Commentary
Assessing Pain Intensity With the Visual Analog Scale: A Plea for Uniformity
The Journal of Clinical Pharmacology 54(3) 241–244 © 2014, The American College of Clinical Pharmacology DOI: 10.1002/jcph.250
Michael D. Reed, PharmD, FCCP, FCP1,2,3 and William Van Nostran, BS1 Keywords Visual analogue scale (VAS), pain scale, VAS validity, pain assessment
“Those who do not feel pain seldom think that it is felt.” Dr. Samuel Johnson (circa 1750)
The sensation of pain is undeniably subjective. Personality, recollections of painful events, emotional state, age, culture, context, and other factors influence an individual’s responses to, and description of, pain.1–5 Linguistically, the word “pain” encompasses multidimensional attributes well beyond a single sensation varying only in intensity.2,3 Every patient’s “pain vocabulary” contains nuanced connotations: aching, pulling, burning, stinging, stabbing, or radiating, to name a few.6 Quantifying “how much it hurts” eludes visual documentation (X‐ ray, MRI) or objective physiologic measurement (heart rate, blood pressure, hormone response, or other empirical information). No matter the clinical setting or circumstance, however, adequate pain management requires precise, thorough pain assessment—an individualized approach.4,7–9 Assessing, treating, and monitoring pain is germane to every discipline—from general clinical practice through all subspecialties.10 Likewise, research assessing novel therapies and treatments pose additional challenges, particularly when changes in pain represent the primary outcome variable. The most credible expression of pain comes via each patient’s self‐report using their unique pain vocabulary.4,6,8 When cognitively and physically capable, the patient is the best source for accurately communicating the extent to which pain moderates, worsens, or varies over time.4,6,8
VAS Used to Assess Pain Intensity in Diverse Clinical Settings The European Palliative Care Research Collaborative, and scores of others charged with pain measurement, agree the most clinically relevant dimension to pain assessment, regardless of disease or condition, is pain intensity (PI).5,7 A preponderance of evidence demonstrates that the 100 mm visual analog scale (VAS) is by far the most
frequently used assessment instrument5,8,9–11 to evaluate analgesic effects of various therapies and detect minute pain changes during analgesic administration. Structurally, we find the VAS a simple tool to use by anyone cognitively capable of understanding the parameters and responding to clinician instructions. Indeed its popularity is frequently attributed to the ease and convenience of the VAS in a fast‐ paced clinical setting.4 PI may be the most convenient dimension to assess quickly, but interpreting a VAS reading is no simple matter.12 Context plays an important role when translating a VAS score into an evidence‐based treatment. One specialty treats nociceptive pain; another focuses on relieving patients suffering neuropathic pain.13 Hodgins2 and other authorities8 suggest that identical scores on a pain scale may be treated differently based on the specialty and individual patient.2 High pain scores may be termed acceptable immediately following traumatic injury, yet unacceptable if they persist over time.2,3 The underlying cause of pain (surgery vs. migraine headache), and clinical setting (acute care vs. hospice) illustrates that no “one size fits all.” Because VAS is an extremely common means of estimating and monitoring PI, it raises this conundrum: is VAS really the most effective assessment tool? Could flaws within the tool itself contaminate results? Or, might clinical interpretation of pain scores rob the VAS of consistency and reliability? We posit the tool and its
1 Rebecca D. Considine Research Institute, Akron Children’s Hospital, Akron, OH, USA 2 Division of Clinical Pharmacology and Toxicology, Department of Pediatrics, Akron Children’s Hospital, Akron, OH, USA 3 College of Medicine, Northeast Ohio Medical University (NEOMED), Rootstown, OH, USA
Submitted for publication 28 October 2013; accepted 17 December 2013. Corresponding Author: Michael D. Reed, PharmD, FCCP, FCP, Director, Rebecca D. Considine Research Institute, Akron Children’s Hospital, One Perkins Square, Akron, OH 44308, USA Email: [email protected]
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The Journal of Clinical Pharmacology / Vol 54 No 3 (2014)
Ironically, these investigators cannot reach consensus on which precise tick‐mark on the 100 mm continuum corresponds to clinically relevant “moderate pain.” 3,5,9,14 Studies differ on what is considered a moderate pain threshold, beginning with >30 mm, up to >60 and even >75 mm.14,17 Similarly, Stinson et al15 question whether a difference of 10 mm represents a meaningful change in PI. Williams et al8 report the meaning of identical tick‐marks on a scale vary by patient. One individual’s number expresses “average, everyday pain.” A second patient considers the same VAS location as “barely tolerable.”18 Several studies describe a “ceiling and floor” effect—a clustering of results around lower and higher endpoint descriptors.1,8,18 Our own recent use of the VAS19 supports the interpretive difficulties Stinson and colleagues cite.17,18 This is further supported by investigators who point out that pain is not a linear
clinical application combine to produce undependable, sometimes capricious results. Moreover, this variability and imprecision inherent in the standard VAS confounds extrapolation of findings from differing research investigations when applied to a global patient population. Ours is not an especially new or novel perspective. Authors representing diverse clinical and research domains have reported similar concerns over the decades.1,2,4,7–16
Clinical Interpretation Issues Many clinicians and investigators consider the 100 mm continuum of the VAS (Figure 1A and B) superior in capturing subtle differences (sensitivity) compared to the few discrete points of categorical pain scales that limit responses to 4, 5, 7, or 11 choices8 (Figure 2A and B).
A)) Traditional VAS Sca ale:
B) Vertic cal VAS Sca ale:
__ _______ _______ _______ _______ ______ 0
The e Worst Imag ginable Pain
100
No o Pain
Worst Pain Possible e
No Pain
C)) Typical Numeric Paiin Scale
0 1 No o Pain
2
3
4
5
D: Iowa a Pain Therrmometer Scale
6
7
8
9 10 uciating Excru P Pain
Figure 1. (A) The conventional 100 mm Visual Analog Scale with two commonly used end point descriptors. (B) Vertical VAS (note yet another high end‐point descriptor variation). (C) The 11‐point Numerical Rating Scale (NRS). Studies show this scale is less sensitive in detecting pain intensity changes over time. (D) The Iowa Pain Thermometer employs a vertical format and visual metaphor to suggest pain intensity rises or falls in a manner analogous to how a thermometer registers heat. (Used with permission of Keela Herr, PhD, RN, College of Nursing, The University of Iowa).
243
Reed and Van Nostran
phenomenon.15 For this reason, one may not assume a score of 50 is precisely two times that of 25.17,18
Unnecessary Variations Granted that at the bedside, the patient’s report of increasing or decreasing PI trend should provide data on which to base individual clinical pain management decisions. Nevertheless, the advantages of more consistent, universal VAS score comparisons in clinical and research settings would broaden this assessment tool’s accuracy and reliability. Equally important, greater consistency among VAS values enhances the scale’s comparative applicability across pain treatment study publications. Many have attempted to enhance the precision and broader applicability of the standard VAS (Figure 2). Design and formatting variables among VAS pain scale versions include: (1) anchor terminology, (2) presence/ absence of line markers, (3) interpreting the baseline and successive measures, and (4) the units of measurement and length of the scale, and (5) horizontal or vertical orientation.11 Some of these “modified VAS” instruments are shown in Figure 1C and 1D. We believe some modifications can and do enhance the value of the data derived. However, for extrapolation across differing patient populations and accounting for the tremendous heterogeneity in patient sensations and descriptions of PI, incorporating a few basic changes should result in a universally accepted VAS. One especially constructive modification would result from adopting identical and clinically universal anchoring terminology—the descriptive terms that provide user reference points. A review of published VAS tools reveals a spectrum of anchor descriptor terms. The differing, seemingly arbitrary, anchor point label verbiage interjects an important variation for patient and clinician. Universally accepted definitions or numerals to quantify PI beginning with “no pain” and escalating to “worst pain ever” (or other nomenclature) do not exist. In reality “worst pain ever” is infinite. It is always possible for a patient to experience more pain than they deemed the “worst ever” just 60 min ago.1 By forcing patients into selecting “worst pain ever” a second or third time, their response
must be interpreted as “no change” even if that person’s pain steadily increased.1 In fact, Williams quotes one study subject as saying, “having to put 100 would make me feel worse.”8 Several less finite anchor labels are already in use: “unbearable pain,” “excruciating pain,” “very intense pain,” and others. Even “no pain,” although finite, is affected by each patient’s pain threshold and subjective distinction between what they deem simply an unpleasant sensation versus clinically relevant pain.1 This lack of uniformity, precision, and consensus in the format and application of VAS within institutions, between medical practitioners, and even among two clinicians working side‐by‐side in the same department, renders relative clinical comparison extremely difficult. With the increasing demand for provision of evidence‐ based medicine, collaborative interdisciplinary care models, and trend toward comparative effectiveness research—we can, and must, do better in assessing PI.
Can We Improve the VAS and Its Clinical Application? We posit that clinicians and researchers would be better served with a universal VAS construct and more consistent interpretive practices within the context of each specialty. We believe such consistency will bring clarity to published findings and yield more clinically relevant pain assessment data for investigators and clinicians alike and, most importantly, foster more accurate, and thus, clinically relevant data extrapolation across studies for applicability to the individual patient. Our vision of a universal VAS (Figure 2) includes three minimal revisions: 1. We advocate identifying and labeling a relative mid‐point descriptor to denote “moderate pain.” In our opinion this will not significantly diminish the instrument’s ability to detect subtle PI changes. This will, however, provide a relative locale that patients and clinicians can agree upon to represent pain‐varying degrees of “moderate” pain. 2. We recommend all clinical practitioners and researchers adopt identical end point labels to
Figure 2. Depiction of the 100 mm horizontal VAS model we recommend. We propose a 100 mm VAS with generic end point descriptors and an additional mid‐point descriptor to establish an approximate area of moderate pain. Unlike high end descriptors such as “the most intense pain imaginable,” or “maximal amount of pain,” the descriptors “mild,” “moderate,” and “severe” are neutral in their connotation. Minimal visual cues delineating general mild, moderate, and severe areas directs the eye to a relative area of the scale, yet still offers patients a 100 mm range to mark a discrete point for each successive pain measurement. A uniform patient instruction might be: “Rate your pain on a scale of zero to 100. Zero is equal to no pain. Make a mark anywhere on the line to show me how much pain you have right now.”
244 enhance consistency and uniformity across disciplines and even within institutions. Revising the high end description term “worst pain ever” to a less finite descriptor will also moderate the ceiling effect. The rationale for the three descriptors we recommend appears in Figure 2. 3. The number of millimeters corresponding to a clinically relevant decrease or increase in PI should be quantified within a reasonable range and adopted as a universal clinical practice guideline (the mid‐point descriptor should facilitate this assessment). There will always be room for clinicians to adjust their interpretation of standard scores based on patient needs or mitigating circumstances. Given The Joint Commission20 mandates pain assessment for all patients and the Institute of Medicine’s Committee on Advancing Pain Research, Care, and Education21 identifies pain management as a “moral imperative,” perhaps the time is ripe for a comprehensive multicenter cross‐disciplinary study with significant power to establish consistency in how this instrument is administered and interpreted. The ultimate goal should be to accumulate sufficient evidence to support “gold standard” guidelines which are then “tweaked” to meet specific needs of each medical specialty, clinical setting, and research study design. Once accomplished, frequent and effective training in how to administer and interpret VAS scores according to the guidelines should be mandated to improve rater and interpretive consistency within and among varied clinical settings. Enhanced uniformity of pain assessments and interventions across disciplines can only benefit the science and, above all, the patients under our care. Although a substantial and time‐consuming undertaking, it could prove well worth the pain!
Declaration of Conflicting Interest The authors have no financial interests to disclose. References 1. Langley GB, Sheppeard H. Pain‐mood relationships in patients with rheumatoid arthritis. N Z Med J. 1985;98(774):138–141. 2. Hodgins MJ. Interpreting the meaning of pain severity scores. Pain Res Manag. 2002;7(4):192–198. 3. Franck LS, Bruce E. Putting pain assessment into practice: why is it so painful? Pain Res Manag. 2009;14(1):13–20.
The Journal of Clinical Pharmacology / Vol 54 No 3 (2014) 4. Younger J, McCue R, Mackey S. Pain outcomes: a brief review of instruments and techniques. Curr Pain Headache Rep. 2009; 13(1):39–43. 5. Breivik H, Borchgrevink PC, Allen SM, et al. The visual analogue pain intensity scale: what is moderate pain in millimetres? Pain. 1997;72(1–2):95–97. 6. Melzack R. The McGill pain questionnaire: major properties and scoring methods. Pain. 1975 1(3):277–299. 7. Hjermstad MJ, Fayers PM, Haugen DF, et al. “What progress have we made?” PowerPoint presented at The Norwegian University of Science and Technology (NTNU) Sixth Framework Programme, 2009. 8. Williams A, Davies H, Chadury Y. Simple pain rating scales hide complex idiosyncratic meanings. Pain. 2000;85:457–463. 9. Hirschfeld G, Zernikow B. Cut points for mild, moderate, and severe pain on the VAS for children and adolescents: what can be learned from 10 million ANOVAs? Pain. 2013;154(12):2626– 2632. 10. Schechter NL. From the Ouchless place to comfort central: the evolution of a concept. Pediatrics. 2008;122(suppl 3):S154– S160. 11. Hjermstad MJ, Fayers PM, Caraceni A, et al. Studies comparing numerical rating scales, verbal rating scales, and visual analogue scales for assessment of pain intensity in adults: a systematic literature review. J Pain Symptom Manage. 2011;41(6):1073– 1093. 12. Williamson A, Hoggart B. Pain: a review of three commonly used pain rating scales. J Clin Nurs. 2005;14(7):798–804. 13. Lund I, Lundeberg T, Sandberg L, Budh CN, Kowalski J, Svensson E. Lack of interchangeability between visual analogue and verbal rating pain scales: a cross sectional description of pain etiology groups. BMC Med Res Methodol. 2005;4(5):31. 14. Collins SL, Moore RA, McQuay HJ. The visual analogue pain intensity scale: what is moderate pain in millimetres? Pain. 1997;72(1–2):95–97. 15. Stinson JN, Kavanagh T, Yamada J, Gill N, Stevens B. Systematic review of the psychometric properties, interpretability and feasibility of self‐report pain intensity measures for use in clinical trials in children and adolescents. Pain. 2006;125(1–2):143–157. 16. McQuay HJ, Derry S, Eccleston C, Wiffen PJ, Moore RA. Evidence for analgesic effect in acute pain—50 years on. Pain. 2012; 153(7):1364–1367. 17. Hirschfeld G, Zernikow B. Variability of “optimal” cut points for mild, moderate, and severe pain: neglected problems when comparing groups. Pain. 2013;154(1):154–159. 18. Badalamente M, Coffelt L, Elfar J, et al. Selection of pain measurement tools. Nurs Stand. 2003;18(13):33–39. 19. Depue K, Christopher NC, Raed M, Forbes ML, Besunder J, Reed MD. Efficacy of intravenous lidocaine to reduce pain and distress associated with propofol infusion in pediatric patients during procedural sedation. Pediatr Emerg Care. 2013;29(1):13–16. 20. Phillips DM, JCAHO pain management standards are unveiled. Joint Commission on Accreditation of Healthcare Organizations. JAMA. 2000;284(4):428–429. 21. IOM (Institute of Medicine). 2011. Relieving Pain in America: A Blueprint for Transforming Prevention, Care, Education, and Research. Washington, DC: The National Academies Press.
Assessing Pain Intensity With the Visual Analog Scale: A Plea for Uniformity
The Journal of Clinical Pharmacology 54(3) 241–244 © 2014, The American College of Clinical Pharmacology DOI: 10.1002/jcph.250
Michael D. Reed, PharmD, FCCP, FCP1,2,3 and William Van Nostran, BS1 Keywords Visual analogue scale (VAS), pain scale, VAS validity, pain assessment
“Those who do not feel pain seldom think that it is felt.” Dr. Samuel Johnson (circa 1750)
The sensation of pain is undeniably subjective. Personality, recollections of painful events, emotional state, age, culture, context, and other factors influence an individual’s responses to, and description of, pain.1–5 Linguistically, the word “pain” encompasses multidimensional attributes well beyond a single sensation varying only in intensity.2,3 Every patient’s “pain vocabulary” contains nuanced connotations: aching, pulling, burning, stinging, stabbing, or radiating, to name a few.6 Quantifying “how much it hurts” eludes visual documentation (X‐ ray, MRI) or objective physiologic measurement (heart rate, blood pressure, hormone response, or other empirical information). No matter the clinical setting or circumstance, however, adequate pain management requires precise, thorough pain assessment—an individualized approach.4,7–9 Assessing, treating, and monitoring pain is germane to every discipline—from general clinical practice through all subspecialties.10 Likewise, research assessing novel therapies and treatments pose additional challenges, particularly when changes in pain represent the primary outcome variable. The most credible expression of pain comes via each patient’s self‐report using their unique pain vocabulary.4,6,8 When cognitively and physically capable, the patient is the best source for accurately communicating the extent to which pain moderates, worsens, or varies over time.4,6,8
VAS Used to Assess Pain Intensity in Diverse Clinical Settings The European Palliative Care Research Collaborative, and scores of others charged with pain measurement, agree the most clinically relevant dimension to pain assessment, regardless of disease or condition, is pain intensity (PI).5,7 A preponderance of evidence demonstrates that the 100 mm visual analog scale (VAS) is by far the most
frequently used assessment instrument5,8,9–11 to evaluate analgesic effects of various therapies and detect minute pain changes during analgesic administration. Structurally, we find the VAS a simple tool to use by anyone cognitively capable of understanding the parameters and responding to clinician instructions. Indeed its popularity is frequently attributed to the ease and convenience of the VAS in a fast‐ paced clinical setting.4 PI may be the most convenient dimension to assess quickly, but interpreting a VAS reading is no simple matter.12 Context plays an important role when translating a VAS score into an evidence‐based treatment. One specialty treats nociceptive pain; another focuses on relieving patients suffering neuropathic pain.13 Hodgins2 and other authorities8 suggest that identical scores on a pain scale may be treated differently based on the specialty and individual patient.2 High pain scores may be termed acceptable immediately following traumatic injury, yet unacceptable if they persist over time.2,3 The underlying cause of pain (surgery vs. migraine headache), and clinical setting (acute care vs. hospice) illustrates that no “one size fits all.” Because VAS is an extremely common means of estimating and monitoring PI, it raises this conundrum: is VAS really the most effective assessment tool? Could flaws within the tool itself contaminate results? Or, might clinical interpretation of pain scores rob the VAS of consistency and reliability? We posit the tool and its
1 Rebecca D. Considine Research Institute, Akron Children’s Hospital, Akron, OH, USA 2 Division of Clinical Pharmacology and Toxicology, Department of Pediatrics, Akron Children’s Hospital, Akron, OH, USA 3 College of Medicine, Northeast Ohio Medical University (NEOMED), Rootstown, OH, USA
Submitted for publication 28 October 2013; accepted 17 December 2013. Corresponding Author: Michael D. Reed, PharmD, FCCP, FCP, Director, Rebecca D. Considine Research Institute, Akron Children’s Hospital, One Perkins Square, Akron, OH 44308, USA Email: [email protected]
242
The Journal of Clinical Pharmacology / Vol 54 No 3 (2014)
Ironically, these investigators cannot reach consensus on which precise tick‐mark on the 100 mm continuum corresponds to clinically relevant “moderate pain.” 3,5,9,14 Studies differ on what is considered a moderate pain threshold, beginning with >30 mm, up to >60 and even >75 mm.14,17 Similarly, Stinson et al15 question whether a difference of 10 mm represents a meaningful change in PI. Williams et al8 report the meaning of identical tick‐marks on a scale vary by patient. One individual’s number expresses “average, everyday pain.” A second patient considers the same VAS location as “barely tolerable.”18 Several studies describe a “ceiling and floor” effect—a clustering of results around lower and higher endpoint descriptors.1,8,18 Our own recent use of the VAS19 supports the interpretive difficulties Stinson and colleagues cite.17,18 This is further supported by investigators who point out that pain is not a linear
clinical application combine to produce undependable, sometimes capricious results. Moreover, this variability and imprecision inherent in the standard VAS confounds extrapolation of findings from differing research investigations when applied to a global patient population. Ours is not an especially new or novel perspective. Authors representing diverse clinical and research domains have reported similar concerns over the decades.1,2,4,7–16
Clinical Interpretation Issues Many clinicians and investigators consider the 100 mm continuum of the VAS (Figure 1A and B) superior in capturing subtle differences (sensitivity) compared to the few discrete points of categorical pain scales that limit responses to 4, 5, 7, or 11 choices8 (Figure 2A and B).
A)) Traditional VAS Sca ale:
B) Vertic cal VAS Sca ale:
__ _______ _______ _______ _______ ______ 0
The e Worst Imag ginable Pain
100
No o Pain
Worst Pain Possible e
No Pain
C)) Typical Numeric Paiin Scale
0 1 No o Pain
2
3
4
5
D: Iowa a Pain Therrmometer Scale
6
7
8
9 10 uciating Excru P Pain
Figure 1. (A) The conventional 100 mm Visual Analog Scale with two commonly used end point descriptors. (B) Vertical VAS (note yet another high end‐point descriptor variation). (C) The 11‐point Numerical Rating Scale (NRS). Studies show this scale is less sensitive in detecting pain intensity changes over time. (D) The Iowa Pain Thermometer employs a vertical format and visual metaphor to suggest pain intensity rises or falls in a manner analogous to how a thermometer registers heat. (Used with permission of Keela Herr, PhD, RN, College of Nursing, The University of Iowa).
243
Reed and Van Nostran
phenomenon.15 For this reason, one may not assume a score of 50 is precisely two times that of 25.17,18
Unnecessary Variations Granted that at the bedside, the patient’s report of increasing or decreasing PI trend should provide data on which to base individual clinical pain management decisions. Nevertheless, the advantages of more consistent, universal VAS score comparisons in clinical and research settings would broaden this assessment tool’s accuracy and reliability. Equally important, greater consistency among VAS values enhances the scale’s comparative applicability across pain treatment study publications. Many have attempted to enhance the precision and broader applicability of the standard VAS (Figure 2). Design and formatting variables among VAS pain scale versions include: (1) anchor terminology, (2) presence/ absence of line markers, (3) interpreting the baseline and successive measures, and (4) the units of measurement and length of the scale, and (5) horizontal or vertical orientation.11 Some of these “modified VAS” instruments are shown in Figure 1C and 1D. We believe some modifications can and do enhance the value of the data derived. However, for extrapolation across differing patient populations and accounting for the tremendous heterogeneity in patient sensations and descriptions of PI, incorporating a few basic changes should result in a universally accepted VAS. One especially constructive modification would result from adopting identical and clinically universal anchoring terminology—the descriptive terms that provide user reference points. A review of published VAS tools reveals a spectrum of anchor descriptor terms. The differing, seemingly arbitrary, anchor point label verbiage interjects an important variation for patient and clinician. Universally accepted definitions or numerals to quantify PI beginning with “no pain” and escalating to “worst pain ever” (or other nomenclature) do not exist. In reality “worst pain ever” is infinite. It is always possible for a patient to experience more pain than they deemed the “worst ever” just 60 min ago.1 By forcing patients into selecting “worst pain ever” a second or third time, their response
must be interpreted as “no change” even if that person’s pain steadily increased.1 In fact, Williams quotes one study subject as saying, “having to put 100 would make me feel worse.”8 Several less finite anchor labels are already in use: “unbearable pain,” “excruciating pain,” “very intense pain,” and others. Even “no pain,” although finite, is affected by each patient’s pain threshold and subjective distinction between what they deem simply an unpleasant sensation versus clinically relevant pain.1 This lack of uniformity, precision, and consensus in the format and application of VAS within institutions, between medical practitioners, and even among two clinicians working side‐by‐side in the same department, renders relative clinical comparison extremely difficult. With the increasing demand for provision of evidence‐ based medicine, collaborative interdisciplinary care models, and trend toward comparative effectiveness research—we can, and must, do better in assessing PI.
Can We Improve the VAS and Its Clinical Application? We posit that clinicians and researchers would be better served with a universal VAS construct and more consistent interpretive practices within the context of each specialty. We believe such consistency will bring clarity to published findings and yield more clinically relevant pain assessment data for investigators and clinicians alike and, most importantly, foster more accurate, and thus, clinically relevant data extrapolation across studies for applicability to the individual patient. Our vision of a universal VAS (Figure 2) includes three minimal revisions: 1. We advocate identifying and labeling a relative mid‐point descriptor to denote “moderate pain.” In our opinion this will not significantly diminish the instrument’s ability to detect subtle PI changes. This will, however, provide a relative locale that patients and clinicians can agree upon to represent pain‐varying degrees of “moderate” pain. 2. We recommend all clinical practitioners and researchers adopt identical end point labels to
Figure 2. Depiction of the 100 mm horizontal VAS model we recommend. We propose a 100 mm VAS with generic end point descriptors and an additional mid‐point descriptor to establish an approximate area of moderate pain. Unlike high end descriptors such as “the most intense pain imaginable,” or “maximal amount of pain,” the descriptors “mild,” “moderate,” and “severe” are neutral in their connotation. Minimal visual cues delineating general mild, moderate, and severe areas directs the eye to a relative area of the scale, yet still offers patients a 100 mm range to mark a discrete point for each successive pain measurement. A uniform patient instruction might be: “Rate your pain on a scale of zero to 100. Zero is equal to no pain. Make a mark anywhere on the line to show me how much pain you have right now.”
244 enhance consistency and uniformity across disciplines and even within institutions. Revising the high end description term “worst pain ever” to a less finite descriptor will also moderate the ceiling effect. The rationale for the three descriptors we recommend appears in Figure 2. 3. The number of millimeters corresponding to a clinically relevant decrease or increase in PI should be quantified within a reasonable range and adopted as a universal clinical practice guideline (the mid‐point descriptor should facilitate this assessment). There will always be room for clinicians to adjust their interpretation of standard scores based on patient needs or mitigating circumstances. Given The Joint Commission20 mandates pain assessment for all patients and the Institute of Medicine’s Committee on Advancing Pain Research, Care, and Education21 identifies pain management as a “moral imperative,” perhaps the time is ripe for a comprehensive multicenter cross‐disciplinary study with significant power to establish consistency in how this instrument is administered and interpreted. The ultimate goal should be to accumulate sufficient evidence to support “gold standard” guidelines which are then “tweaked” to meet specific needs of each medical specialty, clinical setting, and research study design. Once accomplished, frequent and effective training in how to administer and interpret VAS scores according to the guidelines should be mandated to improve rater and interpretive consistency within and among varied clinical settings. Enhanced uniformity of pain assessments and interventions across disciplines can only benefit the science and, above all, the patients under our care. Although a substantial and time‐consuming undertaking, it could prove well worth the pain!
Declaration of Conflicting Interest The authors have no financial interests to disclose. References 1. Langley GB, Sheppeard H. Pain‐mood relationships in patients with rheumatoid arthritis. N Z Med J. 1985;98(774):138–141. 2. Hodgins MJ. Interpreting the meaning of pain severity scores. Pain Res Manag. 2002;7(4):192–198. 3. Franck LS, Bruce E. Putting pain assessment into practice: why is it so painful? Pain Res Manag. 2009;14(1):13–20.
The Journal of Clinical Pharmacology / Vol 54 No 3 (2014) 4. Younger J, McCue R, Mackey S. Pain outcomes: a brief review of instruments and techniques. Curr Pain Headache Rep. 2009; 13(1):39–43. 5. Breivik H, Borchgrevink PC, Allen SM, et al. The visual analogue pain intensity scale: what is moderate pain in millimetres? Pain. 1997;72(1–2):95–97. 6. Melzack R. The McGill pain questionnaire: major properties and scoring methods. Pain. 1975 1(3):277–299. 7. Hjermstad MJ, Fayers PM, Haugen DF, et al. “What progress have we made?” PowerPoint presented at The Norwegian University of Science and Technology (NTNU) Sixth Framework Programme, 2009. 8. Williams A, Davies H, Chadury Y. Simple pain rating scales hide complex idiosyncratic meanings. Pain. 2000;85:457–463. 9. Hirschfeld G, Zernikow B. Cut points for mild, moderate, and severe pain on the VAS for children and adolescents: what can be learned from 10 million ANOVAs? Pain. 2013;154(12):2626– 2632. 10. Schechter NL. From the Ouchless place to comfort central: the evolution of a concept. Pediatrics. 2008;122(suppl 3):S154– S160. 11. Hjermstad MJ, Fayers PM, Caraceni A, et al. Studies comparing numerical rating scales, verbal rating scales, and visual analogue scales for assessment of pain intensity in adults: a systematic literature review. J Pain Symptom Manage. 2011;41(6):1073– 1093. 12. Williamson A, Hoggart B. Pain: a review of three commonly used pain rating scales. J Clin Nurs. 2005;14(7):798–804. 13. Lund I, Lundeberg T, Sandberg L, Budh CN, Kowalski J, Svensson E. Lack of interchangeability between visual analogue and verbal rating pain scales: a cross sectional description of pain etiology groups. BMC Med Res Methodol. 2005;4(5):31. 14. Collins SL, Moore RA, McQuay HJ. The visual analogue pain intensity scale: what is moderate pain in millimetres? Pain. 1997;72(1–2):95–97. 15. Stinson JN, Kavanagh T, Yamada J, Gill N, Stevens B. Systematic review of the psychometric properties, interpretability and feasibility of self‐report pain intensity measures for use in clinical trials in children and adolescents. Pain. 2006;125(1–2):143–157. 16. McQuay HJ, Derry S, Eccleston C, Wiffen PJ, Moore RA. Evidence for analgesic effect in acute pain—50 years on. Pain. 2012; 153(7):1364–1367. 17. Hirschfeld G, Zernikow B. Variability of “optimal” cut points for mild, moderate, and severe pain: neglected problems when comparing groups. Pain. 2013;154(1):154–159. 18. Badalamente M, Coffelt L, Elfar J, et al. Selection of pain measurement tools. Nurs Stand. 2003;18(13):33–39. 19. Depue K, Christopher NC, Raed M, Forbes ML, Besunder J, Reed MD. Efficacy of intravenous lidocaine to reduce pain and distress associated with propofol infusion in pediatric patients during procedural sedation. Pediatr Emerg Care. 2013;29(1):13–16. 20. Phillips DM, JCAHO pain management standards are unveiled. Joint Commission on Accreditation of Healthcare Organizations. JAMA. 2000;284(4):428–429. 21. IOM (Institute of Medicine). 2011. Relieving Pain in America: A Blueprint for Transforming Prevention, Care, Education, and Research. Washington, DC: The National Academies Press.
