Source: Blumstein HA, et al. Visual analogue pain scores do not define desire for analgesia in patients with acute pain. Acad Emerg Med 2003;10:211-214.
The objective of this study was to investigate the ability of the visual analog scale (VAS) to differentiate between patients with acute painful conditions desiring pain medication and those not desiring medication. In this prospective, observational study of a convenience sample of adult patients who presented to an academic emergency department (ED) with acute pain, patients with acute exacerbations of chronic pain were excluded along with other reasonable exclusion criteria. Subjects were asked by research assistants to complete a VAS. "No pain at all," on the far left of the VAS, was separated by a 100 mm line (without markings) from "Severe, uncontrolled pain" on the far right. Patients then were asked to respond "yes" or "no" to the question: "Do you need pain medication?"
A total of 104 subjects participated in this study. Patients requesting pain medication (n = 64) had a mean VAS score of 66 (SD ± 23.1). The mean score for those not requesting medication (n = 40) was 45 (SD ± 29.4). The difference between the means was 21 (95% CI, 10.3-31.3). The area under the receiving operator characteristic curve for the VAS was 0.72 (95% CI, 0.61-0.82).
Commentary by Stephanie B. Abbuhl, MD, FACEP
This deceptively simple study delivers an important concept to the clinical world of pain management. Despite some methodologic flaws, the results indicate that the VAS cannot adequately discriminate between patients who do and do not want analgesia for their pain. Although there is a statistical difference in the VAS scores of the two patient groups, there is considerable overlap of the scores and no single cutoff point can adequately predict a given patient’s desire for medication. Therefore, the routine clinical role of pain measurement tools like the VAS is called into question.
This does not mean that the VAS is not a reliable and effective tool for measuring pain, especially in research settings where measuring a minimum clinically significant difference in pain, regardless of need for analgesia, is important. In the ED, however, the major goal of pain assessment is to determine the desire for pain medication, given that analgesia is our single key intervention. It is true that other interventions, such as reassurance, music, comfort measures, and acupressure, significantly may affect acute pain. However, until we have more data on how these kinds of interventions might be of practical use, we are left needing a tool that identifies pain and primarily measures the need for pain medication. Until further research clarifies the clinical role of the VAS, it may be that the most practical and efficient pain assessment tool in the ED is simply to ask patients initially if they want pain medication and, when reassessing the patients, inquire about the need for more pain medication.
Dr. Abbuhl, Medical Director, Department of Emergency Medicine, The Hospital of the University of Pennsylvania; Associate Professor of Emergency Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA, is on the Editorial Board of Emergency Medicine Alert.
The objective of this study was to investigate the ability of the visual analog scale to differentiate between patients with acute painful conditions desiring pain medication and those not desiring medication.
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