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Pain measurement: A comparison using horizontal and vertical visual analogue scales
Research Brief Pain Measurement: A Comparison Using Horizontal and Vertical Visual Analogue Scales Nancy L. Stephenson and JoAnne Herman
The McGill Pain Questionnaire (MPQ) is widely used in assessing a variety of pain problems. MPQ has been found to be sensitive enough to detect differences in pain relief and differences between acute and chronic pain. It requires, however, 5 to 10 minutes to administer. Because of this time factor, the Short-Form McGill Pain Questionnaire (SF-MPQ) was developed. A visual analogue scale (VAS) was not included in the original MPQ but is part of the SF-MPQ. Studies addressing the best way to present a VAS suggest that a vertical line is easier for patients to see; however, the VAS on the SF-MPQ is a horizontal line. This study examined the relationship between SF-MPQ scores with both the horizontal and vertical VAS. Copyright r 2000 by W.B. Saunders Company
T
HE MCGILL PAIN QUESTIONNAIRE (MPQ), developed in 1975 by Ronald Melzack, is widely used to measure pain (Melzack, 1987; Reading, 1982; Wilkie, Savedra, Holzemer, Tesler & Paul, 1990). MPQ is useful in assessing a variety of pain problems (Camp & Sullivan, 1985; Kremer & Atkinson, 1981; Stephenson, 1994), and Melzack (1975) found MPQ to be sensitive enough to detect differences in pain relief. Furthermore, MPQ detects differences between acute and chronic pain (Reading, 1982; Wilkie et al., 1990). MPQ is valid, reliable, and versatile (Chapman et al., 1985; McGuire, 1984; McGuire, 1988), but it requires 5 to10 minutes to administer and uses 78 words to describe pain quality (Wilkie et al., 1990). Because of the time required to administer the instrument, Melzack (1987) developed the ShortForm McGill Pain Questionnaire (SF-MPQ), which has correlations of r ⫽ .62 to .90 with MPQ on the sensory and affective domains (Melzack, 1987). The present pain intensity (PPI) items on SF-MPQ are unchanged from MPQ; but a visual analogue scale (VAS), which was not included in the original MPQ, is part of the SF-MPQ. The VAS is a 10-centimeter line with verbal anchors, ‘‘no pain’’ to ‘‘worst possible pain.’’ Studies addressing the best way to present a VAS suggest that a vertical line is easier for patients to see, especially if stress
Applied Nursing Research, Vol. 13, No. 3 (August), 2000: pp 157-158
is causing a narrowed visual field (Gift, 1989).The VAS on SF-MPQ, however, is a horizontal line (Melzack, 1987). Therefore this study examined the relationship between SF-MPQ scores with the horizontal VAS and scores using the vertical VAS. METHODS
To compare the horizontal VAS SF-MPQ (simply, SF-MPQ) with the vertical VAS SF-MPQ (SF-MPQv), a convenience sample of 21 faculty and students at two universities in the southeastern United States was selected. The VAS was the same 10-centimeter analogue in both tests. Demographic data were collected on race, gender, and age. Subjects completed SF-MPQ or SF-MPQv to describe a pain experience in their past. Forty-five minutes later, the group that had initially used the
Nancy L. Stephenson, PhD, RN, CS, East Carolina University, School of Nursing, Greenville, NC; JoAnne Herman, PhD, University of South Carolina, College of Nursing, Columbia, SC. Address reprint requests to Nancy L. Stephenson, PhD, RN, CS, Assistant Professor, East Carolina University, School of Nursing, Greenville, NC 27858-4353. E-mail: stephensonn@ mail.ecu.edu. Copyright r 2000 by W.B. Saunders Company 0897-1897/00/1303-0006$10.00/0 doi:10.1053/apnr.2000.7658 157
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STEPHENSON AND HERMAN
test with the horizontal VAS was asked the same information but used the test with the vertical VAS—and vice versa—to determine if the two tests yielded equivalent results. Subjects could seek clarification by asking questions; however, subjects asked very few questions. Subjects were asked to label the type of pain they were describing and given examples such as labor or dental pain. Ten of the subjects received SF-MPQ first and the other 11 subjects received SF-MPQv first, to prevent bias from the ordering of the test or systematic error (Waltz, Strickland & Lenz, 1991). Subjects were assigned a number to pair the tests and to maintain confidentiality of the subject’s responses. Scoring involved measuring the 10-centimeter line to determine the numerical quality of pain, which could range from 1 to 10. The PPI scores were also recorded. Paired t tests were used to compare SF-MPQ to SF-MPQv and to compare VAS scores to PPI scores. RESULTS
The 21 subjects’ ages ranged from 18 to 50 years. Racial composition of the sample was 5 black and 16 white subjects. Only two of the subjects were males. Pain experiences described were dental (28.6%), abdominal (28.6%), orthopedic (19%), labor (14.3%), and post-operative (9.5%). The subjects had a higher mean score (6.99) on SF-MPQv than on SF-MPQ (6.90). There was a correlation of .8 between the VAS on SF-MPQv and SF-MPQ, and that correlation was statistically significant, p ⫽ ⬍.01.
It was interesting to note that SF-MPQv correlated better with PPI at .71 than did SF-MPQ with PPI at .64. All correlations were statistically significant at p ⫽ .01. DISCUSSION
SF-MPQ has been administered to patients with labor, menstrual, headache, phantom, post-herpetic, dental, cancer, arthritic, post-surgical, musculoskeletal, and low-back pain (Melzack, 1987). Although this sample of 21 subjects was too small to generalize on specific types of pain, the types of pain in this study were similar to those measured in previous studies. The study should be repeated with a larger sample and with patients at the actual time of pain to determine whether patients consistently rate themselves higher on SF-MPQv. Retrospective self-report of pain is less desirable than a report at the time of the pain, given the variability of remembering. The vertical VAS component of SF-MPQv had a higher correlation with PPI than the horizontal VAS component of SF-MPQ. Overall, SF-MPQ was time efficient and provided useful information; but SF-MPQv had the same advantages in addition to having the improved VAS. The improved accuracy of the vertical VAS would be helpful in evaluating pain. In addition, SF-MPQv would make instrument administration and scoring easier for busy clinicians (Gift, 1989; Herr & Mobily, 1993).
REFERENCES Camp, L.D., & Sullivan, P.O. (1987). Comparison of medical, surgical and oncology patients’ descriptions of pain and nurses’ documentations of pain assessment. Journal of Advanced Nursing, 12 (5), 593-598. Chapman, C.R., Casey, K.L., Dubner, R., Foley, K.M., Gracely, R.H., & Reading A.E. (1985). Pain measurement: An overview. Pain, 22(1), 1-31. Gift, A.G. (1989). Visual analogue scales: Measurement of subjective phenomena. Nursing Research, 38(5), 286-288. Kremer, E., & Atkinson, Jr., J.H. (1981). Pain measurement: Construct validity of the affective dimension of the MPQ with chronic benign pain patients. Pain, 11, 93-100. McGuire, D.B. (1988). Measuring pain. In M. FrankStromborg (Ed.) Instruments for Clinical Nursing Research (pp. 333-356). Norwalk, CN: Appleton & Lange. Melzack, R. (1975). The McGill Pain Questionnaire: Major properties and scoring methods. Pain, 1(1), 277-299.
Melzack, R. (1983). Pain Measurement and Assessment. New York: Raven Press. Melzack, R. (1987). The short-form McGill Pain Questionnaire. Pain,30, 191-197. Reading, A.E. (1982). A comparison of the McGill Pain Questionnaire in chronic and acute pain. Pain, 13, 185-192. Stephenson, N.L.N. (1994). A comparison of nurse and patient perceptions of patient’s postsurgical pain. Journal of Intravenous Nursing, 5 (17), 235-239. Waltz, F.C., Strickland, O.L., & Lenz, E.R. (1991). Measurement in Nursing Research. (2nd ed.). Philadelphia, PA: F.A. Davis Company. Wilkie D.J., Savedra, M.C., Holzemer, W.L., Tesler, M.D., & Paul, S M. (1990). Use of the McGill Pain Questionnaire to Measure Pain: A meta-analysis. Nursing Research, 39 (1), 36-41.
The McGill Pain Questionnaire (MPQ) is widely used in assessing a variety of pain problems. MPQ has been found to be sensitive enough to detect differences in pain relief and differences between acute and chronic pain. It requires, however, 5 to 10 minutes to administer. Because of this time factor, the Short-Form McGill Pain Questionnaire (SF-MPQ) was developed. A visual analogue scale (VAS) was not included in the original MPQ but is part of the SF-MPQ. Studies addressing the best way to present a VAS suggest that a vertical line is easier for patients to see; however, the VAS on the SF-MPQ is a horizontal line. This study examined the relationship between SF-MPQ scores with both the horizontal and vertical VAS. Copyright r 2000 by W.B. Saunders Company
T
HE MCGILL PAIN QUESTIONNAIRE (MPQ), developed in 1975 by Ronald Melzack, is widely used to measure pain (Melzack, 1987; Reading, 1982; Wilkie, Savedra, Holzemer, Tesler & Paul, 1990). MPQ is useful in assessing a variety of pain problems (Camp & Sullivan, 1985; Kremer & Atkinson, 1981; Stephenson, 1994), and Melzack (1975) found MPQ to be sensitive enough to detect differences in pain relief. Furthermore, MPQ detects differences between acute and chronic pain (Reading, 1982; Wilkie et al., 1990). MPQ is valid, reliable, and versatile (Chapman et al., 1985; McGuire, 1984; McGuire, 1988), but it requires 5 to10 minutes to administer and uses 78 words to describe pain quality (Wilkie et al., 1990). Because of the time required to administer the instrument, Melzack (1987) developed the ShortForm McGill Pain Questionnaire (SF-MPQ), which has correlations of r ⫽ .62 to .90 with MPQ on the sensory and affective domains (Melzack, 1987). The present pain intensity (PPI) items on SF-MPQ are unchanged from MPQ; but a visual analogue scale (VAS), which was not included in the original MPQ, is part of the SF-MPQ. The VAS is a 10-centimeter line with verbal anchors, ‘‘no pain’’ to ‘‘worst possible pain.’’ Studies addressing the best way to present a VAS suggest that a vertical line is easier for patients to see, especially if stress
Applied Nursing Research, Vol. 13, No. 3 (August), 2000: pp 157-158
is causing a narrowed visual field (Gift, 1989).The VAS on SF-MPQ, however, is a horizontal line (Melzack, 1987). Therefore this study examined the relationship between SF-MPQ scores with the horizontal VAS and scores using the vertical VAS. METHODS
To compare the horizontal VAS SF-MPQ (simply, SF-MPQ) with the vertical VAS SF-MPQ (SF-MPQv), a convenience sample of 21 faculty and students at two universities in the southeastern United States was selected. The VAS was the same 10-centimeter analogue in both tests. Demographic data were collected on race, gender, and age. Subjects completed SF-MPQ or SF-MPQv to describe a pain experience in their past. Forty-five minutes later, the group that had initially used the
Nancy L. Stephenson, PhD, RN, CS, East Carolina University, School of Nursing, Greenville, NC; JoAnne Herman, PhD, University of South Carolina, College of Nursing, Columbia, SC. Address reprint requests to Nancy L. Stephenson, PhD, RN, CS, Assistant Professor, East Carolina University, School of Nursing, Greenville, NC 27858-4353. E-mail: stephensonn@ mail.ecu.edu. Copyright r 2000 by W.B. Saunders Company 0897-1897/00/1303-0006$10.00/0 doi:10.1053/apnr.2000.7658 157
158
STEPHENSON AND HERMAN
test with the horizontal VAS was asked the same information but used the test with the vertical VAS—and vice versa—to determine if the two tests yielded equivalent results. Subjects could seek clarification by asking questions; however, subjects asked very few questions. Subjects were asked to label the type of pain they were describing and given examples such as labor or dental pain. Ten of the subjects received SF-MPQ first and the other 11 subjects received SF-MPQv first, to prevent bias from the ordering of the test or systematic error (Waltz, Strickland & Lenz, 1991). Subjects were assigned a number to pair the tests and to maintain confidentiality of the subject’s responses. Scoring involved measuring the 10-centimeter line to determine the numerical quality of pain, which could range from 1 to 10. The PPI scores were also recorded. Paired t tests were used to compare SF-MPQ to SF-MPQv and to compare VAS scores to PPI scores. RESULTS
The 21 subjects’ ages ranged from 18 to 50 years. Racial composition of the sample was 5 black and 16 white subjects. Only two of the subjects were males. Pain experiences described were dental (28.6%), abdominal (28.6%), orthopedic (19%), labor (14.3%), and post-operative (9.5%). The subjects had a higher mean score (6.99) on SF-MPQv than on SF-MPQ (6.90). There was a correlation of .8 between the VAS on SF-MPQv and SF-MPQ, and that correlation was statistically significant, p ⫽ ⬍.01.
It was interesting to note that SF-MPQv correlated better with PPI at .71 than did SF-MPQ with PPI at .64. All correlations were statistically significant at p ⫽ .01. DISCUSSION
SF-MPQ has been administered to patients with labor, menstrual, headache, phantom, post-herpetic, dental, cancer, arthritic, post-surgical, musculoskeletal, and low-back pain (Melzack, 1987). Although this sample of 21 subjects was too small to generalize on specific types of pain, the types of pain in this study were similar to those measured in previous studies. The study should be repeated with a larger sample and with patients at the actual time of pain to determine whether patients consistently rate themselves higher on SF-MPQv. Retrospective self-report of pain is less desirable than a report at the time of the pain, given the variability of remembering. The vertical VAS component of SF-MPQv had a higher correlation with PPI than the horizontal VAS component of SF-MPQ. Overall, SF-MPQ was time efficient and provided useful information; but SF-MPQv had the same advantages in addition to having the improved VAS. The improved accuracy of the vertical VAS would be helpful in evaluating pain. In addition, SF-MPQv would make instrument administration and scoring easier for busy clinicians (Gift, 1989; Herr & Mobily, 1993).
REFERENCES Camp, L.D., & Sullivan, P.O. (1987). Comparison of medical, surgical and oncology patients’ descriptions of pain and nurses’ documentations of pain assessment. Journal of Advanced Nursing, 12 (5), 593-598. Chapman, C.R., Casey, K.L., Dubner, R., Foley, K.M., Gracely, R.H., & Reading A.E. (1985). Pain measurement: An overview. Pain, 22(1), 1-31. Gift, A.G. (1989). Visual analogue scales: Measurement of subjective phenomena. Nursing Research, 38(5), 286-288. Kremer, E., & Atkinson, Jr., J.H. (1981). Pain measurement: Construct validity of the affective dimension of the MPQ with chronic benign pain patients. Pain, 11, 93-100. McGuire, D.B. (1988). Measuring pain. In M. FrankStromborg (Ed.) Instruments for Clinical Nursing Research (pp. 333-356). Norwalk, CN: Appleton & Lange. Melzack, R. (1975). The McGill Pain Questionnaire: Major properties and scoring methods. Pain, 1(1), 277-299.
Melzack, R. (1983). Pain Measurement and Assessment. New York: Raven Press. Melzack, R. (1987). The short-form McGill Pain Questionnaire. Pain,30, 191-197. Reading, A.E. (1982). A comparison of the McGill Pain Questionnaire in chronic and acute pain. Pain, 13, 185-192. Stephenson, N.L.N. (1994). A comparison of nurse and patient perceptions of patient’s postsurgical pain. Journal of Intravenous Nursing, 5 (17), 235-239. Waltz, F.C., Strickland, O.L., & Lenz, E.R. (1991). Measurement in Nursing Research. (2nd ed.). Philadelphia, PA: F.A. Davis Company. Wilkie D.J., Savedra, M.C., Holzemer, W.L., Tesler, M.D., & Paul, S M. (1990). Use of the McGill Pain Questionnaire to Measure Pain: A meta-analysis. Nursing Research, 39 (1), 36-41.