Pain, 15 (1983) 283-293 Elsevier Biomedical Press

283

Preoperative Predictors of Postoperative Pain

Linda E. Scott, George A. Clum and Judith B. Peoples

Virginia Polytechnic Instlrute and State University, Blacksburg, Va. (U.S.A.)

(Received 7 January 198 I, accepted 23 June 1982)

Summary

This study attempted to predict postoperative pain from preoperative level of anxiety and the amount of information patients possessed regarding their surgery.

Pain was assessed via the McGill Pain Questionnaire (MPQ) and a measure of pain complaints - number of analgesics taken. High levels of state anxiety and a high degree of information predicted the Present Pain Intensity measured of the MPQ,

but did not predict the Pain Rating Index portion of the MPQ. The number of

analgesics taken was predicted from the amount of information but not the level of presurgical anxiety. Biographical variables were unrelated to postoperative pain, The

results were discussed in terms of State-Trait Anxiety theory, Janis’ curvilinear prediction model and a contextual perspective of information imparting.

Introduction

There is a growing body of literature which has examined the relationship between psychological states and personality variables and the magnitude of per- ceived pain. Examining this relationship, in a prediction framework, is especially important with respect to clinical pain. Sternbach 1191 notes that experimentally

induced pain research may yield quite different information than research in clinical pain, where a patient’s anxiety, level of discomfort, and concern for well-being is considerably greater. Surgery provides an ideal setting for examining the relationship

between individual variables and pain. Surgery is a high stress situation which evokes intense emotional reactions, involves considerable physical danger, and is quite painful. Additionally, the management of pain is a primary concern during the recovery process, and the identification of predictor variables ean provide valuable insight for the design of intervention programs to reduce the level of discomfort.

Previous research has identified several psychological factors which affect experi-

0304-3959/83/0000-0000/$03.00 Q 1983 Elsevier Science Publishers

enced discomfort after surgery: ( 1) level and t\~pc of anxiety; (2) amount and type 01

information about the procedure: and (3) cultural and experimental factors which mediate pain expression. The patient’s anxiety level. in aIlticipati(~n of the impend-

ing medical procedure, has been shown to significantly affect perception of pain intensity. Drew et al. [4] found that analgesic usage was much higher among patients

undergoing photocoagulation for retinal repair than in patients undergoing major abdonlinal surgery. The primary difference being that. even though ph~~t~~c(~agLlia-

tion is known to be relatively painless, it is associated with high levels of anxiety. Martinez-Urrutia [ 121 observed that high anxious surgery patients reported more

pain than low anxious patients. in both the pre- and postoperative periods. At least two researchers, Janis [7] and Spielberger et al. [ l&17]. have attempted to posit

differential reactions to surgery from the level and type of anxiety the individual

experiences prior to surgery. Janis [7] contends that a curvilinear relationship exists

between fear (similar to the current term ‘state anxiety’) and postoperative recovery. Janis reported that surgery patients, who experienced a moderate level of fear. would recover in the shortest period of time. with the fewest c~~mpiicati~)ns, whereas

patients with either high or low anxiety would have the poorest recoveries. Spielberger et al. 116,171 delineated two types of anxiety, a transitory emotional

state that varies in intensity and fluctuates over time (A state) and a personality disposition that remains relatively stable over time (A trait). Spielberger et at. [ 171

report that trait anxiety. purp~~rtedly a stable measure of interpersonal threat. should not be predictive of pefceived pain. State anxiety, however, which increases in response to physically threatening situations, should be predictive of pain.

The amount of information an individual has about a procedure has been found

to be both helpful [S,9] and harmful [ I,1 I] with respect to pain levels and complica-

tions during postoperative recovery. This conflicting evidence is apparently due to

the use of different types of information. the context in which it is presented. and

individual variability in response to preparatory information. For instance. Egbert et al. [5] presented patients with an intensive program that included hehaviorat and cognitive means of dealing with the pain and atress as wet1 as infornlation regarding

possible reactions and experiences during recovery. This program resulted in signifi- cant reductions in postoperative pain medication over that of controls. Johnson [9]

found that a detailed description of the specific sensory characteristics of the pain to be experienced. prior to the induction of ischemie pain. significantly reduced the

amount of distress reported by subjects. Conversely, Langer et al. [II] found preparatory information to he totally ineffective as a means of reducing pain and

recovery time. However, preparatory information. in this instance. consisted only of general information about procedures, possible complications and locations of pain.

Langer et al. proposed that the il~formation may have served to sensitize the patients to the discomforting aspects of the impending surgery. Further support for this notion is provided by Kanfer and Goldfoot [lo] who have demonstrated that the presentation of a negative set, prior to a measure of pain tolerance. using the cold-pressor test, significantty increases discomfort ratings and reduces pain toler- ance. The negative set condition consisted of specific information about the expected intensity, location. and nature (i.e., cramping) of the pain. It also appears that the

285

relationship between information and response to stress is mediated by individual

coping styles. Andrew [ 11, in an examination of the interaction between preparatory

information and three levels of coping style, found information to be helpful to non-specific defenders (individuals with coping styles that involve both denial and

sensitization), but detrimental to individuals who displayed denial as their character- istic defense. The nature of the relationship between information and pain expres-

sion is unclear, and information cannot be presumed to have an ‘inoculatory’ effect

as Janis [8] has suggested. Finally, previous studies have reported that cultural and demographic, experien-

tal, and situational factors also mediate perceived pain. Woodrow et al. [21], for instance, reported that women, Negroes and Orientals, and older persons are more sensitive to pain, that is, have a lower pain threshold. Sternbach [20] reports that

cultural background and ethnic membership can affect pain tolerance, as well as physiological responses to experimentally induced pain. Mersky and Spear [ 141 have

also reported that frequency of pain complaints, in a clinical setting, is related to

socioeconomic status, the number of previous pain experiences or exposures to

family members with similar experiences, family size, and marital adjustment.

Chapman and Cox [3] also report that the subjective response to surgery is affected

by the type of surgery and the meaning attached to it. In a study that compared

renal transplant donors and recipients and general surgery patients, they found differential patterns of pain between general surgery patients and kidney patients.

The purpose of the present study is to (1) examine the relationship of postopera- tive pain to state and trait anxiety; (2) determine the reIationship between a patient’s level of information and pain expression through self-report and requests for analgesics; and (3) examine these variables in a prediction framework to assess the

relationship of preoperative states to postoperative pain. It was hypothesized that state anxiety is a significant predictor of postoperative pain and that the relationship is linear. It was also hypothesized that information is predictive of postoperative pain, serving to sensitize the patients to the upcoming discomfort.

Method

Subjects A total of 48 patients, admitted for elective cholecystectomy *, participated in the

study. There were 9 males and 39 females, and the ages ranged from 21 to 73 years

with a mean age of 45. None of the patients had a medical history of organic brain damage, mental retardations or other significant psycholo~cal disturbances. Patients were referred in the order that they were scheduled for surgery and were approached

if they were physically well enough to complete the measures.

* Cholecystectomy - surgical removal of the gallbladder.

Thr McGill Ptrin Que~trontwire (MPQ). The MPQ is a self-report measure of pain

utilizing adjectives which describe the sensory, affective. and evaluative components of pain. The Pain Rating Index (PRI) portion of the MPQ consists of 20 subscales divided into three major classes of word descriptors [ 131. A separate portion of the

MPQ. Present Pain Intensity (PPI), is rated on a 5-point scale from ‘mild’ to ‘excruciating,’ according to the amount of pain that is felt at the time of the testing.

Sltrtc-Twit Anxiety lncentot:~~ (STAI). The STAI is comprised of tu.0 self-report scales to measure state anxiety (A state) and trait anxiety (A trait). each consisting ol

20 statements that are used to describe a person’s feelings or disposition [ 161.

Few o/‘Surget~~~ Quesfion (FSQ). The FSQ was devised by Martinez-Urrutia [12] for the purpose of measuring individual differences in fear about the upcoming

surgery. The FSQ is worded as follows: ‘In general, how much fear or concern do

you have about surgical operations?’ Subjects are requested to respond hi rating

themselves on a 6-point scale, from ‘no fear’ to ‘extreme fear.’

Surgetyy lnjormurion Questtotmuirr (S/Q). The SIQ consists of four questions related to the subject’s information regarding complications, post-surgical pain, preparatory procedures. and reasons for needing gallbladder surgery. This question- naire was developed specifically for this study to reflect the amount of information that each patient had concerning hospital procedures and the nature of the discom- fort that he/she was about to undergo. Possible answers to each question were listed and one point was scored for each item accurately reported by the patient. Possible scores ranged from 0 to 14. Interrater reliability for this scale was high (r = 0.96).

Atzu/ge.sic:r receiced (ANAL.<;). This was tabulated from the drug administration record in each patient’s file. Pain medications were available upon request during the postoperative period and each administration was recorded by the nurse in the

patient’s chart. The number of administrations of a pain medication. when based on

requests by the patient, was considered a behavioral index of the magnitude of pain

experienced by the patient. However, analgesics were not equated for dose and type

in thins study.

Procedure

Each day on which elective surgeries were scheduled. each of the two hospitals participating in the study were contacted and a list of persons posted for surgery the following day was obtained. Each patient was approached and asked to participate in the study, then asked to read and sign a consent form. The project was presented as a study of patients’ reactions to surgical operations. Each patient was tested twice, first on the afternoon preceding surgery and then 5 days after surgery. counting the day after surgery as the first postoperative day. The preoperative session consisted of a semi-structured interview which was taped. The questions from the Surgery Information Questionnaire were included in this interview and preserved on tape to be rated at a later date. Following the taped interview, the patient was given the State-Trait Anxiety Inventory, the McGill Pain Questionnaire, and the Fear of

Surgery Question, in that order.

In the postoperative session the McGill Pain Questionnaire, the A state portion of

287

the State-Trait Anxiety Scale, and the Fear of Surgery Question were again adminis-

tered. After the patients had been discharged and their medical records were available, each file was examined and the number of analgesics received during the

entire postoperative period was tabulated. Demographic data (age, sex, race, marital status, religion, occupation, and educational level) were also obtained from the

patient’s records and from the text of the taped interview.

Results

~e~ogra~~~c, situational, and prior experience effects In order to evaluate the effect of a number of nominal variables, such as

education, occupation, sex, hospital, and surgeon, dummy coding was utilized. Each level of the nominal variables was recoded as a vector in which the level of interest

equalled 1 and all the other levels were equal to zero. There was no relationship

between education, occupation, sex, surgeon and any of the pain measures. Also, age was negatively correlated (r = - 0.31, P < 0.01) with preoperative state anxiety, but was unrelated to any of the pain or other anxiety measures. Although only 9 patients were obtained from one hospital, t test analysis revealed a significant difference in number of analgesics requested (means = 20.67, 14.36; t = 1.97, P c 0.05). However,

when hospital was entered as a predictor in the step-wise multiple regression, it did not contribute a significant portion of the variance and could not be considered an

important predictor. There were only 9 males in the patient sample, but sex differences did appear in t

test analyses. Trait anxiety was significantly lower for males (mean = 31.67) than for

females (mean = 38.54; t = 2.14, P -c 0.05). There was also a significant difference in postoperative state anxiety, between males (mean = 28.89) and females (mean =

35.79; t = 2.13, P < 0.05). Prior experience with surgery, tabulated as the actual number of previous major

operations, was significantly correlated with amount of information (r = 0.55, P < 0.001) and postsurgical PPI (r = 0.45, P < 0.001). Number of previous surgeries was not related to the other pain measures, PRI and analgesics requested, either pre- or postoperatively. Stepwise multiple regression analyses, in which number of previous

surgeries was entered with the other preoperative prediction variables, showed previous surgeries to be a significant predictor of postoperative PPI (see Table I).

To more closely examine the effect of previous experience with surgery and

possible prediction models for postoperative pain, the sample was divided into two groups, patients who had had one or more (N = 37) and those who had never had surgeries (N = 11). It was not possible to produce significant predictors, even if they

exist, in stepwise regression on the no-surgery group, due to the very low sample size,

However, in the previous surgery group, SIQ was entered as a significant predictor

of analgesics (R = 0.29, F = 3.17, P -c 0.05); preoperative state anxiety (R = 0.36, F= 5.10, P < 0.05) and SIQ (R = 0.47, F = 4.23, P < 0.01) were entered as predic- tors of PPI2.

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Anxiety Pearson Product-Moment correlation showed that trait anxiety is related to both

preoperative measures from the McGill Pain Questionnaire, PPIi (r = 0.37, P < 0.01) and PRIl (r = 0.34, P < 0.05) (see Table II). Trait anxiety, however, was not correlated with any of the three postoperative pain measures. State anxiety for the

preoperative period, STATEl, was correlated with PRIl (r = 0.29, P < 0.05) and PPIl (r = 0.26, P < 0.05) as well. However STATE1 was also correlated with one of

the postoperative pain measures, PP12 (R = 0.30, P < 0.05). This relationship is also

reflected in multiple regression analysis, in which STATE1 proved to be the second most important preoperative predictor of postoperative pain, as measured by PP12

(R = 0.47, F = 4.57, P < 0.05) (see Table I). STATE1 did not prove to be a signifi-

cant predictor of either analgesics requested or PR12. In the postoperative period,

state anxiety, STATE2, was correlated with the number of analgesics requested

(r = 0.33, P < 0.01) and PR12 (r = 0.37, P < 0.01). FSQl did not prove to be a significant predictor of any of the pain measures. FSQ2 was significantly correlated

with postoperative PPI and PRI.

As was expected, state anxiety decreased significantly from the preoperative to

the postoperative period. The mean for STATE1 was 41.17 and 34.50 for STATE2

(t = 3.46, P < 0.001). The possibility of a non-linear relationship between anxiety and pain was also

examined. Preoperative measures of trait and state anxiety were squared and entered

in a hierarchical multiple regression to determine if the curvilinear component contributed a significant amount of variance above that of the linear component.

Neither trait nor state anxiety was curvilinearly related to any of the pain measures.

Information Pearson Product-Moment correlation revealed that there was a significant positive

correlation between levels of information, as measured by the SIQ, and two of the three measures of postoperative pain response, number of analgesics requested (r = 0.33, P < 0.01) and PPI2 (r = 0.38, P < 0.01) {see Table II). Number of previous surgeries was also significantly correlated with SIQ (r = 0.56, P -c 0.001). In stepwise

multiple regression analysis, information was entered consistently as the first and most important predictor of the criterion measures PP12 (R = 0.38, F = 7.67, P c 0.001) and number of analgesics requested (R = 0.33, F = 5.45, P < 0.05). PR12 was not related to the amount of information patients possessed prior to surgery.

R~~ationsh~~s among the pain measures Correlations between the PRI (sensory, affective, evaluative, and miscellaneous

scales combined), the PPI, and number of analgesics were computed (see Table II). PRI was correlated with PPI in both the preoperative (r = 0.60, P < 0.001) and

postoperative period (r = 0.53, P < 0.001). Number of analgesics taken was unre- lated to the PRI either pre- or postoperatively but was correlated with the postsurgi- cal measure of PPI (r = 0.29, P < 0.05).

The preoperative measure of PRI was correlated with the postoperative measure of PRI (r = 0.29, P -C 0.05). Also, presurgical PRI was entered as the only significant

TIVF. AND POST0PtIRATIVtI PERIODS _- _... .__.__-. . __ .~~~~ ~_~.. ______ .__.

sly I’RI I ,’ 1’1’1 ! -.- .-~~~~.~_~-_~~~_~~ __._~~~_..__ .._______~ __

SIQ I .oo PRI 1 0.02

PPI I 0.04 (i.hO ***

FSQ 1 -- 0.003 O.Ih 0.17

STATE 1 0.05 0.29 * 0.26 *

ANALG 0.33 * 0. I 2 -- 0.18

PRI:! 0.10 0.29 * 0.0s

PP12 0.38 ** ii.16 0.17

FSQ2 0. I6 0.16 U.24 *

TRAIT -0.11 0.34 * 0.37 *

STATE.2 0.07 0.06 -- 0.10 -.-- ..I- .--... -_l.-

* P ( 0.05; **pi 0.01; ***pi 0.001.

“ One (I) refers to the preoperative measure of a variable.

0.50 ***

0.03 -- 0.06 0. IS 11.i’) 0.24 * 0.30 *

0.66 *** 0.66 ***

0.34 ** 0.65 ***

0.19 I). I5 --~---_ .-... ._--.

predictor (see Table I) of postsurgical PRI, in a multjple regression analysis,

Preoperative PPI was not related to postoperative PPI.

Discussion

Results from t-he present study must be considered tentative because of the small number of subjects and the utilization of subjects undergoing only gallbladder surgery.

State anxiety was demonstrated to be a significant, linear predictor of postopera- tive pain. Previous studies [2,4,12] had demonstrated that anxiety was an ii~portant factor in the experience of pain, but none had examined the influence of preopera-

tive anxiety levels on postoperative pain. This is especially interesting since state anxiety was elevated prior to surgery but declined after surgery. Trait anxiety was not predictive of any of the pain measures. This is consistent with the State-Trait Anxiety theory [ 171 which predicts a differential response to threat for high and low

trait anxious individuals only in situations concerning personal adequacy. No support was found for Janis’ [7] contention that a curvilinear relationship

exists between state anxiety and postoperative recovery. One reason for this may include the fact that Janis’ subjects were psychiatric patients who scored in the higher ranges of anxiety than subjects in the present sample. Also. Janis’ [7] description of the ‘work or worry,’ which, at moderate levels, was found to have an emotional inoculatory effect, may not be adequateIy represented by the measures of

preoperative fear or state anxiety.

291

ANALG PRI2 h PP12 FSQ2 TRAIT STATE2

0.11

0.29 * 0.53 ***

0.12 0.30 * 0.48 ***

- 0.08 0.02 0.17 0.43 ***

0.33 ** 0.31 ** 0.19 0.30 * 0.08 1 .oo

h Two (2) refers to the postoperative measure of a variable.

Information Information about the impending surgery was predictive of higher levels of pain.

As Langer et al. [ 1 l] and Kanfer and Goldfoot [lo] have suggested, information

about impending discomforts may sensitize the individual to the experience. Never- theless, this finding is at odds with those studies which report information imparting

to improve post-surgical adjustment. Those studies which report information giving to be related to the reduction of pain had also included some means of creating a positive set for the patient, either through reassurances [9,18] or intensive programs with specific instructions on dealing with the pain [5]. It may be that information about surgery should be presented along with additional information regarding how to cope with the situation. An alternative explanation of these results is that

information is a function of previous surgeries and that the latter sensitizes patients to postoperative pain. Since information was a significant negative predictor of

postoperative pain in patients who had previous surgery, and such patients could be expected to have the same opportunity to acquire information, the latter explanation

appears unlikely. Future studies will have to assess the circumstances surrounding when information has a salutary effect and when it does not.

Pain tolerance, pain expression, and pain measurement

Previous studies [ 14,201 have reported that pain tolerance, the maximum amount of pain a person will tolerate, and pain expression (or readiness to complain of pain and seek relief in a clinical setting) are related to personality, situational, cultural, and experiential factors. In the present study, pain was measured by the two indices from the MPQ and a tabulation of the number of analgesics received post-surgically. Melzack [13] contends that the PRI is an indicator of the sensory component of

pain. whereas the PPi 1s reported to fluctuate as a function of the psyclmlcygical

factors of the moment. such as anxiety and mood. The results of this study appear to

support this distinction. PRI. the sensory component, was not predicted by, pxycho- logical factors. such as anxiety, information, or number of prev:iou.\ ~urgeriea. PPI

Was related to these cognitive and affective variablea, as Melzack [ 131 has suggested.

The tabulation of analgesics received postoperatively constitutes a measure of the

readiness to ~ompIain of pain, or pain behavior, as Fordyce et al. 161 term it. That is,

a person is identifying himself as in pain by seeking a means of relieving pain. Although the overall relationship between information and analgesics was relatively

small. it may be inferred that prior experience, and/or a tendency for information seeking, affects pain behavior as measured h\j the number of analgesics taken. This has some logical basis in that individuals who are better informed about their

surgery could be expected to exert greater control over their environment by

requesting medication.

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