Pain, 55 (1993) 339-346 0 1993 Elsevier Science Publishers B.V. All rights resetved 0304-3959/93/$06.00

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PAIN 02396

Pain behavior predictors among fibromyalgia patients

Karen E. Baumstark a,*, Susan P. Buckelew a, Kenneth J. Sher b, Niels Beck ‘, Keith L. Buescher d, John Hewett d and Timothy M. Crews a*b

a Division of Clinical Health Psychology and Neuropsychology, Department of Physical Medicine and Rehabilitation, 501 Rusk Rehabilitation Center,

and Departments of b Psychology, and ’ Psychiatry, and d Missouri Arthritis Rehabilitation Research Center, University of Missouri, Columbia,

MO 65212 (USA)

(Received 1 September 1992, revision received and accepted 19 May 1993)

Summary This study was designed to assess the reliability and validity of a Pain Behavior Observation method with fibromyalgia syndrome (FS) subjects and to determine the factors which predict pain behavior among FS subjects. Fifty-eight female FS subjects participated in the videotaped Pain Behavior Observation method. Subjects also completed the McGill Pain Questionnaire (MPQ), the Arthritis Impact Measurement Scale (AIMS), and the Symptoms Checklist-90-Revised (SCL-90-R). Pain behavior totals were derived using the Pain Behavior Observation method of McDaniel et al. (1986). Results indicated that the scoring method of Keefe and Block (1982) developed for use with back pain patients was more generalizable to this FS sample. Total pain behavior score using the Keefe and Block scoring method was correlated with self-report pain. Interrater reliability ranged from 0.9 to 0.99. Hierarchical multiple regression analyses revealed that age and physical disability predicted the total pain behaviors. The Pain Behavior Observation method appears a valid pain measurement technique independent of depression among FS patients. Directions for future research are discussed.

Key words: Fibromyalgia syndrome; Pain Behavior Observation method; McGill Pain Questionaire; Arthritis Impact Measurement Scale; Symptoms Checklist-90-Revised; Depression; Psychological factors

Introduction

There are approximately from 3 to 6 million Ameri- cans who suffer from fibromyalgia syndrome (FS), a non-articular rheumatic condition (Wysenbeek et al. 1985). Primary symptoms of FS include the presence of generalized aches, pains, and stiffness, and the pres- ence of characteristic tender points (Wolfe et al. 1984a). Fibromyalgia syndrome is defined by the lack of objec- tive symptoms and the presence of pain. Therefore, the assessment of pain among FS patients is critical.

At least two studies have examined the report of pain symptoms among FS patients (Leavitt and Katz 1989; Uveges et al. 1990). FS patients and rheumatoid arthritis (RA) patients reported bilateral pain of simi-

* Corresponding author: K.E. Baumstark, Division of Clinical Health Psychology and Neuropsychology, Dept. of Physical Medicine and Rehabilitation, 501 Rusk Rehabilitation Center, University of Missouri, Columbia, MO 65212, USA.

lar intensity affecting multiple body sites; however, the pattern of responses for the 2 patient groups was different (Leavitt and Katz 1989). The FS patients reported more diffuse pain (less localized to the joints) over a larger portion of the body, and used a larger number of pain descriptors (including radiating, steady, etc.). Relative to patients with intra-inflammatory arthritides (predominantly rheumatoid arthritis), FS patients reported greater pain intensity involving more body regions, and used more affective and sensory descriptions of the pain. ‘General diffuse aching’ does not convey the complexity of the pain experience of FS patients (Uveges et al. 1990).

Because of the subjective experience of pain and the multidimensional nature of pain in fibromyalgia, pain assessment is problematic. Behavioral techniques for pain assessment have been developed to provide a quantitative and observable assessment of the pain experience (Fordyce 1976; Fordyce et al. 1984). Keefe and Block (1982) developed a behavioral observation technique to assess pain behavior among low back pain

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patients which was subsequently modified for use with RA and osteoarthritis (OA) patients. Among RA pa- tients, pain behavior ratings were positively and signifi- cantly correlated with self-report pain measures and functional disability measures (McDaniel et al. 1986). In addition, a number of pain behaviors were signifi- cantly and positively correlated with disease activity measures of RA, and with Rheumatology Fellows rat- ings of pain intensity and severity (Anderson et al. 1987a). Using multiple regression procedures, a modi- fied rheumatoid activity index and/ or disease duration were significant predictors of pain behavior among RA patients.

The role of psychological factors in predicting pain behavior is controversial. McDaniel et al. (1986) found low correlations between pain behavior scores and self-reported depression in RA patients. The only pain behavior which was significantly correlated with de- pression was guarding (r = 0.31, P < 0.05). Similarly, Anderson et al. (1987b) found that certain affective disorders, including dysthymic disorder, major depres- sion, and bipolar disorder-depressed, did not inde- pendently contribute over and above the medical in- dices in predicting pain behaviors among RA patients. In contrast, Buescher et al. (19911 found that observed pain behavior among RA patients is related to self-ef- ficacy after controlling for disease activity. Among back pain patients, Keefe et al. (1986) found that depression was correlated with pain behavior. Although the pain behavior methodology has been described as a pain assessment tool independent of depression (Anderson et al. 1987b), this finding has not generalized to other patient populations (Keefe et al. 1986).

The lack of objective physical findings associated with fibromyalgia has led to speculation that psycholog- ical factors may be important in fibromyalgia. For example, depression, anxiety, and reactivity to stress have often been included among the symptoms, modu- lating factors, and/or etiological agents of FS (Yunus 1984). Studies using psychological assessment instru- ments have demonstrated that FS subjects report more psychological distress than RA patients (Payne et al. 1982; Ahles et al. 1984, 1987; Wolfe et al. 1984b; Scudds et al. 1987) and healthy controls (Ahles et al. 1984; Scudds et al. 1987). In contrast, Clark et al. (1985) found no significant differences on the Symp- toms Checklist-90-Revised (SCL-90-R), the Beck De- pression Inventory (BDI), and the Spielberger State- Trait Anxiety Inventory (STAI), between FS patients and a control sample of general medical patients. This FS sample was obtained by screening patients in a general medical clinic who were not seeking care for their fibromyalgia symptoms; therefore, it may be more representative of the general community of FS pa- tients, many of whom may not seek health care.

In addition to pain, patients with FS report signifi-

cant disability. For example, FS subjects report more physical disability relative to a community control sam- ple (Cathey et al. 1986) and a control group of RA patients (Russell et al. 1989; Hawley and Wolfe 1991). While self-report pain and disability are correlated (Millard 1989; Tait et al. 19901, the relationship be- tween pain behavior and disability has not been estab- lished in the FS population.

To date, the Pain Behavior Observation method has not been used with FS patients. In addition, the rela- tionships between pain behavior, disability, and depres- sion have not been explored. This study was designed to: (1) assess the reliability and validity of the Pain Behavior Observation method of McDaniel et al. (1986) with FS patients by examining inter-rater reliability, the internal consistency of the pain behavior measure, and the correlation between observed pain behavior and self-reported pain; and (2) to assess the role that physical ability and depression play in predicting pain behavior among FS patients. It was hypothesized that the physical activities score from the Arthritis Impact Measurement Scale (AIMS, a measure of physical dis- ability) would predict total number of pain behaviors when the effects of total number of painful body areas and age were controlled. It was also hypothesized that the depression T score from the SCL-90-R would not predict the total number of pain behaviors, when the effects of number of painful body areas and age were controlled.

Methods

Subjects Fifty-eight female subjects who met the revised criteria of Yunus

et al. (1987) for primary FS participated in this study. All subjects

had the following signs and symptoms: (a) generalized aches. pain, or

stiffness involving at least 4 anatomical regions for a minimum of 3

months, (b) an absence of secondary causes, and (c) a minimum of

2-4 tender points. Only 2 tender points were required if subjects met

at least 3 of the minor criteria, including pain in at least 7 sites,

hurting all over, disturbed sleep, fatigue, general anxiety or tension,

and irritable bowel syndrome. Subjects were excluded from the study

on the basis of the following factors: (a) age below 20 or above 68, (b)

presence of a psychotic disorder, (c) presence of other uncontrolled

medical disorders, such as cancer, (d) presence of a major communi-

cation disorder, and (e) illiteracy. Average age was 44.3 (SD. = 9.3)

years; average education level was 12.7 (S.D. = 3) years.

Procedure Consecutive potential subjects identified as meeting study criteria

were recruited from a university-based Rheumatology and Physical

Medicine and Rehabilitation (PM&R) Clinic, as well as through a

private rheumatology practice. Subjects were contacted by telephone

or in the PM&R Clinic, and the assessment procedure was de-

scribed. Informed consent was obtained prior to conducting the

assessment. Subjects completed 3 self-report measures: the SCL-90-R

(Derogatis 19771, the McGill Pain Questionnaire (MPQ) (Melzack

19751, and the AIMS (Meenan et al. 1980). Each subject was video-

taped for a IO-min interval while performing a standardized and

random sequence of sitting, walking, standing, and reclining. Subjects

were told that the video recording sewed as a record of body

movement. During the recording session, the examiner did not

converse with the subjects other than to provide instructions on how

to perform the maneuvers.

The subject’s video recordings were viewed and scored by two

independent trained raters. One of these raters had participated in

formal training in the Pain Behavior Observation method at the

Bowman Gray School of Medicine. Eight behaviors (guarding, brac-

ing, grimacing, sighing, rigidity, passive rubbing, active rubbing, and

rigidity) have been identified and defined by McDaniel et al. (1986)

as applicable to rheumatic pain. To score the video recordings, the

lo-min sessions were divided into twenty 30-set intervals. Each

interval consisted of a 20-set observation phase during which the

rater observed the occurrence of specific behaviors, and a lo-set

recording phase in which the rater noted on a score sheet the

specific behaviors observed.

Measures Symptom Checklist-90-Revised. The SCL-90-R assesses the pres-

ence and degree of psychological distress. Subjects rate 90 symptoms

on a scale from 0 = not at all to 4 = extremely. There are 9 clinical

scales (Somatization, Obsessive-Compulsive, Interpersonal Sensitiv-

ity, Depression, Anxiety, Hostility, Phobic Anxiety, Paranoid Ideation,

and Psychoticism) reflecting a variety of psychopathologies, and 3

global distress measures (Global Severity Index (GSI), Positive

Symptom Distress Index (PS.D.11, and Positive Symptom Total

(PST)), reflecting the degree of symptom severity. Test-retest reliabil-

ity coefficients range from 0.78 to 0.90. Internal consistency of the

subscales range from 0.77 to 0.90 (Derogatis 1977).

McGill Pain Questionnaire. This well-validated questionnaire as-

sesses pain on several dimensions including sensory pain, affective

pain, and evaluative pain. Test-retest reliability coefficients of the

MPQ have ranged from 0.70 (Melzack 1975) to 0.73 (Graham et al.

1980). A study assessing recall of past pain experience revealed that

test-retest reliability ranged from 0.72 for the evaluative dimension,

to 0.97 for the present pain rating index (Hunter et al. 1979).

Melzack (1975) has provided evidence for the validity of the MPQ by

showing that each of the subscales reflected changes in pain experi-

ence following treatment to manage or relieve pain. In addition,

factor analytic studies have provided evidence of construct validity

for the three pain dimensions (e.g., Byrne et al. 19821.

Arthritis Impact Measurement Scales. The AIMS, a 45item ques-

tionnaire, provides reliable assessment of such variables as dexterity,

physical activity, social activity, and social roles (Meenan et al. 1980).

Mean test-retest reliabilities for the 9 subscales range from 0.84 to

0.92. Strong evidence for the utility of this measure in clinical

research involving rheumatic disease patients has been provided

(Meenan et al. 1980, 1984). Although developed for use with arthritis

patients, the AIMS also has been used as a functional status measure

TABLE I

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with FS patients (Uveges et al. 1990). The Physical Activities sub-

scale of the AIMS was used as a measure of disability in this study.

The items comprising this scale are consistent with complaints often

described by FS patients in the clinic (see Table Il. In our sample,

responses tended to be uniformly distributed on this subscale (mean

= 4.83, S.D. = 2.70, median = 4.00, range = O-10). It appears to be

an adequate measure of physical disability in this sample.

Behavioral Observation Method of pain assessment. This observa-

tional method was developed by McDaniel et al. (1986) for use with

rheumatic disease patients. Each subject was videotaped for a lo-min

interval while performing a standardized and random sequence of

sitting, walking, standing, and reclining. Each sequence included l-

and 2-min sitting and standing periods, two 1-min reclining periods,

and two 1-min walking periods. The total pain behavior score was

derived from the summation of 8 specific pain behaviors (i.e., guard-

ing, bracing, grimacing, sighing, rigidity, passive rubbing, active rub-

bing, and self-stimulation). Based on the results of our reliability and

validity data (see below), rigidity, passive rubbing, active rubbing, and

self-stimulation were omitted from the predictive data analyses. This

scoring modification was consistent with the work of Keefe, who

previously developed the behavioral observation method for use with

back pain (Keefe and Block 1982) and OA (Keefe et al. 1987)

patients. McDaniel et al. (19861 reported 96-100% agreement be-

tween trained raters for the 8 pain behaviors. Kappa coefficients for

the individual pain behaviors ranged from 0.80 to 1.00 (McDaniel et

al. 1986).

Results

Reliability and validity analyses Table II displays the means, standard deviations,

and range for the occurrence of pain behaviors in our FS sample versus the RA sample of McDaniel et al. (19861, collected from a similar university setting.

Calculations for determining the inter-rater reliabil- ity between the two independent raters of the pain behavior observations were completed using 3 meth- ods. Percent agreement was calculated by adding the number of intervals in which both observers agreed on the occurrence or non-occurrence of a behavior, divid- ing the sum by the total number of intervals, and multiplying by 100. Percentage effective agreement was calculated by dividing the number of intervals in which both observers agreed on the occurrence of a behavior by the number of intervals in which agreements plus

ITEMS COMPRISING THE PHYSICAL ACTIVITY SCALE FROM THE AIMS

Item no. Description

1 Are you unable to walk unless you are assisted by another person or by a cane, crutches, artificial limbs or braces?

2 Do you have any trouble either walking one block or climbing one flight of stairs because of your health?

3 Do you have any trouble either walking several blocks or climbing a few flights of stairs because of your health?

4 Do you have any trouble bending, lifting or stooping because of your health?

5 Does your health limit the kind of vigorous activities you can do such as running, lifting heavy objects or participating

in strenuous sports?

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TABLE II TABLE III

MEAN AND MEASURES OF VARIABILITY OF PAIN BEHAV- IORS SHOWN BY FS vs. RA SAMPLES

RELIABILITY ESTIMATES FOR 8 PAIN BEHAVIORS

Pain behavior Mean + SD. Range

FS (n = 581 :201 (Fns=581 E20!

Guarding 2.31 f 3.15 3.75 ) 3.27 O-13 o- 9 Bracing 0.45 f 1.72 0.50 & 1.47 O-12 0- 6 Grimacing 0.17kO.46 0.00~00.00 0- 2 o- 0 Sighing 0.50+0.84 0.15 kO.49 0- 4 o- 2 Rigidity 0.60+1.34 1.45k3.19 0- 6 o-13 Passive rubbing 9.43+4.13 6.55 k33.72 O-17 O-14 Active rubbing 0.5.5k1.22 1.20t2.50 o- 6 o- 8 Self-stimulation 4.24k4.05 3.70,3.54 O-16 o-12 Pain behavior total 18.26 + 8.65 l-45

Note: RA sample: McDaniel et al., 24 (1986) 165-184.

Pain behavior

Guarding Bracing Grimacing Sighing Rigidity Passive rubbing Active rubbing Self-stimulation

Note: n = 58.

disagreements occurred (McDaniel et al. 1986). Addi- tionally, kappa coefficients were calculated for each pain behavior to obtain a reliability estimate which was unbiased by chance agreements between raters (Lee and Suen 1984). Percentage effective agreement was utilized because several of the pain behaviors were observed infrequently. Kappa coefficients provided es- timates of reliability that were unbiased by chance agreements.

havior measure. For our sample, the total coefficient alpha for the McDaniel method was 0.38, suggesting that the pain behavior measure is not highly internally consistent. Using the modified method, including only guarding, bracing, grimacing, and sighing, the alpha coefficient was higher, yet still low at 0.49, indicating the modification is likely the more internally consistent of the two.

Percentage agreement was approximately 99% for each individual pain behavior. The percentage effective agreement for the pain behaviors was slightly lower but still acceptable, ranging from 82.6% to 100%. Simi- larly, the kappa coefficients were acceptable, ranging from 0.90 to 1.00 (see Table III).

An alpha coefficient analysis was completed to de- termine the degree of internal consistency of both the McDaniel and the modified methods of the pain be-

Spear-man rank-order correlations were completed to explore the relationships among the 8 individual pain behaviors (Table IV). Several pain behaviors were significantly related to each other. Grimacing and guarding (1. = 0.28, P = 0.031, rigidity and guarding (Y = 0.40, P = O.OOZ>, and rigidity and passive rubbing (r = 0.27, P = 0.04) were moderately correlated. Gri- macing and sighing were related (r = 0.38, P = 0.004), as were sighing and self-stimulation (r = 0.33, P = 0.01). No other pain behaviors were related to each other at a significant level. Therefore, the individual pain be- haviors are not independent but appear only moder- ately correlated.

TABLE IV

% Agreement

99.8 1 .oo

99.9 99.9 99.8 99.9 99.5 99.0

% Effective Kappa aggreement coeff.

98.3 0.99 1 .oo 1.00

90.0 0.95 96.6 0.98 93.8 0.97 99.7 0.99 82.6 0.90 96.2 0.97

SPEARMAN RANK-ORDER CORRELATIONS AMONG 8 PAIN BEHAVIORS

Pain behavior Guarding Bracing Grimacing

Guarding Bracing 0.13

(0.34) Grimacing 0.28 -0.00

(0.03) (0.98) Sighing 0.16 0.07 0.38

(0.25) (0.58) (0.003) Rigidity 0.40 - 0.00 0.13

(0.002) (0.98) (0.32) Passive rubbing 0.01 0.00 0.17

(0.93) (0.981 (0.20) Active rubbing -0.16 -0.04 0.21

(0.22) (0.74) (0.11) Self-stimulation 0.13 0.12 0.04

(0.33) (0.37) (0.76)

Note: n = 58. P values appear in parentheses under correlations.

Sighing

0.16 (0.221 0.10

(0.44) 0.17

(0.21) 0.33

(0.01)

Rigidity

0.27 (0.04)

- 0.00 (0.991 0.13

(0.36)

Passive rubbing

0.10 (0.47) 0.17

(0.201

Active rubbing

0.07 (0.62)

TABLE V

SPEARMAN RANK-ORDER CORRELATIONS AMONG PAIN BEHAVIORS AND SELF-REPORTS OF PAIN

Pain behavior Self-reports related to pain

Body VAS

(r) (P) (r) (P)

Guarding 0.07 (0.61) 0.27 (0.04) Bracing 0.07 (0.63) (0.05) (0.72) Grimacing 0.46 (0.0003) 0.25 (0.05) Sighing 0.06 (0.64) - 0.16 (0.24) Rigidity 0.29 (0.03) 0.05 (0.73) Passive rubbing 0.19 (0.16) 0.03 (0.80) Active rubbing 0.07 (0.60) 0.13 (0.34) Self-stimulation 0.10 (0.45) - 0.03 (0.82) Pain behavior total 0.22 (0.09) 0.13 (0.33) Modified pain behavior total 0.13 (0.33) 0.28 (0.03)

Note: n = 58. Body = number of painful body areas from MPQ. VAS = visual analog scale from MPG.

To investigate the concurrent validity of the Pain Behavior Observation assessment method, Spearman rank-order correlations were computed among the pain behaviors and self-reported number of painful body areas and visual analog scale WAS) pain rating (Table V). Pain behavior total (using the method of McDaniel et al. (1986)) was not significantly correlated with the self-report measures of pain, However, guarding was significantly correlated with VAS pain rating (r = 0.27, P = 0.04). Grimacing was significantly correlated with both number of painful body areas (r = 0.46, P = 0.0003) and VAS pain rating (r = 0.25, P = 0.055). Rigidity and number of painful body areas were signifi- cantly correlated (r = 0.29, P = 0.03). Sighing, bracing, passive rubbing, active rubbing, and self-stimulation were not correlated with the self-report pain measures.

These results indicate that the method modifications of McDaniel et al. (1986) did not improve the efficacy of the pain behavior scoring methodology of Keefe and Block (1982) which was originally developed for back

TABLE VI

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pain patients. A modified pain behavior total consis- tent with the method of Keefe and Block including guarding, bracing, grimacing, and sighing was used for the predictive analyses; the newer pain behaviors added or modified by McDaniel et al. (1986) including passive rubbing, active rubbing, self-stimulation, and rigidity, were dropped because they were not correlated with pain intensity measures and did not appear valid for use with FS subjects. Additionally, the pain behavior total was not correlated with pain intensity rating for the McDaniel scoring method (r = 0.13, p = 0.33) but was for the modified pain behavior total based on the scoring methodology of Keefe and Block (r = 0.28, P = 0.03) (see Table V). Therefore, the modified pain behavior total was used for the rest of this study.

Predictive analyses Two hierarchial multiple regression analyses were

conducted to determine the degree to which self-re- ported physical disability or depression predicted the modified pain behavior total, above the contribution of number of painful body areas and age. Predictor vari- ables were entered in 3 steps. The first analysis entered the variables in the following order: (1) number of painful body areas from the MPQ (considered a covari- ate), (2) age, and (3) physical activity score from the AIMS. In the second analysis the first 2 steps were unchanged, and the depression T score from the SCL- 90-R was entered.

In the first analysis, the relationship of physical disability to pain behaviors was examined. Age was a significant predictor of pain behavior over and above painful body areas (P = 0.043). After controlling for the effects of number of painful body areas, both age and the physical activity score from the AIMS were significantly related to the modified pain behavior total (P = 0.04 and P = 0.0008, respectively). As disability increased, total number of pain behaviors increased. The full model accounted for 27% of the variance, with physical disability measured by the physical activities

SUMMARY OF REGRESSION ANALYSES PREDICTING MODIFIED PAIN BEHAVIOR TOTALS

Model Independent Total R* F ratio df P Change For change in R* variable(s) for R* in R2 F ratio df P

Analysis 1 I Body 0.0148 0.841 1,56 0.3630 II I+Age 0.1085 3.348 2,55 0.0425 0.0937 5.78 1, 55 0.02 III II+PA 0.2665 6.541 3,54 0.0008 0.1580 11.63 1, 54 0.001

Analysis 2 I Body 0.0148 0.841 1, 56 0.3630 II I+Age 0.1085 3.348 2, 55 0.0425 0.0937 5.78 1,55 0.02 III II + DEP 0.1404 2.939 3, 54 0.0407 0.0319 2.00 1, 54 0.16

Note: n = 58. Body = number of painful body areas from MPQ. PA = Physical Activity scale from AIMS. DEP = Depression T score from SCL-90-R.

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scale of the AIMS adding an increase of 16% (P= O.OOl), over and above that accounted for by age and number of painful body areas. In the second hierar- chial regression analysis, we examined the relationship of depression (SCL-90-R) to pain behavior. After con- trolling for the effects of age and number of painful body areas, the depression T score from the SCL-90-R was found to be unrelated to the modified pain behav- ior total (see Table VI).

Discussion

The mean number of videotaped pain behaviors in our FS sample and in McDaniel’s RA sample were similar, as were indices of inter-rater reliability. The 3 indices of reliability (percentage agreement, percent- age effective agreement, and kappa coefficients) re- vealed high inter-rater reliability for the pain behav- iors. Nevertheless, both the alpha coefficient analysis as well as the concurrent validity correlations revealed that the Pain Behavior Observation method developed by Keefe and Block (1982) for the assessment of low back pain patients is more generalizable to our FS sample than the version developed for use with a RA sample (McDaniel et al. 1986). In addition the Keefe and Block modified pain behavior total was correlated with self-report pain intensity, while the McDaniel et al. pain behavior total was not. Therefore, the Keefe and Block pain behavior methodology was utilized for the remainder of our study.

This study identified 2 significant predictors of pain behavior: age and physical disability. The older the subject, the more pain behaviors were exhibited. These results are similar to the findings of Keefe et al. (1987) with OA patients. A moderating variable correlating with age might account for the correlation between modified pain behavior total and age. For example, older subjects may be generally less fit, less energetic, more overweight, and more limited in movement (Keefe et al. 1987) perhaps making them more uncomfortable than younger, more fit subjects. Clinical observation throughout the study suggested that many of the sub- jects were overweight to varying degrees, and that the overweight subjects did express more pain behaviorally. Indeed, Keefe et al. (1987) found that in OA patients, obesity was an important predictor of functional im- pairment and pain behavior. We did not collect infor- mation on height and weight in the present study. Future studies in this area of research should measure fitness variables including weight.

After controlling for the effects of number of painful body areas and age, the physical activity score from the AIMS was a significant predictor of the modified pain behavior total. As the physical disability increased, pain behavior scores increased. Patients who perceived

and reported higher levels of physical disability sec- ondary to their fibromyalgia symptoms may have learned to hold painful body areas abnormally to guard against pain. Such behavior may eventually increase pain perception and disability. Furthermore, if such patients feel they are disabled, they may have a higher need to communicate the level of their pain and dis- ability to others. This is particularly important in fi- bromyalgia, a syndrome with few objective signs. Cathey et al. (1986) found that self-assessed disability in FS patients accurately reflects ability to perform stand- ardized work tasks. Hawley et al. (1988) found that functional impairment was an independent explanatory variable for global severity of FS patients’ complaints. These studies and our results suggest that physical ability is often impaired in FS patients, and may have important effects on factors such as behavioral commu- nication of pain, or ratings of global disease severity.

Depression did not predict pain behavior among FS patients. Anderson et al. (1988) similarly found that depression did not predict videotaped pain behavior in a sample of RA patients, after controlling for medical status and demographic variables. Conversely, using low back pain patients and in vivo pain behavior rat- ings, Keefe et al. (1986) found that depression had modest but significant predictive value even after con- trolling for demographic and medical status variables. Recently, Anderson et al. (1989) reported that pain behaviors of RA patients were associated with depres- sion when the ratings occurred during a physical exam- ination and were recorded in vivo without the use of video equipment. Demand characteristics of the video equipment may affect the relationship between depres- sion and pain behaviors and could explain the dis- crepant findings in these studies.

While depression appears unrelated to pain behav- ior in our study and others (e.g., Anderson et al. 1988), it may be that other psychological measures are useful predictors of pain behavior. For example, Buescher et al. (1991) found that while depression scores were unrelated to pain behavior in RA patients, self-efficacy was a predictor of pain behavior. The role of self-ef- ficacy and pain behaviors needs to be explored among FS patients.

Although the Pain Behavior Observation method developed by Keefe and Block (1982) appears to better fit our data than the methodology utilized with RA subjects, this study suggests the need to refine this assessment tool for use with a FS sample. Clinical observations during this study suggested the develop- ment of 2 new pain behaviors. Two frequently observed behaviors included shifting weight from foot to foot (standing) or hip to hip (sitting), and flexing or stretch- ing painful areas, particularly the neck, shoulders, or back. Research to streamline the present pain behavior measure and add pain behaviors specific to FS patients

could potentially result in a more valid measure of pain behaviors for FS patients.

Some general limitations concerning our study and subject sample are noteworthy. The pain behavior data were skewed; therefore, all P values should be consid- ered approximations. In addition, our data was correla- tional, therefore causality could not be determined. This study does not address the demand characteristics of utilizing videotape equipment. Finally, our entire sample consisted of female patients; any potential gen- der effects remained unclear. The results and limita- tions of the present study suggest two major directions for related research. The first involves the pain behav- iors themselves. Results from the present study strongly suggested that the pain behavior measure needs to be refined to better ‘fit’ FS patients. The second direction for future research involves the choice of predictor variables. There exist a number of potential variables that may be useful to examine in a predictive model. These include medical status variables (e.g., myalgic scores), psychological variables (e.g., self-efficacy), and environmental factors (e.g., family reinforcement for pain behavior).

In spite of its limitations, the results of the present study indicate the importance of pain behaviors and the potential usefulness of this assessment tool with fibromyalgia patients. The pain behavior methodology may help objectively define FS pain, elucidate influ- ences on pain behavior, suggest areas of intervention to decrease maladaptive pain behaviors and increase adaptive well behaviors, and allow clinicians to observe directly the changes and progress patients make, rather than relying solely on self-report measures.

Acknowledgements

The authors gratefully acknowledge assistance pro- vided by William E. Deuser, Jerry Parker, and Joan Peterson inthe preparation of this manuscript.

This research was supported in part by a Center Grant from National Institute on Disability and Reha- bilitation Research (H133B80075) and by National In- stitute of Health - National Institute of Arthritis and Musculoskeletal and Skin Diseases First Independent Research Support and Transition Award (DHHS l- R29-AR39481).

References

Ahles, T.A., Yunus, M.B., Riley, S.D., Bradley, J.M. and Masi, A.T., Psychological factors associated with primary fibromyalgia syn- drome, Arthr. Rheum., 27 (1984) 1101-1106.

Ahles, T.A., Yunus, M.B. and Masi, A.T., Is chronic pain a variant of depressive disease? The case of fibromyalgia syndrome, Pain, 29 (1987) 105-111.

345

Anderson, K.O., Bradley, L.A., McDaniel, L.K., Young, L.D., Turner, R.A., Agudelo, CA., Keefe, F.J., Pisko, E.J., Snyder, R.M. and Semble, E.L., The assessment of pain in rheumatoid arthritis: validity of a behavioral observation method, Arthr. Rheum., 30 (1987a) 36-43.

Anderson, K.O., Bradley, L.A., McDaniel, L.K., Young, L.D., Turner, R.A., Agudelo, C.A., Gahy, N.S., Keefe, F.J., Pisko, E.J., Snyder, R.M. and Semble, E.L., The assessment of pain in rheumatoid arthritis: disease differentiation and temporal stability of a behav- ioral observation method, J. Rheumatol., 14 (1987b) 700-704.

Anderson, K.O., Keefe, F.J., Bradley, L.A., McDaniel, L.K., Young, L.D., Turner, R.A., Agudelo, C.A., Semble, E.L. and Pisko, E.J., Prediction of pain behavior and functional status of rheumatoid arthritis patients using medical status and psychological variables, Pain, 33 (1988) 25-32.

Anderson, K.O., Bradley, L.A., Turner, R.A., Agudelo, C.A., Pisko, E.J. and Salley, A.N., Variability of arthritis pain behavior in clinical practice and laboratory settings (abstract), Paper pre- sented at the 8th annual meeting of the American Pain Society, 1989.

Buescher, K.L., Johnston, J.A., Parker, J.C., Smarr, K.L., Buckelew, S.P., Anderson, S.K. and Walker, S.E., Relationship of self-ef- ficacy to pain behavior, J. Rheumatol., 18 (1991) 968-972.

Byrne, M., Troy, A., Bradley, L., Marchisello, P., Geisinger, K., Van der Heide, L. and Prieto, E., Cross-validation of the factor structure of the McGill Pain Questionnaire, Pain, 13 (19821 193-201.

Cathey, M.A., Wolfe, F., Kleinheskel, S.M. and Hawley, D.J., So- cioeconomic impact of fibrositis, Am. J. Med., 81 (Suppl 3A) (1986) 78-84.

Clark, S., Campbell, SM., Forehand, M.E., Tindall, E.A. and Ben- nett, R.M., Clinical characteristics of fibrositis. II. A ‘blinded’ controlled study using standard psychological tests, Arthr. Rheum., 28 (1985) 132-137.

Derogatis, L.R., SCL-90-R administration, scoring, and procedures manual, Chn. Psychomet. Res., Towson, MD, 1977.

Fordyce, W.E., Behavioral methods for chronic pain and illness, C.V. Mosby, St. Louis, MO, 1976.

Fordyce, W.E., Lansky, D., Calsyn, D.A., Shelton, J.L., Stolov, WC. and Rock, D.L., Pain measurement and pain behavior, Pain, 18 (1984) 53-69.

Graham, C., Bond, S.S., Gerkovich, M.M. and Cook, M.R., Use of the McGill Pain questionnaire in the assessment of cancer pain: replicability and consistency, Pain, 8 (1980) 377-387.

Hawley, D., Wolfe, F. and Cathey, M.A., Pain, functional disability, and psychological status: a 12-month study of severity in fi- bromyalgia, J. Rheumatol., 15 (1988) 1551-1556.

Hawley, D.J. and Wolfe, F., Pain, disability, and pain/disability relationships in seven rheumatic disorders: a study of 1552 pa- tients, J. Rheumatol., 18 (1991) 1552-1557.

Hunter, M., Philips, C. and Rachman, S., Memory for pain, Pain, (1979) 35-46.

Keefe, F.J. and Block, A.R., Development of an observation method for assessing pain behavior in chronic low back pain patients, Behav. Ther., 13 (1982) 363-375.

Keefe, F.J., Wilkins, R.H., Cook, W.A., Crisson, J.E. and Muhlbaier, L.H., Depression, pain, and pain behavior, J. Consult. Chn. Psychol., 54 (1986) 665-669.

Keefe, F.J., Caldwell, D.S., Queen, K., Gil, K.M., Martinez, S., Crisson, J.E., Ogden, W. and Nunley, J., Osteoarthritic knee pain: a behavioral analysis, Pain, 28 (1987) 309-321.

Leavitt, F. and Katz, R.S., Is the MMPI invalid for assessing psycho- logical disturbance in pain related organic conditions?, J. Rheumatol., 16 (1989) 521-526.

Lee, P.S.C. and Suen, H.K., The estimation of kappa from percent- age agreement interobserver reliability, Behav. Assess., 6 (1984) 375-378.

346

McDanieI, L.K., Anderson, KO., Bradley, L.A., Young, L.D., Turner, R.A., Agudelo, C.A. and Keefe, F.J., Development of an observa- tion method for assessing pain behavior in rheumatoid arthritis patients, Pain, 24 (1986) 165-184.

Meenan, R.F., Gertman, P.M. and Mason, J.H., Measuring health status in arthritis. The arthritis impact measurement scales, Arthr. Rheum., 23 (1980) 146-152.

Meenan, R.F., Anderson, J.J., Kazis, L.E., Egger, M.A., Samuelson, C.O., Jr., Wilkins, R.F., Solsky, M.A., Hayes, S.P., Blocka, K.L., Weinstein, M.G., Kaplan, S.B. and Klippel, J., Outcome assess- ment in clinical trials. Evidence for the sensitivity of a health status measure, Arthr. Rheum., 27 (1984) 1344-1352.

Melzack, R., The McGill Pain Questionnaire: major properties and scoring methods, Pain, 1 (19751277-299.

Millard, R.W., ‘Ihe Functional Assessment Screening Questionnaire: application for evaluating pain-related disability, Arch. Phys. Med. Rehab., 70 (1989) 303-307.

Payne, T.C., Leavitt, F., Garron, DC., Katz, R.S., Golden, H.E., Glickman, P.B. and Vanderplate, C., Fibrositis and psychologic disturbance, Arthr. Rheum., 25 (1982) 213-217.

Russell, I.J., Fletcher, E.M., Tsui, J. and Michalek, J.E., Compar- isons of rheumatoid arthritis and fibrositis/fibromyaIgia syn- drome using functional and psychological outcome measures, Arthr. Rheum., 32 (Suppl. 41fl989) 570.

Scudds, R.A., Rollman, G.B., Harth, M. and McCain, G.A.. Pain

perception and personality measures as discriminators in the classification of fibrositis, J. Rheumatol., 14 (1987) 563-569.

Tait, R.C., Chibnall, J.T. and Krause, S., The Pain Disability Index: psychometric properties, Pain, 40 (1990) 171-182.

Uveges, J.M., Parker, J.C., Smarr, K.L., McGowan, J.F., Lyon, M.G., Irvin, W.S., Meyer, A.A., Buckeiew, S.P., Morgan, R.K., Del- monico, R.L., Hewett, J.E. and Kay, D.R., Psychological symp- toms in primary fibromyalgia syndrome: relationship to pain, life stress, and sleep disturbance, Arthr. Rheum., 33 (1990) 1279- 1283.

Wolfe, F., Cathey, M.A. and Kleinheskel, S.M., Fibrositis (fibromyalgia) in rheumatoid arthritis, J. Rheumatol., 11 (1984a) 814-818.

Wolfe, F., Cathey, M.A., ~einheskel, S.M., Amos, S.P., Hoffman, R.G., Young, D.Y. and Hawley, D.J., Psychological status in primary fibrositis and fibrositis associated with rheumatoid arthri- tis, J. Rheumatol., 11 (1984b) 500-506.

Wysenbeek, A.J., Mor, F., Lurie, Y. and Weinberger, A., Imipramine for the treatment of fibrositis: a therapeutic trial, Ann. Rheum. Dis., 44 (1985) 752-753.

Yunus, M.B., Primary ~bromyaigia syndrome: current concepts, Compr. Ther., 10 (1984) 21-28.

Yunus, M.B., Masi, A.T. and Aldag, J.C., Criteria studies of primary fibrositis, Arthr. Rheum., 30 (1987) S50.