SAN DIEGO – Of the many scales at a clinician’s disposal to measure acute pain, the three most commonly used are the Numerical Rating Scale, the Verbal Rating Scale, and the Visual Analog Scale, Dr. Jeffrey A. Stone said at the annual meeting of the Society of Neurointerventional Surgery.
"All of these scales have been shown to be statistically reliable and valid," said Dr. Stone, associate professor of neurointerventional surgery in the radiology department at the Mayo Clinic, Jacksonville, Fla. In his clinical experience, most patients prefer the Numerical Rating Scale (NRS) and the Verbal Rating Scale (VRS) because they are easy to use. "The other advantage is that these can be conducted by telephone or electronic diaries," he said.
The NRS is a familiar and commonly used 0-10 scale, where 0 = no pain, 1-3 = mild pain, 4-6 = moderate pain, and 7-10 = severe pain. "If patients tell you, ‘I’m a 5 out of 10,’ that can be difficult to gauge, particularly in the elderly," Dr. Stone said. "The VRS, a four-scale system ranging from no pain up to severe pain, is somewhat simpler and correlates well with the NRS."
With the Visual Analog Scale, patients are asked to make a vertical slash on a 100-mm line to denote their level of pain. "I use this scale a lot, but it can be cumbersome, particularly with follow-up," he said.
Factors to consider in the backdrop of pain intensity include rescue analgesics, which may be prescribed by other physicians for sleep or anxiety, or may be used to prevent pain from increased activity or to treat unrelated pain. "Another factor is concomitant pain treatments, such as acupuncture and chiropractic treatments," Dr. Stone said. "In addition, patients enrolled in the placebo group of a clinical trial are generally expected to have more pain medication use compared with those in an efficacious treatment group."
Other distinct components of pain include pain sensation and pain affect. Pain sensation "is the quality of the pain, such as burning, throbbing, or sharp pain versus dull pain," Dr. Stone said. "There are also temporal aspects to pain, such as variability of intensity over time; time to onset of meaningful pain relief; durability of pain relief; and the frequency, duration, and intensity of pain episodes. Pain affect is the mental distress caused by the pain."
Global pain assessments for pain sensation and pain affect include a modification of the McGill Pain Questionnaire (MPQ), known as the short-form MPQ, and the Brief Pain Inventory (BPI), which was adapted from the Wisconsin Brief Pain Questionnaire. The short-form MPQ contains 15 sensory and affective descriptors, while the BPI "does a much better job measuring the temporal aspect of pain and is often used in conjunction with the short-form MPQ," Dr. Stone said.
Two other core pain outcome domains are physical function and emotional function. Effective outcome measures for these domains include the Oswestry Disability Index (ODI), the Short Form-36 (SF-36), the Roland-Morris Disability Questionnaire (RMQ) and the Pain Disability Index (PDI).
The ODI, a 10-item questionnaire, "has been used in many pain trials," he said. "It looks at pain intensity but also other things such as lifting, the ability to walk, social life, sexual activity, and sleep cycle. It is a very accurate way to look at a patient’s global disability from pain."
He described the SF-36 as "a little bit more cumbersome for patients to complete" in measuring physical and emotional function. This tool provides an eight-scale profile of functional health and well-being scores, as well as a psychometric-based physical and mental health summary.
The 24-item RMQ consists of yes/no questions intended to measure self-perceived disability, while the 7-question PDI measures pain interference in physical and psychosocial role performance.
In a later interview, Dr. Stone said that the NRS, VRS, and VAS instruments can be used in hospitalized patients. Outcome measures such as the ODI and the RMQ "would not be very useful, as they ask many functional questions such as sex life [and] activity level, which would not be applicable to a hospitalized patient."
Dr. Stone said that he had no relevant financial disclosures to make.