-quartile range) VNRS pain scores was higher than inverted
comfort scores at rest, 2 (1, 4) vs 2 (0.5, 3), P¼0.001, and movement, 6 (4, 7) vs 4 (3, 5),
P,0.001. Group P women were more likely to be bothered by their Caesarean section,
had greater VNRS ‘Bother’ scores, 4 (2, 6) vs 1 (0, 3), P,0.001, perceived postoperative
sensations as ‘unpleasant’ [relative risk (RR) 3.05, 95% confidence interval (CI) 2.20,
4.23], P,0.001, and related to tissue damage rather than healing and recovery (RR 2.03,
95% CI 1.30, 3.18), P¼0.001. Group P women were also more likely to request additional
analgesia (RR 4.33, 95% CI 1.84, 10.22), P,0.001.
Conclusions. Asking about pain and pain scores after Caesarean section adversely affects
patient reports of their postoperative experiences.
Keywords: communication;
unconscious perception
measurement;
pain
scores;
psychological
responses;
Accepted for publication: 31 October 2012
Recent studies have shown that the way healthcare workers
(HCWs) communicate with patients can suggest perceptual
experiences that can increase anxiety and pain.1 2 In the first
randomized study investigating the effects of communication
before a potentially painful procedure, participants were more
likely to vocalize pain during i.v. cannula insertion where a
negative suggestion was given.3 Similarly, in a well-designed,
double-blind, randomized controlled trial of 140 women receiving spinal anaesthesia for Caesarean section or epidural analgesia for labour, those participants who were warned of a
‘big bee sting’ before local anaesthetic infiltration had higher
pain scores than those informed that the anaesthetist was
‘numbing the area’.2 The word ‘nocebo’ has been coined to describe non-pharmacological adverse effects of an intervention
similar, but opposite, to the ‘placebo’ effect.4 – 6
Advances in brain imaging have led to further understanding of the neurobiology of this phenomenon where the anterior cingulate cortex, which links the limbic system with the
sensory cortex, appears to be modulated when a negative
suggestion is given.7 8 It appears that a sensation can be
associated and perceived as suffering, or not, dependent
on the words used.
The International Association for the Study of Pain (IASP)
defines pain as, ‘an unpleasant sensory and emotional
& The Author [2013]. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved.
For Permissions, please email: [email protected]
Pain vs comfort scores after Caesarean section
experience associated with actual or potential tissue
damage, or described in terms of such damage’.9 According
to this definition, the word ‘pain’ may function as a negative
suggestion or nocebo communication which elicits a subconscious change in a patient’s mood, perception, or behaviour.10 Therefore, the assessment of postoperative pain
using negatively valenced,1 nocebo2 communications might
be expected to adversely affect patient perceptions of their
postoperative experience.
Postoperative pain management is said to require accurate and reliable methods of assessment performed on a
regular and ongoing basis.11 Although multiple outcome
measures are required to adequately capture the complexity
of the pain experience, in clinical practice, the assessment of
pain typically uses simple scales such as the visual analogue
scale (VAS) score or verbal numerical rating score (VNRS).12 13
In the postoperative setting, the functional capacity of the
patient may also be assessed using the VAS for pain at rest
(static) and movement (dynamic).14 The VNRS and VAS are
widely used and have been found to correlate well with
each other in a number of studies.11 In our institution on
the post-anaesthetic ward round, healthcare providers
usually ask patients ‘Do you have pain?’ and then ask for a
rating of their pain using a verbal numerical rating scale
(VNRS). These communications attempt to ensure patients
receive adequate analgesia. However, the use of the negative
word ‘pain’ may actually be causing patients to focus on their
pain and interpret normal healing sensations as pain when
this might not be the case with neutral or more positive language.1 2 Our anecdotal experience, and a previous study,
has suggested that the use of the word ‘comfort’ rather
than the word ‘pain’ may affect patients’ experience of
their recovery.15 The aim of this study was to investigate
how standard pain scores compare with comfort scores
after Caesarean section and determine whether the way
pain is assessed affects patient reports of their perceptions
and experiences after operation.
Methods
After local Human Research Ethics Committee (LHREC) approval and trial registration (ANZCTR No: 12610000890033),
337 women presenting for routine anaesthetic follow-up
after Caesarean section, between November 2010 and September 2011, in the largest tertiary referral centre for maternity care in South Australia were considered for eligibility. We
excluded those who were not English speaking or who
needed an interpreter, patients under 18 yr of age, and
those who were deaf, had an intellectual disability, or had
a history of chronic pain or opiate abuse. Two researchers
(C.S.L.C., A.M.W.) were involved in eligibility assessments
and interviewing women after their Caesarean section. The
researchers worked independently in assessing the women,
and for the purposes of this study. Each woman was
assessed and interviewed by one of the researchers
(C.S.L.C., A.M.W.) between 10 and 36 h after operation. All eligible patients had patient characteristic data recorded before
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being randomized prospectively, into either having their pain
assessed using standard pain scores (Group P) or comfort
scores (Group C), within 5 min of their planned postoperative
research assessment. The randomization sequence was
computer-generated in blocks of unspecified size in a 1:1
ratio to give a parallel group design. Allocation concealment
was ensured by using consecutively numbered, opaque
sealed envelopes. Subjects were blinded to group allocation,
by being unaware of the nature of the intervention, but
assessors were not. Written informed patient consent to
take part in the study was obtained after the postoperative
questioning was completed. Where informed patient
consent was not obtained, responses were recorded in the
case notes and acted upon as per usual care, without including the patient data in the study. The assessment of pain or
comfort was performed in addition to our routine postanaesthesia rounds.
After initial introductions, two types of questioning, frequently used by anaesthetists in our institution, were used
to assess pain after Caesarean section (Table 1). Group P
patients were asked the structured question, ‘You have had
a Caesarean section and I am interested in your pain from
the surgical trauma. So, is it okay if I ask you some questions
about your pain?’ Women were then asked, ‘Do you have any
pain?’ If the presence of pain was confirmed, patients were
asked for the location of their pain. Women were then
asked to quantify their postoperative pain, at rest and with
movement, on a 0–10-point VNRS, where ‘0’ was ‘no pain’
and ‘10’ was ‘the worst pain imaginable’. A VAS was also
used, where one end of the scale was marked, ‘least pain’
and the other, ‘most pain’. On the reverse side of the VAS
was a 0– 100 mm scale (Fig. 1A). Women were then asked
‘Does the wound bother you?’, ‘How much does it bother
you, where “0” is no bother and “10” is the most bothersome
imaginable?’, ‘Are you comfortable?’, and ‘Would you like
additional pain relief?’
Women in Group C were asked the structured question,
‘You have had your Caesarean section, your wound is
healing and you’re in the process of recovery. Is it okay if I
ask you some questions about your level of comfort?’, followed by ‘Are you comfortable?’ The researcher documented
any reason for discomfort. They were then asked, for both at
rest and on movement, ‘Can you rate your comfort level
where, “10” is the most comfortable and, “0” is the least comfortable?’ They were then asked to quantify their comfort level
on a VAS, where one end of the scale was marked as ‘most
comfort’ and the other end was marked ‘least comfort’. On
the reverse side of the VAS was a 0–100 mm scale (Fig. 1B).
Women were also asked ‘Does the healing wound bother
you?’, ‘How much does it bother you, where “0” is no bother
and “10” is the most bothersome imaginable?’, ‘Do you have
pain?’, and ‘Would you like additional analgesia?’
All women were asked: ‘Do you think that the sensations
that you have had after your operation to be unpleasant or
not particularly unpleasant?’, ‘Do you prefer to be asked
about your comfort level or your pain level, and why?’
Lastly, study participants were asked, ‘Do you think of the
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Chooi et al.
Table 1 Interview questions for Group P (pain scores) and Group C
(comfort scores). VNRS, verbal numerical rating scores; VAS, visual
analogue scores
Group P
Group C
‘You have had a Caesarean
section and I am interested in
your pain from the surgical
trauma. So, is it okay if I ask you
some questions about your
pain?’
‘You have had you Caesarean
section, your wound is healing
and you are in the process of
recovery. Is it okay if I ask you
some questions about your
level of comfort?’
‘Do you have any pain?’
‘Are you comfortable?’
VNRS for pain where 0, no pain;
10, worst pain imaginable
At rest
On movement
VNRS for comfort where 0, no
comfort; 10, most comfort
At rest
On movement
VAS for pain where one end is
marked ‘least pain’ and other is
‘most pain’
At rest
On movement
VAS for comfort where one end
is marked ‘least comfort’ and
the other ‘most comfort’
At rest
On movement
‘Does the wound bother you?’
‘Does the healing wound
bother you?’
‘How much does it bother you
where 0 is no bother and 10 is
the most bothersome
imaginable?’
‘How much does it bother you
where 0 is no bother and 10 is
the most bothersome
imaginable?’
‘Are you comfortable?’
‘Do you have any pain?’
‘Would you like additional pain
relief?’
‘Would you like additional
analgesia?’
All women were asked
‘Do you think that the
sensation that you have had
after your operation to be
unpleasant or not particularly
unpleasant?’
‘Do you prefer to be asked
about your comfort level or
your pain level?’
‘Do you think the sensations
after your operation to be
that of injury and disability or
healing and recovery?’
sensations after your operation to be that of “tissue damage”
or “healing and recovery”?’. These questions were asked with
the options presented in a computer-generated randomized
sequence stratified according to Group P or C. For example,
half the women in Group P and half the women in Group C
were either asked whether they found the ‘. . . sensations to
be those of tissue damage or healing and recovery’ or ‘. . .
sensations to be those of healing and recovery or tissue
damage?’ (Table 1).
Our primary outcome was to assess pain severity as measured by a 0–10-point VNRS for pain compared with an
equivalent inverted VNRS for comfort. Our secondary outcomes included patient reports of: pain severity as measured
by a VAS for pain compared with VAS for comfort; whether
the surgical wound was bothersome or unpleasant; the
level of bother as measured by a 0– 10-point scale, where
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‘0’ is no bother and ‘10’ is the most bothersome; whether
the patient required additional analgesia; whether the
patient preferred to be asked about their comfort level or
pain level; and whether the patient considered the postoperative wound to be injury and disability or healing and recovery. Ongoing follow-up and postoperative management
of all patients took place as per usual practice.
Study power
We used the mean and standard deviation estimates from
pilot data of inverted VAS for comfort or VAS for pain assessments in 18 postoperative women. We calculated that to
show a clinically relevant difference of 20 mm between
pain and comfort groups, sample sizes of 137 and 114 participants/group were required, at rest and with movement, respectively, to give the study a power of 80% with an a ¼0.05.
We assumed equivalence for our primary outcome VNRS as
shown in several previous studies11 and planned to recruit
150 women/group to accommodate for unforeseen losses
of data or participant withdrawals from the study.
Additional outcome data regarding urgency of Caesarean
section, intraoperative blood loss, Apgar scores, and, admissions to the neonatal unit were collected from our hospital’s
clinical information service. All outcome data were transcribed onto a computerized spreadsheet (ExcelTM ) and analysed according to the intention to treat (ITT) principle.
Comfort scale data were flipped so as to assess the degree
of discomfort with the standard measures of VNRS and VAS
for pain. Dichotomous outcomes were reported as relative
risk (RR) with 95% confidence intervals (95% CI). Nonparametric VNRS data and patient characteristic data were
analysed using the Kruskal– Wallis test.
Results
Figure 2 shows the participant trial flow. Three hundred and
thirty-seven women were assessed for eligibility. Of these
women, 37 were excluded as they were non-English speaking
and required an interpreter. The remaining 300 women were
randomized and included in the analyses. No women withdrew from the study after randomization and there were
no losses to follow-up.
There were no clinically significant differences between the
two groups with regard to patient characteristics and perioperative anaesthesia and analgesia management (Table 2).
Table 3 shows VNRS and VAS scores at rest and movement
in women according to group allocation. Patient perceptions
of the postoperative wound and bother scores are also shown.
In Group P, 84 of the 111 women (75.7%) who initially
reported that they had pain, also reported later that they
were comfortable when specifically asked. Similarly, in Group
C, 112 (79.4%) of the 141 women who stated that they were
comfortable also reported pain when specifically asked.
However, only 18 women in Group C reporting pain (15.1%)
stated that they were bothered by it. In contrast in Group P,
61 (55%) of the 111 women, who reported they had pain,
were bothered by it. Seven women in Group P (4.7%) and
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Pain vs comfort scores after Caesarean section
A
Least
pain
Most
pain
0 mm
100 mm
B
Least
comfortable
Most
comfortable
0 mm
100 mm
Fig 1 VAS for comfort and for pain. (A) Pain VAS: diagram shows both front and back sides of the sliding scale. The diamond shape slides along
the scale, used to indicate patient’s pain level. (B) Comfort VAS (diagram shows both front and back sides of the sliding scale). The diamond
shape slides along the scale, used to indicate patient’s comfort level.
Assessed for eligibility
(n = 337)
Excluded (n =37)
Not meeting inclusion criteria
due to non-English speaking
Randomized (n =300)
Allocated to Group P (n =150)
Received allocated questionnaire
(n = 150)
Allocated to group C (n = 150)
Received allocated questionnaire
(n =150)
Analysed
n =150
Analysed
n =150
Fig 2 Participant flow diagram.
four women in Group C (2.7%) who reported that they were
comfortable requested additional analgesia.
Women allocated to Group P were more likely to prefer
being asked about their pain than those in the comfort
group (RR 1.28, 1.03, 1.60, P¼0.026). In Group P, 75 women
(50%) preferred to be asked pain scores and 38 women
(25.3%) preferred to be asked for comfort scores. This difference was not seen in Group C, 58 women (38.6%) vs 54
(36.0%). Of the 300 women recruited, 127 women were undecided, had no preference, or provided no reason for their
preference to be asked for their pain scores or comfort
scores. Some patients commented that they preferred to
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Chooi et al.
Table 2 Baseline patient characteristic data of Groups P and C. CS, Caesarean section; n, number; BMI, body mass index; IQR, inter-quartile
range; CSE, combined spinal –epidural
Characteristic
Age [mean (range)]
Group P (n5150)
31.2 (18-42)
Group C (n5150)
30.8 (20-43)
P-value
0.629
Primiparity [n (%)]
69 (46)
73 (49)
0.644
Previous CS [n (%)]
63 (42)
57 (38)
0.480
BMI [median (IQR)]
26 (23, 31)
26 (23, 30)
0.744
Epidural [n (%)]
51 (34)
41 (27)
0.211
Spinal [n (%)]
91 (60)
98 (65)
0.403
8 (5)
6 (4)
0.584
0 (0)
5 (3)
0.024
67 (45)
60 (40)
0.413
Route of intraoperative anaesthesia
Regional anaesthesia
CSE [n (%)]
General anaesthesia [n (%)]
Elective CS [n (%]
Grade of emergency Caesarean section
Immediate
6 (4)
5 (3)
0.759
Within 30 min
7 (4)
11(7)
0.331
Within 1 h
19 (13)
25 (17)
0.327
Within 4 h
8 (5)
13 (9)
0.258
Within 24 h
34 (23)
27 (18)
Not stated
9 (6)
9 (6)
0.315
1
Blood loss during Caesarean section
,500 ml
59 (39)
70 (47)
0.200
500– 1000 ml
76 (51)
65 (43)
0.203
≥1000 ml
15 (10)
15 (10)
Apgar scores [median (IQR, range)]
9 (9-9, 6-10)
9 (9-9, 4-10)
1
0.584
Number of neonates admitted to
Level 2 neonatal care
32 (21)
44 (29)
0.111
Level 3 neonatal care
15 (10)
19 (13)
0.466
0.562
Postoperative analgesia
None [n (%)]
1 (1)
2 (1)
Simple/non-opioid [n (%)]
56 (37)
56 (37)
1
Opioid [n (%)]
93 (62)
92 (61)
0.905
Antiemetics
Nil
15 (10)
17 (11)
0.708
Single agent
16 (11)
15 (10)
0.850
Dual agent
110 (73)
104 (69)
0.444
Triple agent
9 (6)
14 (9)
0.278
Last analgesia before interview
Nil since operation [n (%)]
2 (1)
2 (1)
Simple/non-opioid [n (%)]
91 (61)
90 (60)
Opioid [n (%)]
57 (38)
58 (39)
Last analgesia to interview time [mean (SD)] (min)
Time since anaesthetic [median (IQR)] (min)
1
0.906
0.905
160 (75, 240)
177.5 (82.5, 252.5)
0.331
1412.5 (985, 1600)
1310 (1075, 1570)
0.340
Patient activity
In bed [n (%)]
104 (69)
85 (57)
0.023
In chair [n (%)]
17 (11)
32 (21)
0.019
Ambulating [n (%)]
29 (19)
33 (22)
0.568
None [n (%)]
25 (17)
44 (29)
0.009
Baby [n (%)]
36 (24)
33 (22)
0.681
Other [n (%)]
38 (25)
31 (21)
0.337
Baby and other [n (%)]
51 (34)
42 (28)
0.261
Other people in room
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Pain vs comfort scores after Caesarean section
Table 3 VNRS and VAS at rest and movement in women according to group allocation are presented. Patient perceptions of the postoperative
wound and ‘bother scores’ are also shown. VNRS, verbal numerical rating score; VAS, visual analogue scale; n, number; IQR, inter-quartile range;
RR, relative risk; CI, confidence interval; IS, Inverted scores; AS, Actual scores
Question
Group P (n5150)
Group C (n5150)
RR (95% CI)
P-value
Do you have pain? yes [n (%)]
111 (74)
119 (79)
0.275
Are you comfortable? yes [n (%)]
118 (79)
141 (94)
,0.001
Rest
VNRS [median (IQR)]
VAS [median (IQR)]
2 (1, 4)
23 (10, 40)
IS: 2 (0.5, 3)
AS: 8 (7, 9.5)
0.001
IS: 12.5 (2, 29)
AS: 87.5 (71, 98)
,0.001
IS: 4 (3, 5)
AS: 6 (5, 7)
,0.001
IS: 46 (30, 59)
AS: 54 (41, 70)
,0.001
Movement
VNRS [median (IQR)]
VAS [median (IQR)]
Are you bothered? yes [n (%)]
VNRS Bother score [median (IQR)]
Reported sensations as ‘unpleasant’ [n (%)]
6 (4, 7)
58 (40, 72)
61 (40)
4 (2, 6)
18 (12)
3.39 (2.11, 5.45)
1 (0, 3)
,0.001
,0.001
104 (69.3)
31 (20.7)
3.05 (2.20, 4.23)
,0.001
Reported sensation as ‘tissue damage’ [n (%)]
44 (29.3)
22 (14.7)
2.0 (1.30, 3.18)
,0.001
Reported sensations as ‘healing and recovery’ [n (%)]
81 (54)
105 (70)
0.77 (0.64, 0.92)
,0.01
More analgesia needed? yes [n (%)]
26 (17)
6 (4)
4.33 (1.84, 10.22)
,0.001
be asked their pain scores rather than comfort scores
because it was easier to rate and they were more familiar
with the scale. Women preferring the comfort scale commented that ‘comfort was more important than pain’ or
‘the word pain reminds me of my pain’.
Discussion
We have presented a randomized trial assessing the postsurgical evaluation of patient experiences by asking about pain
compared with asking about comfort. It is the only clinical
study to assess the effects of assessing pain on postoperative
experiences and patient perceptions, using a priori outcomes.
This report responds in part to the call for more research into
the placebo and nocebo effects of communication16 and
follows on from the landmark research by Lang and colleagues1 showing that negative suggestions can increase perioperative pain and anxiety. Although this issue has not
previously been considered of clinical relevance in the
context of assessing pain, there is clear evidence to the
contrary in other settings.1 2 7 17 18 A previous study
has demonstrated that in the assessment of pain after
Caesarean section, women are more likely to report pain
when asked ‘Do you have pain?’ compared with when
women are asked ‘Are you comfortable?’ It may be that if
patients are asked if they are in pain after operation a ‘yes’
is more likely, than if questioned ‘How are you?’ or ‘Are you
comfortable?’15 As the use of the ‘pain’ word in a phrase
may lead to the communication functioning as a negative
suggestion, we avoided asking about pain and comfort in
the same patient by randomizing for comfort and pain yet
still asking about different aspects of the postoperative experience in a standardized way.
The key findings of our study show that when comparing
VNRS for pain and comfort, lower scores are found for the
inverted comfort score than their equivalent pain score.
This finding also was shown with the use of VAS at rest and
with movement. When women were asked specifically, ‘Do
you have pain?’, an approximately equal number of women
reported pain in the two groups. This suggests that women
will report pain when directly asked, irrespective of whether
it bothers them or needs treating. When women were
asked, ‘Are you comfortable?’, significantly more women in
Group C reported that they were comfortable compared
with those allocated to Group P. Interestingly, the negative
suggestions used in Group P seem to have resulted in an
increased number of patients reporting that their postoperative sensations were unpleasant, more bothersome,
and perceived as tissue damage and injury rather than
healing and recovery (Table 3). Patients allocated to Group
P also had more requests for additional analgesia than
those participants allocated to Group C. These results are
consistent with previous studies suggesting that the use of
negative words increase patient pain and anxiety levels.1 2
Surprisingly, more than half of the women in Group P who
reported that they had pain also stated that they were comfortable when asked directly, and the majority of these
patients neither desired nor required additional analgesia.
As suggested previously, our findings clearly demonstrate
that asking about pain and pain scores alone do not give
healthcare providers enough clinically useful information to
decide if patients are receiving adequate postoperative
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analgesia or require an intervention.17 19 Indeed, enquiring
about whether patients are actually bothered by pain, and
whether they desire any treatment for it, may be more
useful questions to ask when considering whether an intervention for postoperative pain is indicated. Consistent with
previous research in other settings, our avoidance of negative
suggestions when using comfort scores rather than standard
pain scores has not shown any observable harms. This suggests that the use of comfort scores may have an advantage
over traditional postoperative assessments using pain scores.
Our findings appear to be consistent with recent research on
pain processing regarding modulation of the anterior cingulate cortex when negative suggestions are used and how
this affects pain processing and influences patients’ clinical
experience.7 8 Although more women allocated to Group P
preferred to be asked about their pain scores rather than
their comfort scores, many were unsure of their reasons.
Some women did report ‘familiarity’ and ‘ease of use’ as
reasons for their preference.
There were a number of limitations to this study. First,
there are no exact antonyms to pain and it could be
argued that the word ‘comfort’ may not be a suitable
antonym for ‘pain’. In other contexts, one might question
whether our primary outcome to assess pain severity with
the degree of comfort is a primary outcome at all rather
than a description of two separate assessment methods.
However, in the context of assessing postoperative pain
and in the laboratory, it appears likely that as soon as pain
is mentioned, it is likely to focus the patient on pain and associate the perception of sensations in a negative way.17 18
Our statistical comparison between the ‘pain’ and ‘comfort’
groups relied upon an inversion of comfort scores such that
the anchors are reversed, that is, ‘most pain’ becomes translated to ‘least comfortable’ and ‘least pain’ gets translated to
‘most comfortable’. The inverse transformation used in this
study appears to have more than just face validity for the
anchors, as they were asked in a way that focused the
patient on the sensations associated with the Caesarean
wound. Although uncommon, similar inverted scales have
been used previously in the context of a 0– 10 ‘pain relief’
scale, where ‘0’ was no pain relief and ‘10’ was maximum
pain relief.11 19 However, it is difficult to be certain whether
a particular pain score say, 3 of 10 pain really corresponds
to a 7 of 10 for comfort. This would be an interesting area
for future research. The style and expression of the assessors
could have potentially impacted on our study findings.
However, the highly structured nature of the words used in
intervention and control groups, the limited number of investigators asking the questions, and the excellent internal validity in terms of randomization and allocation concealment
should have minimized any risk of bias in this regard.
Women were questioned at a separate time to the usual
ward rounds by obstetric and anaesthetic teams and our
study does not address how patients were questioned by
doctors and nurses about their pain before the assessment
in this study. However, when assessing pain, clinical differences in approach would be expected to have been equally
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Chooi et al.
distributed across groups by the randomization process.
The researchers conducted interviews in a standardized
and structured manner but were not blinded to participant
group allocation. In addition, there were no expectations of
showing a difference between pain and comfort scores by
assessors which should have minimized any potential for
bias. Blinding of assessors should be a consideration in
future studies investigating the effects on pain when it is
measured.
This study may be considered to have ethical challenges
as our study protocol had ethics committee approval for
written informed consent to be obtained after the postoperative assessment. As with other research investigating
subconscious patient responses to communication, patient
consent before the intervention was thought likely to influence our outcomes of interest.2 The need for additional
pain relief was not tracked over time because of the limited
resources available. However, we were able to confirm that
all women requesting postoperative analgesia did receive
it. Study participants may have responded to the researcher
that they did not want additional analgesia, but then sometime later may have asked for analgesia. Neonatal outcomes
and maternal complications from Caesarean section could
have potentially influenced pain perception, but this was
found to be comparable between groups (Table 2). Further
details in this regard would be an interesting consideration
for future research. The self-funded nature of this study did
not allow for multiple visits or prolonged follow-up which
would be an interesting aspect for future research in assessing whether the use of negative language in the assessment of pain influences the length of stay in hospital,
nausea and vomiting, or even the incidence of chronic
pain. It would also be interesting to investigate whether
these results are applicable to women who are potentially
experiencing postoperative pain in other settings such as
after general surgery. Further investigation involving male
patients and those in private and non-tertiary hospitals
would also be of interest. Further research into patient preferences may facilitate further our understanding of the
power of words when interacting with patients.
Traditionally, it has been suggested that regular assessment and measures of pain makes pain visible and thus
improves management, particularly in acute pain.12 Our
trial findings suggest that questioning patients about their
pain and pain scores after Caesarean section adversely
affects patient reports of their postoperative experiences,
possibly by focusing the patient on their pain and therefore
exacerbating the unpleasantness and bothersome nature
of the postoperative wound. This suggests that the belief
that repeated use of pain scores making pain visible may
also be explained as an effect of repeated negative suggestions increasing its incidence, its exacerbation, or both. Similarly, the view that recording pain intensity as ‘the fifth vital
sign’ can improve acute pain management20 21 is based on
relatively poor evidence (Level III-3).11 Our study findings
suggest that not only is the response to pain questioning dependent on how postoperative questions are phrased but
Pain vs comfort scores after Caesarean section
that current testing may be adversely affecting patients’
postoperative experiences. The evidence from the current
and previous studies suggests a naive simplicity to expect
that one could reliably guide appropriate pain management
by reducing something as complex as the experience of pain
to a single number.22
It would seem reasonable to conduct post-anaesthesia
interviews using a more permissive open question structure
initially such as ‘How are you feeling’ rather than ‘How
much pain have you got?’ Avoidance of the use of the
‘pain’ or similar negative words until they are expressed by
the patient may be a consideration in its assessment and
management. If future research confirms our findings, the
continued encouragement of using pain scores in the
context of postoperative pain as the fifth vital sign21 should
be questioned, and possibly replaced with more neutral or
positive language. As with pain relief ratings,19 inverted
comfort scores are likely to be related to, but distinct from,
changes in pain intensity. Although they read somewhat
lower than pain scores, inverted comfort scores may be
one possible way of avoiding the effects of negative suggestions when assessing postoperative pain after Caesarean
section.
Acknowledgements
We thank Ann Fitzgerald for assistance with supplementary
data retrieval and acknowledge the support and assistance
of nurses, midwives, and patient participants at the
Women’s and Children’s Hospital in Adelaide.
Declaration of interest
None declared.
Funding
This study received no external funding.
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