An exploration of the relationship between anxiety, expectations and memory for postoperative pain

Acute Pain (2007) 9, 135—143

An exploration of the relationship between anxiety, expectations and memory for postoperative pain Rohini Terry a,∗, Catherine Niven a, Eric Brodie b, Ray Jones c, Morag Prowse c,1 a

NMAHP Research Unit, University of Stirling, United Kingdom Department of Psychology, Glasgow Caledonian University, United Kingdom c Faculty of Health and Social Work, University of Plymouth, United Kingdom b

Received 21 September 2006 ; received in revised form 1 April 2007; accepted 24 April 2007 Available online 11 June 2007 KEYWORDS Pain memory; Expectations; Anxiety; Pain intensity; Pain quality

Summary Background: It is unclear how expectations of postoperative pain, anxiety and memory for that pain are interrelated. This study aimed to (1) explore the relationship between patients’ expectations, actual pain experiences and retrospective reports of postoperative pain intensity and quality and (2) examine the relationships between pain ratings and measures of patient anxiety. Methods: Twenty-four participants used the short form McGill Pain Questionnaire (SFMPQ) and VASs to report expectations of pain prior to surgery, actual postoperative pain and retrospective ratings 4—6 weeks postoperatively. Anxiety was measured using Spielberger’s state trait anxiety inventory prior to surgery, within 48 h following surgery and 4—6 weeks postoperatively. Results: No significant differences were found between intensity ratings of expectations, actual experiences and retrospective ratings of pain. However, kappa analyses revealed inconsistencies in the choice of SF-MPQ descriptors used to express pain quality. Anxiety scores were positively related to pain intensity ratings and negatively related to the consistency between qualitative pain reports. Conclusion: Whilst memory for pain intensity appeared to be more accurate than for pain quality, the study also highlighted difficulties in inferring recollective experiences from verbal reports. The study also confirms the importance of reducing patients’ anxiety and avoiding unrealistic expectations of postoperative pain. © 2007 Elsevier B.V. All rights reserved.

∗ Corresponding author at: Department of Psychology, University of Stirling,United Kingdom. Tel.: +44 1786 466340x6287; fax: +44 1786 466344. E-mail address: [email protected] (R. Terry). 1 Present address: Faculty of Health, Life and Social Sciences, Napier University, Edinburgh, United Kingdom.

1366-0071/$ — see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.acpain.2007.04.041

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1. Introduction Surgery is often physically and psychologically stressful and in the postoperative period, many patients experience significant amounts of pain or discomfort. By and large, health professionals try to ensure patients receive as much information about the forthcoming surgery as possible and to ensure that patients’ expectations of resultant pain or discomfort are realistic. Although the provision of such preoperative information has often been found to have a positive effect on pain, anxiety and outcomes such as length of hospital stay and patient satisfaction [1], subsequent expectations of pain may give rise to anticipatory anxiety or even cause patients to delay or avoid seeking treatment. Further, the extent to which patients’ expectations (formed prior to surgery, based upon the specific patient information provided and other prior knowledge) affects both their experience of postoperative pain and recollections of that pain, has received little empirical attention. It is important to investigate how accurate these pain memories are as it is the memory of pain which may influence future health related decisions. Redelmeier et al. [2] for example, found that memories of the intensity of pain experienced during the last moments of a medical screening procedure significantly influenced the uptake rates of further medical screening. Clinicians also frequently rely upon patients’ recollections of pain in determining the therapeutic efficacy of a particular treatment [3]. Previous research has found that patients are generally accurate in their predictions of postoperative pain intensity made prior to surgery [4,5], although both overestimations and underestimations of the intensity of the expected pain have been observed [6—11]. The extent to which the qualities of postoperative pain can be accurately anticipated before it has actually been experienced has not been systematically examined. Similarly, retrospective reports of pain intensity have often been regarded as fairly reliable, with reasonable correlations existing between ratings of pain intensity whilst actually experiencing it and those provided at a later time when pain free [3,12,13]. On the other hand, memory for the quality of a pain experience (that is, its specific sensory and affective components) has been found to be more variable [14—19]. Earlier studies suggested that memory for pain quality is good [14,15]. But a number of studies which have assessed memory for the qualitative aspects of pain using the non-parametric Cohen’s kappa statistic

R. Terry et al. [16—19], to provide a more stringent assessment of agreement between qualitative pain descriptors selected from the McGill Pain Questionnaire [20] to report actual and recalled pain, have suggested that memory for the qualitative nature of pain may not be recalled as accurately as pain intensity. Many associated factors, however, are likely to affect the accuracy of retrospective pain reports. Prior research has suggested that memory for pain may be influenced by an individual’s general (semantic) knowledge about a pain, as well as by their personal experience of that pain [17,18]. Expectations of a pain which has not previously been experienced may draw on this semantic knowledge and may confound pain memory, especially when anxiety levels are high. Thus, expectations of the forthcoming pain, which may be influenced by levels of anxiety, may distort the way pain is anticipated, perceived and remembered [21—24]. Kent [22], for example, found that where anxiety levels were high, retrospective reports of dental pain intensity were more closely associated with patients’ expectations of the pain than with their reports made whilst actually experiencing dental pain. The relationship between pain recall accuracy and anxiety could be further investigated by examining data for associations between anxiety and kappa values, which can provide a reflection of the consistency between actual and retrospective pain ratings. In addition, the extent to which the relationship between expectations of pain and recollections of pain is mediated by anxiety may be further explored by investigating associations between anxiety ratings and the kappa values which reflect the level of consistency between expectations of pain and retrospective reports. The first aim of the present study, then, was to explore the inter-relationships between patients’ expectations of pain, actual pain experienced in the first two postoperative days and their retrospective reports of postoperative pain (4—6 weeks after surgery). It was hypothesised that expectations of pain, ratings of actual pain and retrospective ratings of pain would be positively correlated. This hypothesis was based on the previous research finding that individuals are able to provide appropriate estimates of pain that they have not personally experienced [17,18] and that retrospective reports of pain intensity have generally been found to be accurate [13—16]. The second aim was to examine the relationships between measures of pain and measures of patient anxiety. It was hypothesised that measures of anxiety would be negatively associated with

Exploration of the relationship between anxiety, expectations and memory pain rating consistency, measured using Cohen’s kappa.

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experience and included the descriptors ‘aching’ and ‘tiring’.

2.4. Measures

2. Materials and methods 2.1. Design This prospective study was carried out in a large hospital in the south of England during the summer of 2003. Reports of pain intensity and quality and measures of anxiety were obtained on three occasions from patients undergoing uncomplicated long or short saphenous vein (LSV or SSV) day surgery: (1) preoperatively, after patients had been admitted to hospital for surgery, but prior to the administration of any preoperative medication; (2) postoperatively in the 48 h following surgery, when actual pain experiences and state anxiety were assessed, and (3) retrospectively, 4—6 weeks following surgery, when patients’ recall ratings of postoperative pain were obtained along with ratings of state and trait anxiety. While many kinds of acute postoperative pain could be examined in a study of this kind, postoperative pain following LSV/SSV surgery (commonly known as varicose vein surgery) was chosen as a suitable model of pain for several reasons. First, this type of surgery is relatively straightforward and usually takes place in a day care setting. Further, many other routine day surgery procedures are exploratory and likely to cause anxiety not directly related to the surgery itself. In addition, the surgery is not gender-specific.

The short form McGill Pain Questionnaire (SF-MPQ) [25] and visual analogue pain intensity scales (VAS) were used to assess expectations, actual pain within 48 h of surgery and retrospective ratings of pain 4—6 weeks later. The SF-MPQ is made up of 15 descriptors taken from the standard long form MPQ; 11 sensory descriptors and 4 affective descriptors which can be endorsed as being mild, moderate or severe. The SF-MPQ yields a description of the pain, a count of the number of words chosen (NWC) to describe the pain as well as a total pain severity score; the pain rating index (PRI), which can be subdivided into sensory and affective components. The VAS intensity scale consisted of a 10 cm horizontal line anchored at each end by the descriptions ‘no pain’ on the left and ‘pain as bad as possible’ on the right. The participant’s task was to mark on the line the position which reflected the intensity of the pain. Spielberger’s state trait anxiety inventory (STAI) [26] was used to assess both state and trait anxiety. The STAI is a widely used measure of anxiety, where participants endorse statements to reflect their current level of anxiety (state anxiety) and their general level of anxiety (trait anxiety). Participants completed both sections of the STAI preoperatively (pre-op anxiety) and 4—6 weeks after surgery (anxiety 4—6 weeks) while the STAI-state section only was completed in the postoperative period (post-op anxiety).

2.2. Participants

2.5. Procedure

Over a period of 15 weeks, all patients scheduled for straightforward LSV or SSV surgery in a single NHS hospital trust were invited to take part in the research.

Local (North and East Devon) Research Ethical Committee approval was obtained. Letters were sent to 64 patients between 1 and 8 weeks prior to their date for surgery to explain that the study was taking place, along with a patient information sheet outlining the nature of the study. Participants were approached by the researcher (RT) for the first time at the day surgery unit, after they had been admitted by nursing staff. Those who wished to participate signed a consent form, before rating their expectations of any postoperative pain using the SF-MPQ and the VAS and completing both the state and trait anxiety sections of the STAI. Participants were then given the postoperative questionnaire to complete once they had been discharged from hospital, which included the SF-MPQ, a VAS to report pain intensity and the state section of the STAI. They were asked to complete this questionnaire

2.3. Materials All patients received an information leaflet from their consultant (vascular surgeon) which provided a detailed explanation of what could be expected when having varicose vein surgery. This leaflet provided a description of the likely nature of the postoperative pain under the heading ‘How much will it hurt?’ and suggested that ‘most people will experience discomfort only’ and noting that ‘it is common for the area under the groin to feel tender for a few days’. The information leaflet also referred to other aspects of the postoperative

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at home, within the first 48 postoperative hours, before taking a dose of analgesic medication, and then to return it by post to the researcher. Participants who completed this questionnaire were then sent a final questionnaire by post, 4 weeks after surgery. A covering letter instructed them to try to recall the pain experienced at the time they had completed the postoperative questionnaire, again using the SF-MPQ and VAS, and to provide a further rating of state and trait anxiety using the STAI.

2.6. Statistical analyses Statistical analyses were carried out using SPSS (formerly known as the Statistical Package for the Social Sciences) Version 13.0. Pain ratings obtained from the SF-MPQ and VAS were compared using ANOVAS. Correlation analysis was also carried out to investigate the relationships between pain and anxiety ratings. Because a high number of correlation coefficients were reported in this study, a conservative type 1 error rate (0.01) was adopted, in order to reduce the possibility of significant findings being observed through chance alone. Cohen’s kappa (Ä) was used to provide a measure of the consistency of SF-MPQ descriptor reselection between the three questionnaires. Kappa incorporates a correction for ‘chance’ agreement (the re-selection of the SF-MPQ descriptors) between two occasions of testing. Kappa yields a value between 0, reflecting agreement between ratings no better than chance, and 1, which reflects perfect agreement. Following Fleiss [27], kappa values were categorized as follows: excellent, Ä =0.75—1; good, Ä = 0.6—0.75; fair, Ä = 0.4—0.6; poor, Ä ≤ 0.4.

3. Results Thirty-eight patients were approached at the day surgery units. Of these, 9 men and 25 women agreed to take part. A total of 7 men and 17 women provided complete data on the questionnaires at each

of the three assessment times. The mean age of the participants whose data were used in the analyses was 46 years (range 26—72, median 43 years).

3.1. Pain intensity—–expectations, actual and retrospective ratings Mean SF-MPQ PRI ratings to describe expectations of pain of 9.5 (S.D. 5.5) and retrospective PRI ratings of 9.1 (S.D. 6.5) were slightly higher than actual pain ratings of 8.0 (S.D. 5.1). This pattern of results was observed for the other two measures of pain, the number of words chosen (NWC) from the SF-MPQ and the VAS, as detailed in Table 1. However, repeated measures ANOVAs revealed no significant differences across the three times of assessment for any of the pain intensity measures (PRI total scores: F(2,46) = 1.49, p > 0.05, sensory scores: F(2,46) = 1.96, p > 0.05, affective/evaluative scores: F(2,46) = 0.12, p > 0.05, NWC: F(2,46) = 0.23, p > 0.05 and VAS: F(2,46) = 1.46, p > 0.05).

3.2. Pain profiles Similar patterns of verbal descriptors were selected from the SF-MPQ to express expectations of pain, actual pain and retrospective reports, and are graphically illustrated in Fig. 1. As in previous research [16] a ‘Pain Profile’ was constructed to illustrate the pattern of SF-MPQ descriptors selected at each of the assessment times.

3.3. Comparison of SF-MPQ descriptor use Kappa was used to investigate the agreement between each participants’ choice of SF-MPQ descriptors selected at each assessment time, that is, between (i) expectations of pain and actual pain, (ii) actual pain and retrospective ratings, and (iii) expectations of pain and retrospective ratings. Kappa was calculated to provide (1) an estimate of the consistency with which participants selected the same SF-MPQ descriptors (e.g., throbbing, shooting, etc.) across rating times, regardless

Table 1 Mean SF-MPQ PRI, NWC and VAS ratings (S.D.) to report expectations of pain, actual pain ratings and retrospective ratings (4—6 weeks following surgery)

Total SF-MPQ PRI (S.D.) Sensory score (S.D.) Affective/evaluative score (S.D.) NWC 100 mm VAS

Expectations of pain

Actual pain ratings

Retrospective ratings

9.5 8.4 1.2 5.9 33.8

8.0 6.8 1.2 5.6 28.1

9.1 8.1 1.0 5.9 30.1

(5.5) (4.3) (1.4) (3.0) (17.5)

(5.1) (4.5) (1.6) (3.1) (16.2)

(6.5) (6.2) (1.5) (3.6) (17.3)

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Fig. 1 Pain profiles showing number of participants selecting each of the SF-MPQ descriptors to express expectations of pain, actual pain and retrospective ratings. Table 2 Mean kappa values (S.D.) reflecting agreement between pain ratings for SF-MPQ descriptors only and for SF-MPQ descriptors endorsed as mild, moderate or severe

SF-MPQ descriptors only SF-MPQ descriptors and intensity (mild, moderate or severe)

Expectations/actual

Actual/retrospective

Expectations/retrospective

0.42 (0.28) 0.24 (0.27)

0.53 (0.23) 0.34 (0.35)

0.49 (0.29) 0.26 (0.26)

of the intensity rating assigned and (2) an estimate of the consistency with which participants selected an SF-MPQ descriptor at a particular level of intensity (mild, moderate or severe) at each rating time. The kappa values are shown in Table 2, comparing expectations of pain with actual pain ratings, actual pain ratings with retrospective reports and expectations of pain with retrospective reports. The kappa values ranged from 0.42 to 0.53 for descriptor selection consistency and 0.24—0.34 for descriptors plus intensity selection consistency (that is, ‘fair’ or ‘poor’, if Fleiss’ categorisation of kappa is used).

3.4. Ratings of state and trait anxiety and pain Table 3 shows the anxiety scores on the state and trait sections of the STAI before surgery, in the 48 h after surgery and 4—6 weeks postoperatively when retrospective ratings of pain were made. Table 4 details the correlations between anxiety and pain ratings. Pre- and post-operative state anxiety and VAS ratings in the postoperative period were significantly positively correlated (p < 0.01). Trait anxiety was stable across assessment times and positively correlated with actual VAS pain ratings. No significant correlations were observed between state or trait anxiety and retrospective VAS ratings

of pain. Anxiety levels were not significantly correlated to PRI ratings of postoperative pain. Almost all measures of state and trait anxiety were negatively correlated with kappa values (Tables 5 and 6). Preoperative state anxiety was significantly negatively correlated to the kappa values reflecting agreement between the SF-MPQ descriptors used to report expectations of pain and actual pain; SF-MPQ descriptors chosen to describe expectations of pain were more likely to match those chosen to report actual pain if anxiety was lower (Table 5). This was the only significant association observed between anxiety and kappa values reflecting the consistency of SF-MPQ descriptor selection. No significant associations between anxiety rat-

Table 3 Preoperative state and trait anxiety ratings, state anxiety <48 h postoperatively and state and trait anxiety 5—6 weeks postoperatively Preoperative State Trait

41.0 (14.7) 34.3 (9.9)

<48 h postoperative State

29.4 (8.9)

Retrospective questionnaire State Trait

28.0 (8.3) 33.1 (10.2)

The values are mean anxiety rating (S.D.).

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Table 4

Correlations between anxiety and pain ratings (SF-MPQ PRI and VAS)

Anxiety

Preoperative

<48 h postoperative

4—6 weeks post-op

State

Trait

State

State

Trait

VAS expectations VAS actual VAS retrospective

0.30 0.52* 0.25

0.32 0.55* 0.16

— 0.58* 0.17

— — 0.13

— — 0.32

PRI expectations PRI actual PRI retrospective

0.23 0.25 0.13

0.42 0.43 0.25

— 0.35 0.28

— — 0.19

— — 0.34

*

Correlation significant at the 0.01 level (two-tailed).

Table 5

Correlations between anxiety ratings and kappa values (descriptors only)

Kappa comparisons MPQ descriptors only

Actual/retrospective Expectations/actual Expectations/retrospective *

Anxiety Preoperative

<48 h postoperative

Anxiety 4—6 weeks

State

Trait

State

State

Trait

— −0.53* −0.36

— −0.37 −0.32

−0.29 −0.43 —

−0.04 — −0.42

−0.36 — −0.29

Correlation is significant at the 0.01 level (two-tailed).

Table 6

Correlations between anxiety and kappa values (descriptors plus intensity)

Kappa comparisons MPQ descriptors and intensity

Actual/retrospective Expect/actual Expectations/retrospective

Anxiety Preoperative

<48 h postoperative

Anxiety 4—6 weeks

State

Trait

State

State

Trait

— −0.01 0.19

— −0.20 −0.02

−0.01 −0.16 0.06

−0.02 — −0.14

0.08 — −0.12

ings and kappa values reflecting the consistency of descriptor and intensity selection were found, with r values ranging from −0.20 to 0.19.

4. Discussion 4.1. Pain expectations, actual experiences and retrospective reports The participants in this study expected slightly more pain than they subsequently experienced. Although the difference between rating times was not significant, we recognise that this study is of a preliminary, exploratory nature and as such, is relatively lower powered; greater participant numbers may have led to the discrepancies of this size being statistically significantly different. However, in terms of clinical relevance, we would argue that the participants’ expectations of postoperative

pain were reasonably accurate, with discrepancies in the SF-MPQ PRI scores of only 1.5 between assessment times, on a scale which ranges from 0 to 45, and a difference of 5.6 mm on a 100 mm VAS intensity rating scale. Pakula and Milvidaite◦ [28] found a 10% error rate when requiring participants to mark a VAS at two predetermined positions. This variation was then used in their study to set the estimate of inherent unreliability in pain ratings at 10%. Further research is underway to investigate the extent to which expectations of pain were influenced by the comprehensive patient information leaflet provided, and whether such estimates could be made without this kind of preparatory information. The intensity of the participants’ actual postoperative pain experienced in the first 48 postoperative hours was relatively low, with a mean SF-MPQ PRI rating of 8.0 out of a possible rating of 45, and a mean VAS rating of 28.1 mm

Exploration of the relationship between anxiety, expectations and memory on a 100 mm linear scale. Melzack and Katz [29] reported a comparison of SF-MPQ PRI ratings for acute and chronic pain conditions ranging from around 7 to 29. The PRI ratings obtained in the present study are likely to reflect the relatively minor nature of the surgery, in comparison to the types of surgery reported in other studies which have concluded that ‘severe pain continues to the third postoperative day and beyond’ [30, p. 61] and investigations which have reported SF-MPQ PRI ratings of around 15 to describe postoperative pain following various surgical procedures including breast augmentation, coronary artery bypass graft surgery, cholecystectomy and laminectomy [25,31]. Retrospective ratings of pain were, like expectations, not significantly different to actual pain ratings, which can provide support for our first hypothesis, that expectations of pain, actual pain and retrospective ratings of pain intensity would be significantly correlated. Previous research has often interpreted such findings to indicate that memory for pain intensity is reliable [3], although again, due to the relatively small sample size in the present study, further research needs to be carried out to confirm these data. The patterns of SF-MPQ descriptors selected to qualitatively express pain at each rating time were similar to one another (as shown in the pain profile in Fig. 1). The quality of the pain was most commonly described as being throbbing, tender, aching, heavy and tiring—–descriptors which predominately express the sensory qualities of the pain experience rather than its affect. Prior research has also found that patients tended to select affective descriptors less frequently than sensory ones in postoperative situations [32,33]. Zalon [33] pointed out that in the postoperative period, patients may attempt to prevent their pain from impacting upon their mood, which might help to explain the less frequent selection of affective pain descriptors in the present study. SF-MPQ descriptors most frequently chosen by the patients in the present study also reflect those provided in the patient information leaflet, which included the descriptors ‘aching’ ‘tender’ and ‘tiring’. This suggests that patients based their expectations of postoperative pain on the information that had been provided for them, and that this information was appropriate and accurate, matching both their actual postoperative pain experiences and their recollections of the pain. However, the extent to which each participant was consistent in their verbal descriptions of pain quality cannot be gauged from the pain profiles alone. To augment these data, kappa was

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used to provide a measure of agreement between the three pain rating times. These analyses indicate that the agreement between the SF-MPQ descriptors selected at each rating time at a particular level of intensity was ‘poor’, or at best, ‘fair’ when the level of SF-MPQ descriptor intensity was disregarded in the kappa analyses. These kappa values are comparable to those obtained in prior research employing the full MPQ [16—19] and, taken together, suggest that regardless of the type of pain under investigation or version of the MPQ employed, the kappa values reflecting agreement across pain rating times remain quite low. Given these findings, it is reasonable to speculate that the ability to recall the qualitative aspects of a prior pain experience may be limited [16—19]. Earlier research [17] has also suggested that a reductive process occurs when individuals describe the qualitative nature of a prior pain, whereby only its defining qualities are recalled. It is possible, then, that the qualitative dimensions of pain might be recalled at a broader, ‘type of pain’ level; whether or not, for example, the pain simply included thermal, incisive, or temporal sensations. However, it is also possible to argue that pain memory cannot be gauged adequately simply by comparing the verbal descriptors selected at each pain assessment time. It is possible that patients may simply be using appropriate descriptors to report the pain without any recollection of it, in the same way they were able to make appropriate estimates of postoperative pain prior to surgery. Thus, apparently ‘correct’ pain recollections (which have been inferred when actual and retrospective pain ratings match) should not necessarily be assumed to reflect episodic memory of a prior pain event. Cognitive researchers have long recognised the problems in inferring recollective experience from such overt responses, since the seminal work of Tulving [34] more than two decades ago, which distinguished between two types of recollective experience — ‘remembering’ — the episodic, conscious recollection of events from one’s personal past, and ‘knowing’, recollections void of detailed sensorial and contextual (spatio-temporal) information relating to the prior experience. However, the finding that SF-MPQ descriptors are different to those used whilst in pain does not discount the influence of episodic memory in pain recollections. When making retrospective reports of a prior pain event, individuals may recall the types of sensations previously experienced and use analogous descriptors which nonetheless express their clear, conscious recollections of their postoperative pain.

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4.2. Anxiety, expectations and memory for pain As would be expected, state anxiety was notably higher when assessed shortly before surgery (41.0) than at each of the postoperative assessment times (<30.0). The low trait anxiety ratings may have contributed to the generally low usage of the affective/evaluative components of the SF-MPQ. The positive correlations between expectations of pain intensity (VAS ratings) and anxiety ratings and between actual pain intensity and anxiety ratings demonstrate that participants with higher levels of anxiety tended to expect and report experiencing greater levels of pain (Table 4). This finding is in agreement with previous research which has demonstrated that increased levels of anxiety are associated with reports of increased pain intensity [24,35—37]. Although the associations were positive, there were no significant correlations between PRI ratings and anxiety, perhaps due to the fact that the SF-MPQ measures dimensions of pain other than pain severity, which may not be influenced by levels of anxiety. A positive association has not always been found when the relationship between pain and anxiety has been investigated [35—37], and it was hypothesised that higher anxiety ratings would be associated with less consistent pain ratings—–that is, lower kappa values. But the data obtained in the present study provided no evidence for this hypothesis. However, the kappa analyses do provide an indication that expectations of pain were less likely to agree with actual pain ratings if anxiety was higher. This association suggests that more anxious patients tended to have less realistic expectations of the forthcoming pain, although these expectations do not significantly influence pain recall accuracy.

4.3. Limitations The discussion of our findings is limited by the exploratory nature of the research and the relatively small number of patients participating in the study. We acknowledge that more significant discrepancies between pain rating times might have been observed in a larger study. However, our data provide information regarding pain quality and intensity — as well as patients’ expectations of postoperative pain and anxiety levels — in a clinical setting which has not previously been considered in the memory for pain literature, and our sample size is comparable to those reported in the majority of other investigations which have assessed memory for pain intensity and quality in other settings [14—19].

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5. Conclusion In agreement with previous research findings, and in line with the first hypothesis, our findings suggest that although patients’ retrospective reports of pain intensity are fairly consistent with those made whilst experiencing postoperative pain, patients’ reports of the qualitative dimensions of pain should be viewed with some caution. However, we suggest that our data also call into question the extent to which retrospective reports of pain can be considered to reflect ‘memory’ for that pain and indicate the need to employ a more direct method of investigating the phenomenological experience of recalling acute pain. The comprehensive information provided to patients participating in this study appeared to be beneficial in that it allowed them to develop appropriate and realistic expectations of the impending postoperative pain. The data from the present study indicate that anxiety appears to be positively associated to expectations of pain and ratings of actual pain intensity, although anxiety was not found to influence the accuracy of retrospective pain reports. The finding that higher levels of anxiety were associated with expectations of greater amounts of postoperative pain, and with reports of more severe pain following surgery, highlights the importance of reducing patient anxiety in clinical settings wherever possible.

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