Behav. Res. The. Vol. 30,No. I,pp.71-73,1992 Printed in Great Britain. All rights reserved
Copyright
0
OOOS-7967/92 $5.00 + 0.00 1991 Pergamon Press pie
Efficient pain assessment in clinical settings SANDY
E. GRAMLING
and TIMOTHYR. ELLIC~TT
Department of Psychology, Virginia Commonwealth University, Richmond, VA 23284-2018, U.S.A. (Received 28 February 199ij
Summary-The need for efficient and practical assessment techniques of the multidimensional nature of chronic pain remains paramount in clinical settings. Visual analogue scales (VASs) and simple behavioral observation methods have been proposed as efficient, reliable, and valid measures of the subjective (sensory and affective) and overt behavioral aspects of the pain experience. The relationships among VASs and the UAB Pain Behavior Scale were examined among 48 chronic pain patients. Ratings of overt behavior were significantly related to both the VAS sensory and VAS affective ratings. Regression analysis indicated that the VAS scores accounted for significant amount of the variance (27.7%) in UAB scores. Moreover, the affective dimension of self-reported pain tended to be more strongly related to the visible manifestations of pain than were ratings of pain intensity.
There is widespread agreement that pain is a multi-dimensional phenomenon which requires multi-modal assessment. Numerous measurement devices have been constructed to assess the multi-faceted aspects of both the subjective (e.g. Melzack, 19X), and overt behavioral aspects of pain (e.g. Keefe and Block, 1982). When administers properly, many of these instruments are valid and reliable. However, the use of complicated questionnaires, sophisticated observation techniques, and time-consuming interviews have been criticized as unwieldy in general clinical practice (e.g. Ahles, Ruckdeschel & Blanchard, 1984; Feuerstein, Labbe & Kuczmierczyk, 1986). In the context of the clinical setting, the need for measurement procedures that are eficient, as well as reliable and valid remains paramount (Caplan, 1987). The present paper examines the relationship between two reportedly very practical measures of the subjective and overt behavioral aspects of pain. Together, these measures describe multiple parameters of the pain experience in a very efficient manner. With respect to the subjective aspects of pain, cogent arguments have been made that Visual Analogue Scales (VASs) meet the three essential criteria for meaningful quantitative comparisons of human pain. The VASs provide ratio scale measurement of the subjective aspects of the pain experience and are used in a consistent manner across different types of pain populations (e.g. Cracely, McGrath & Dubner, 1978; Harkins, Price & Martelli, 1986; Price, McGrath, Rash & Buckingham, 1983; Price & Harkins, 1987). These features permit comparisons of the relative intensities of different types of pain as well as percent changes in intensity and therefore have great utility for evaluating patient progress during treatment. In the context of multi-modal assessment of pain, it is important to note that separate VASs measuring the sensory-intensive and the affective-motivational aspects of pain are demonstrably independent of each other (Price & Harkins, 1987; Price, Harkins & Baker, 1987). Importantly, the VASs are easy to administer and score, requiring only minutes to obtain valid, reliable assessments of subjective pain. The use of behavioral observation techniques to assess overt pain behavior has become an integral component of the multi-modal pain assessment perspective (Keefe & Gil, 198.5; Keefe, 1989). Info~ation obtained from these measures provides the clinician with a rich source of information not obtainable through self-report measures alone. Numerous behavioral observation procedures for various populations have been developed in recent years (McDaniel et al., 1986; Jensen, Bradley & Linton, 1989; Keefe, Bradley & Crisson, 1990). Though there is ample evidence that these procedures are reliable and valid. most reouire video-taping patients and tedious post-hoc scoring of tapes. The UAB Pain Behavior Scale (UAB) has been heralded as a behaviors rating form designed to be adm~istere~ quickly and efhciently by hosnital/team nersonnel with verv little training (Richards. Nenomuceno, Riles & Suer, 1982). The inter-rater reliability and temporal stability of the instrument are q&e good and the instrument takes only 5 min. to administer (Richards kt al., 1982). There have been numerous reports in the literature examining the relationships among various self-report measures of pain and observational measures of pain. However, there have been only a few reports comparing the relationship between VASs and behavioral observation techniques (Ahles, Coombs, Jensen, Stukel, Maurer & Keefe, 1990; Keefe & Block, 1982; McDaniel er al., 1986; Richards et al., 1982; Romano, Syrjala, Levy, Turner, Evans & Keefe, 1988). The strength of the relationship between VAS pain ratings and overt behavior reported in these studies has varied from insienilicant to moderate. Onlv one of these studies examined the UAB and the VAS ratings of subjective pain (Richards 2 al., 1982). Unfortunately, this report employed only a sensory VAS pain rating scale (Richards et al., 1982). In the context of clinicians’ need for efhcient multi-modal pain assessment, an examination of the relationships among VAS ratings of the sensory and affective dimensions of pain with observational ratings of pain behavior seems warranted. VAS ratinns of pain unplea~ntness (affective domain) are influenced by personality variables such as neuroticism, whereas VAS ratings of pain intensity are not (Harkins, Price & Braith, 1989). Overt pain behavior has long been thought to be influenced by similar personality characteristics (Keefe, 1989). Presumably then, ratings of overt pain behavior are likely to be more strongly related to the affective, relative to the sensory, VAS measures of pain. 71
12
CASE HISTORIES
AND
SHORTER
COMMUNICATIONS
METHODS Subjects A heterogenous sample of 48 adult chronic pain patients (27 men, 21 women) were recruited from two out-patient pain management clinics located in a large metropolitan area. The mean age of the sample was 43.4 yr (SD = 14 yr) and the mean duration of pain was 3.7 yr (SD = 5.5 yr). Measures UAB pain behaoior scale. The UAB pain behavior scale is a IO-item pain behavior rating form which was designed to be administered quickly and efficiently by hospital/team personnel (Richards et al., 1982). The pain behaviors include verbal and nonverbal vocal complaints, down-time, facial grimaces, standing posture, mobility, body language, use of visible supportive equipment, stationary movement and medication usage. Raters are trained to rate these behaviors against specific criteria using a scale of none, occasional and frequently occurring, with corresponding point values of 0, l/2, and 1. The inter-rater reliability (0.95) and temporal stability (0.89) of the instrument are quite good (Richards et al., 1982). Visual Analogue Scale CyAS). The VAS scales and instructions were adopted from Price and Harkins (1987). The scales were comprised of separate horizontal straight lines 150 mm in length. The sensory intensive scale (VAS-I) was anchored on the left with the descriptive phrase ‘no sensation’ and on the right with the phrase ‘most intense sensation imaginable’. The affective motivational scale (VAS-U) was anchored on the left with the descriptive phrase ‘not at all unpleasant’ and on the right with the phrase ‘most unpleasant sensation imaginable’. Patients made a vertical mark on the VAS at the point that indicated their level of pain intensity and associated unpleasantness. The scale was scored by mesuring to the nearest millimeter the distance between the left endpoint and the patient’s mark. Procedures Two research assistants were trained to administer the VASs and rate pain behavior with the UAB in a 30 min training session. At designated times one of the two research assistants approached patients in the waiting room in one of two pain management clinics and invited the patient to participate in a ‘brief study aimed at increasing our understanding of chronic pain’. Occasionally, the two research assistants would evaluate the same patient together in order to insure that they were rating pain behaviors in a consistent and reliable manner (Bradley, Prokop, Gentry, Van der Heide & Prieto, 1981). After the procedures were described and the participant had signed a consent form, the research assistant conducted a brief interview. Demographic information was obtained as well as down-time and medication usage. Patients were asked to walk a short distance, stand still momentarily, and move from a sitting to a standing position and vice versa in accordance with the recommended procedures for use of the UAB (Richards et al., 1982). The pain behavior ratings were recorded at this time. The patient was then presented the VAS-I rating form, followed by the VAS-U rating form. These procedures, including reading and signing the consent form took approx. 15 min. RESULTS Table 1 presents the correlation matrix, means and standard deviations and the results of standard regression procedures predicting overt pain behaviors (UAB scores) from self-report measures of pain (VAS-I and VAS-U scores). In general, patients reported moderately intense levels of pain (mean VAS-I = 62.0 mm) with somewhat higher ratings on the unpleasantness dimension (mean VAS-U = 71.0 mm). Pain ratings based on overt behavior tended towards lower scores (mean UAB score = 2.5 on a 10 point scale). Both the VAS-I and VAS-U pain ratings were significantly correlated with the behavioral ratings of pain, r = 0.47, and r = 0.53, respectively. Though there was a tendency for the VAS-U scores to be more strongly related to UAB scores relative to VAS-I scores, a test for differences between correlations from dependent samples was not significant (z = 1.3, P > 0.05; Glass & Stanley, 1970). When the VAS-I and VAS-U ratings were entered into a standard regression equation (Tabachnick & Fidel], 1989) to predict UAB ratings, the overall model was significant, R2 = 0.278, F(2,45) = 8.66, P < 0.001, indicating that combined, the two VASs accounted for 27.8% of the variance in scores of overt pain behavior. The VAS-U variable entered the equation first and accounted for 7.7% of the unique variance in UAB scores. The unique variance in UAB scores attributable to VAS-U scores approached but did not reach statistical significance (t = 1.93, d.f. = 44, P i 0.06). The VAS-I variable entered second and added little in unique variance (0.1%). The shared variability in these two IVs equalled 20%. This degree of shared variance is not surprising given the high correlation between the two IVs (r = 0.91). DISCUSSION
These results suggest that valid multi-modal assessment of chronic pain can be accomplished efficiently and reliably in virtually any clinical setting. The relationships obtained among the variables in the present study are consistent with those reported elsewhere which employed more cumbersome assessment procedures. Specifically, McDaniel et al. (1986) used a videotape procedure to obtain observational ratings of pain behavior among 53 rheumatoid arthritis patients and correlated these scores with self-report VAS-I ratings and VAS-U ratings. The correlations obtained, 0.26 and 0.32, respectively, were Table I. Standard
multiple regression predicting overt pain behaviors from subjective ratings of pain intensity
UAB CDV)
Variables VAS-U
0.53**
VAS-I Means SDS
0.47’1 2.50 1.90
VAS-U
VAS-I
and unpleasantness
B 0.229
0.911’ 71.00 48.30
-0.033 62.00 42.80
variability
= 0.078; shared variability
sr2 (Unique)
0.597
0.077
0.236 Adjusted
**p < 0.01. tUnique
B
= 0.20.
0.001 R* = 0.278t R2 = 0.246 R = 0.527**
CASE HISTORIES
AND SHORTER
~MMUNICATIONS
73
significant (P < 0.05) and revealed a pattern similar to that reported in the present study. Namely, affective ratings of pain tended to be more strongly related to pain behavior than ratings of pain intensity. Several studies have examined the relationship between various behavioral observation measures and VAS-I scales and have reported mixed results. Three studies reported little relationship between VAS-I scores and behavioral observation scores (Ahles er al., 1990; Richards et al., 1982; Roman0 et al., 1988) whereas two studies have reported significant correlations between these two measures (McDaniel et al., 1986; Keefe & Block, 1982). Moderate correlations between these two types of measurement procedures suggest that the measures tap a common, yet multi-faceted construct. The absence of a significant relationship between VASII ratings and behavioural ratings reported by others have been interpreted as reflecting the independence of the two types , While this exnlanation has -_ of pain _ measures (Ahles et nl.. 1990: Keefe, 1989). merit, a number of me~odologi~l differences between studies may also account for these differences. To prevent patient’s self-report of pain from biasing the behavioral ratings (and perhaps inflating the correlation between measures) it seems prudent to complete the behavioral ratings before administering self-report measures of pain (as in the present study). Similarly, when examining the relationship between multiple measures of the same construct it seems prudent to take measurements within close temporal proximity. In some studies the temporal relationship between VAS measures and measures of overt behavior is unclear (Ahles et al., 1990; Richards et al., 1982). Also, some studies which found weak correlations between types of measurement procedures used a retrospective VAS-I of the past week or averaged several VAS-I measures taken during the day (Ahles et al., 1990; Roman0 et al., 1988). As the self-report measure of pain intensity diverges from the temporal parameters of the period of behavioral observation, lower correlations between these measures should be expected. In the present study, the comparatively large correlations between self-report measures of pain, and ratings of the visible manifestations of pain, may well be due to the close temporal proximity of the assessments. Ackno~iedgemenf-This
research supported in part by NIMH grant R03-MH438410182 awarded to the first author. REFERENCES
Ahles, T. A., Ruckdeschel, J. C. & Blanchard, E. B. (1984). Cancer-related pain-II.
Assessment with visual analogue scales,
Journal of Psychosomatic Research, 28, 121-124.
Ahles, T. A., Coombs, D. W., Jensen, L., Stukel, T., Maurer, L. H. & Keefe, F. J. (1990). Development of a behavioral observation technique for the assessment of pain behaviors in cancer patients. Behavior Therapy, 21, 449-460. Bradley, L. A., Prokop, C. K., Gentry, W. D., Van der Heide, L. H. & Prieto, E. J. (1981). Assessment of chronic pain. In Prokop, C. K. & Bradley, L. A. (Eds), Medical psychology: Conrributions to behaaioral medicine (pp. O&00). New York: Academic Press. Caplan, B. (1987). Rehabi~ifation ps.veholog~l desk reference, Rockville, Md: Aspen Press. Feuerstein, M., Labbe, E. E. Oe.Kuczmierczyk, A. R. (1986). Health psyehoiugy: apsyclzobio~ogiea~perspe&f~ve. New York: London Press. Glass, G. V. & Stanley, J. C. (1970). Statistical methods in education andpsychology. Englewood Cliffs, N.J.: Prentice Hall. Gracely, R. H., McGrath, P. & Dubner, R. (1978). Ratio scales of sensory and affective pain descriptors. Pain, 5, 5-18. Harkins, S. W., Price, D. D. & Braith, J. (1989). Effects of extraversion and neuroticism on experimental pain, clinical pain, and illness behavior. Pain, 36, 2099218. Harkins, S. W., Price, D. D. & Martelli, M. (1986). Effects of age on pain perception: Thermonociception. Journal of Geronfology, 41, 58-63.
Jensen, I. B., Bradley, L. A. & Linton, S. J. (1989). Validation of an observation method of pain assessment in non-chronic back pain. Pain, 39, 267-274. Keefe, F. J. (1989). Behavioral measurement of pain. In Chapman, C. R. & Loeser, J. D. (Eds), Issues in pain me~uremenf (pp. 405424). New York: Raven Press. Keefe, F. J. & Block, A. R. (1982). Development of an observation method for assessing pain behavior in chronic low back pain patients. Behavior Therapy, 13, 3633375. Keefe, F. J. & Gil, K. M. (1985). Recent advances in the behavioral assessment and treatment of chronic pain. Annals of Behavioral Medicine, 7, 1I-16. Keefe, F. J., Bradley, L. A. & Crisson, J. E. (1990). Behavioral assessment of low back pain: Identification of pain behavior subgroups. Pain, 44 153-160. McDaniel, L. K., Anderson, K. O., Bradley, L. A., Young, L. D., Turner, R. A., Agudelo, C. A. & Keefe, F. J. (1986). Development of an observation method for assessing pain behavior in rheumatoid arthritis patients. Pain, 24, 165-184. Melzack, R. (1975). The McGill Pain Questionnaire: Major properties and scoring methods. Pain, I, 277-299. Price, D. D. & Harkins, S. W. (1987). Combined use of experimental pain and visual analogue scales in providing standardized measurement of clinical pain. The Clinical Journal of Pam, 3, l-8. Price, D. D., Harkins, S. W. & Baker, C. (1987). Sensory-aff~tive relationships among different types of clinical and experimental pain. Pam, 28, 297-307. Price, D. D., McGrath, P. A., Rafii, A. & Buckingham, B. (1983). The validation of visual analogue scales as ratio scale measures for chronic and experimental pain. Pain, f7, 45-56. Richards, J. D., Nepomuceno, C., Riles, M. & Suer, Z. (1982). Assessing pain behavior: The UAB pain behavior scale. Pain, 14, 393-398.
Romano, J. M., Syrjala, K. L., Levy, R. A., Turner, .I. A., Evans, P. & Keefe, F. J. (1988). Overt pain behaviors: Relationship to patient functioning and treatment outcome. Behavior Therapy, 19, 191-201. Tabachnick, B. G. & Fidell, L. S. (1988). Using mulfivariare sfatislics (2nd edn). New York: Harper & Row.
Copyright
0
OOOS-7967/92 $5.00 + 0.00 1991 Pergamon Press pie
Efficient pain assessment in clinical settings SANDY
E. GRAMLING
and TIMOTHYR. ELLIC~TT
Department of Psychology, Virginia Commonwealth University, Richmond, VA 23284-2018, U.S.A. (Received 28 February 199ij
Summary-The need for efficient and practical assessment techniques of the multidimensional nature of chronic pain remains paramount in clinical settings. Visual analogue scales (VASs) and simple behavioral observation methods have been proposed as efficient, reliable, and valid measures of the subjective (sensory and affective) and overt behavioral aspects of the pain experience. The relationships among VASs and the UAB Pain Behavior Scale were examined among 48 chronic pain patients. Ratings of overt behavior were significantly related to both the VAS sensory and VAS affective ratings. Regression analysis indicated that the VAS scores accounted for significant amount of the variance (27.7%) in UAB scores. Moreover, the affective dimension of self-reported pain tended to be more strongly related to the visible manifestations of pain than were ratings of pain intensity.
There is widespread agreement that pain is a multi-dimensional phenomenon which requires multi-modal assessment. Numerous measurement devices have been constructed to assess the multi-faceted aspects of both the subjective (e.g. Melzack, 19X), and overt behavioral aspects of pain (e.g. Keefe and Block, 1982). When administers properly, many of these instruments are valid and reliable. However, the use of complicated questionnaires, sophisticated observation techniques, and time-consuming interviews have been criticized as unwieldy in general clinical practice (e.g. Ahles, Ruckdeschel & Blanchard, 1984; Feuerstein, Labbe & Kuczmierczyk, 1986). In the context of the clinical setting, the need for measurement procedures that are eficient, as well as reliable and valid remains paramount (Caplan, 1987). The present paper examines the relationship between two reportedly very practical measures of the subjective and overt behavioral aspects of pain. Together, these measures describe multiple parameters of the pain experience in a very efficient manner. With respect to the subjective aspects of pain, cogent arguments have been made that Visual Analogue Scales (VASs) meet the three essential criteria for meaningful quantitative comparisons of human pain. The VASs provide ratio scale measurement of the subjective aspects of the pain experience and are used in a consistent manner across different types of pain populations (e.g. Cracely, McGrath & Dubner, 1978; Harkins, Price & Martelli, 1986; Price, McGrath, Rash & Buckingham, 1983; Price & Harkins, 1987). These features permit comparisons of the relative intensities of different types of pain as well as percent changes in intensity and therefore have great utility for evaluating patient progress during treatment. In the context of multi-modal assessment of pain, it is important to note that separate VASs measuring the sensory-intensive and the affective-motivational aspects of pain are demonstrably independent of each other (Price & Harkins, 1987; Price, Harkins & Baker, 1987). Importantly, the VASs are easy to administer and score, requiring only minutes to obtain valid, reliable assessments of subjective pain. The use of behavioral observation techniques to assess overt pain behavior has become an integral component of the multi-modal pain assessment perspective (Keefe & Gil, 198.5; Keefe, 1989). Info~ation obtained from these measures provides the clinician with a rich source of information not obtainable through self-report measures alone. Numerous behavioral observation procedures for various populations have been developed in recent years (McDaniel et al., 1986; Jensen, Bradley & Linton, 1989; Keefe, Bradley & Crisson, 1990). Though there is ample evidence that these procedures are reliable and valid. most reouire video-taping patients and tedious post-hoc scoring of tapes. The UAB Pain Behavior Scale (UAB) has been heralded as a behaviors rating form designed to be adm~istere~ quickly and efhciently by hosnital/team nersonnel with verv little training (Richards. Nenomuceno, Riles & Suer, 1982). The inter-rater reliability and temporal stability of the instrument are q&e good and the instrument takes only 5 min. to administer (Richards kt al., 1982). There have been numerous reports in the literature examining the relationships among various self-report measures of pain and observational measures of pain. However, there have been only a few reports comparing the relationship between VASs and behavioral observation techniques (Ahles, Coombs, Jensen, Stukel, Maurer & Keefe, 1990; Keefe & Block, 1982; McDaniel er al., 1986; Richards et al., 1982; Romano, Syrjala, Levy, Turner, Evans & Keefe, 1988). The strength of the relationship between VAS pain ratings and overt behavior reported in these studies has varied from insienilicant to moderate. Onlv one of these studies examined the UAB and the VAS ratings of subjective pain (Richards 2 al., 1982). Unfortunately, this report employed only a sensory VAS pain rating scale (Richards et al., 1982). In the context of clinicians’ need for efhcient multi-modal pain assessment, an examination of the relationships among VAS ratings of the sensory and affective dimensions of pain with observational ratings of pain behavior seems warranted. VAS ratinns of pain unplea~ntness (affective domain) are influenced by personality variables such as neuroticism, whereas VAS ratings of pain intensity are not (Harkins, Price & Braith, 1989). Overt pain behavior has long been thought to be influenced by similar personality characteristics (Keefe, 1989). Presumably then, ratings of overt pain behavior are likely to be more strongly related to the affective, relative to the sensory, VAS measures of pain. 71
12
CASE HISTORIES
AND
SHORTER
COMMUNICATIONS
METHODS Subjects A heterogenous sample of 48 adult chronic pain patients (27 men, 21 women) were recruited from two out-patient pain management clinics located in a large metropolitan area. The mean age of the sample was 43.4 yr (SD = 14 yr) and the mean duration of pain was 3.7 yr (SD = 5.5 yr). Measures UAB pain behaoior scale. The UAB pain behavior scale is a IO-item pain behavior rating form which was designed to be administered quickly and efficiently by hospital/team personnel (Richards et al., 1982). The pain behaviors include verbal and nonverbal vocal complaints, down-time, facial grimaces, standing posture, mobility, body language, use of visible supportive equipment, stationary movement and medication usage. Raters are trained to rate these behaviors against specific criteria using a scale of none, occasional and frequently occurring, with corresponding point values of 0, l/2, and 1. The inter-rater reliability (0.95) and temporal stability (0.89) of the instrument are quite good (Richards et al., 1982). Visual Analogue Scale CyAS). The VAS scales and instructions were adopted from Price and Harkins (1987). The scales were comprised of separate horizontal straight lines 150 mm in length. The sensory intensive scale (VAS-I) was anchored on the left with the descriptive phrase ‘no sensation’ and on the right with the phrase ‘most intense sensation imaginable’. The affective motivational scale (VAS-U) was anchored on the left with the descriptive phrase ‘not at all unpleasant’ and on the right with the phrase ‘most unpleasant sensation imaginable’. Patients made a vertical mark on the VAS at the point that indicated their level of pain intensity and associated unpleasantness. The scale was scored by mesuring to the nearest millimeter the distance between the left endpoint and the patient’s mark. Procedures Two research assistants were trained to administer the VASs and rate pain behavior with the UAB in a 30 min training session. At designated times one of the two research assistants approached patients in the waiting room in one of two pain management clinics and invited the patient to participate in a ‘brief study aimed at increasing our understanding of chronic pain’. Occasionally, the two research assistants would evaluate the same patient together in order to insure that they were rating pain behaviors in a consistent and reliable manner (Bradley, Prokop, Gentry, Van der Heide & Prieto, 1981). After the procedures were described and the participant had signed a consent form, the research assistant conducted a brief interview. Demographic information was obtained as well as down-time and medication usage. Patients were asked to walk a short distance, stand still momentarily, and move from a sitting to a standing position and vice versa in accordance with the recommended procedures for use of the UAB (Richards et al., 1982). The pain behavior ratings were recorded at this time. The patient was then presented the VAS-I rating form, followed by the VAS-U rating form. These procedures, including reading and signing the consent form took approx. 15 min. RESULTS Table 1 presents the correlation matrix, means and standard deviations and the results of standard regression procedures predicting overt pain behaviors (UAB scores) from self-report measures of pain (VAS-I and VAS-U scores). In general, patients reported moderately intense levels of pain (mean VAS-I = 62.0 mm) with somewhat higher ratings on the unpleasantness dimension (mean VAS-U = 71.0 mm). Pain ratings based on overt behavior tended towards lower scores (mean UAB score = 2.5 on a 10 point scale). Both the VAS-I and VAS-U pain ratings were significantly correlated with the behavioral ratings of pain, r = 0.47, and r = 0.53, respectively. Though there was a tendency for the VAS-U scores to be more strongly related to UAB scores relative to VAS-I scores, a test for differences between correlations from dependent samples was not significant (z = 1.3, P > 0.05; Glass & Stanley, 1970). When the VAS-I and VAS-U ratings were entered into a standard regression equation (Tabachnick & Fidel], 1989) to predict UAB ratings, the overall model was significant, R2 = 0.278, F(2,45) = 8.66, P < 0.001, indicating that combined, the two VASs accounted for 27.8% of the variance in scores of overt pain behavior. The VAS-U variable entered the equation first and accounted for 7.7% of the unique variance in UAB scores. The unique variance in UAB scores attributable to VAS-U scores approached but did not reach statistical significance (t = 1.93, d.f. = 44, P i 0.06). The VAS-I variable entered second and added little in unique variance (0.1%). The shared variability in these two IVs equalled 20%. This degree of shared variance is not surprising given the high correlation between the two IVs (r = 0.91). DISCUSSION
These results suggest that valid multi-modal assessment of chronic pain can be accomplished efficiently and reliably in virtually any clinical setting. The relationships obtained among the variables in the present study are consistent with those reported elsewhere which employed more cumbersome assessment procedures. Specifically, McDaniel et al. (1986) used a videotape procedure to obtain observational ratings of pain behavior among 53 rheumatoid arthritis patients and correlated these scores with self-report VAS-I ratings and VAS-U ratings. The correlations obtained, 0.26 and 0.32, respectively, were Table I. Standard
multiple regression predicting overt pain behaviors from subjective ratings of pain intensity
UAB CDV)
Variables VAS-U
0.53**
VAS-I Means SDS
0.47’1 2.50 1.90
VAS-U
VAS-I
and unpleasantness
B 0.229
0.911’ 71.00 48.30
-0.033 62.00 42.80
variability
= 0.078; shared variability
sr2 (Unique)
0.597
0.077
0.236 Adjusted
**p < 0.01. tUnique
B
= 0.20.
0.001 R* = 0.278t R2 = 0.246 R = 0.527**
CASE HISTORIES
AND SHORTER
~MMUNICATIONS
73
significant (P < 0.05) and revealed a pattern similar to that reported in the present study. Namely, affective ratings of pain tended to be more strongly related to pain behavior than ratings of pain intensity. Several studies have examined the relationship between various behavioral observation measures and VAS-I scales and have reported mixed results. Three studies reported little relationship between VAS-I scores and behavioral observation scores (Ahles er al., 1990; Richards et al., 1982; Roman0 et al., 1988) whereas two studies have reported significant correlations between these two measures (McDaniel et al., 1986; Keefe & Block, 1982). Moderate correlations between these two types of measurement procedures suggest that the measures tap a common, yet multi-faceted construct. The absence of a significant relationship between VASII ratings and behavioural ratings reported by others have been interpreted as reflecting the independence of the two types , While this exnlanation has -_ of pain _ measures (Ahles et nl.. 1990: Keefe, 1989). merit, a number of me~odologi~l differences between studies may also account for these differences. To prevent patient’s self-report of pain from biasing the behavioral ratings (and perhaps inflating the correlation between measures) it seems prudent to complete the behavioral ratings before administering self-report measures of pain (as in the present study). Similarly, when examining the relationship between multiple measures of the same construct it seems prudent to take measurements within close temporal proximity. In some studies the temporal relationship between VAS measures and measures of overt behavior is unclear (Ahles et al., 1990; Richards et al., 1982). Also, some studies which found weak correlations between types of measurement procedures used a retrospective VAS-I of the past week or averaged several VAS-I measures taken during the day (Ahles et al., 1990; Roman0 et al., 1988). As the self-report measure of pain intensity diverges from the temporal parameters of the period of behavioral observation, lower correlations between these measures should be expected. In the present study, the comparatively large correlations between self-report measures of pain, and ratings of the visible manifestations of pain, may well be due to the close temporal proximity of the assessments. Ackno~iedgemenf-This
research supported in part by NIMH grant R03-MH438410182 awarded to the first author. REFERENCES
Ahles, T. A., Ruckdeschel, J. C. & Blanchard, E. B. (1984). Cancer-related pain-II.
Assessment with visual analogue scales,
Journal of Psychosomatic Research, 28, 121-124.
Ahles, T. A., Coombs, D. W., Jensen, L., Stukel, T., Maurer, L. H. & Keefe, F. J. (1990). Development of a behavioral observation technique for the assessment of pain behaviors in cancer patients. Behavior Therapy, 21, 449-460. Bradley, L. A., Prokop, C. K., Gentry, W. D., Van der Heide, L. H. & Prieto, E. J. (1981). Assessment of chronic pain. In Prokop, C. K. & Bradley, L. A. (Eds), Medical psychology: Conrributions to behaaioral medicine (pp. O&00). New York: Academic Press. Caplan, B. (1987). Rehabi~ifation ps.veholog~l desk reference, Rockville, Md: Aspen Press. Feuerstein, M., Labbe, E. E. Oe.Kuczmierczyk, A. R. (1986). Health psyehoiugy: apsyclzobio~ogiea~perspe&f~ve. New York: London Press. Glass, G. V. & Stanley, J. C. (1970). Statistical methods in education andpsychology. Englewood Cliffs, N.J.: Prentice Hall. Gracely, R. H., McGrath, P. & Dubner, R. (1978). Ratio scales of sensory and affective pain descriptors. Pain, 5, 5-18. Harkins, S. W., Price, D. D. & Braith, J. (1989). Effects of extraversion and neuroticism on experimental pain, clinical pain, and illness behavior. Pain, 36, 2099218. Harkins, S. W., Price, D. D. & Martelli, M. (1986). Effects of age on pain perception: Thermonociception. Journal of Geronfology, 41, 58-63.
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