Effectively Managing Chronic Pain

National Harbor, Maryland—When treating patients who suffer from chronic pain, clinicians must consider biologic, psychological, and social factors that contribute to the condition. In addition, according to presenters at the AAPM meeting, successful pain management should take into consideration the fact that pain perception involves sensory, affective, and cognitive elements. These topics were discussed during a satellite symposium titled Comprehensive Chronic Pain Management: Improving Physical and Psychological Function. Steven Stanos, DO, medical director at the Rehabilitation Institute of Chicago’s Center for Pain Management, cited surveys of pain medicine physicians, internal medicine residents, and interns that indicated medical professionals are unaware of and lack training with chronic pain management. Dr. Stanos said that a comprehensive treatment program has several goals: optimizing pain control; improving functional abilities, physical and psychological well-being, and quality of life; and minimizing adverse events and outcomes. Several organizations have guidelines for treating pain, including the AAPM/American Pain Society’s Opioid Therapy in Chronic Noncancer Pain; the American Geriatrics Society’s Pharmacologic Management of Persistent Pain in the Elderly; the Institute for Clinical Systems Improvement’s Chronic Pain Assessment and Management; and the American Society of Anesthesiologists’s Chronic Pain Management. The guidelines contain similar recommendations. They suggest clinicians utilize a biopsychosocial approach in assessing and managing pain, use pharmacologic and nonpharmacologic methods, closely evaluate patients when prescribing and monitoring opioids, and use agents with different mechanisms of action (MOAs) to increase efficacy and minimize side effects. “The key is, are all those guidelines really helping us improve patient care?” Dr. Stanos asked. David A. Williams, PhD, professor of anesthesiology and medicine at the University of Michigan, Ann Arbor, defined pain as an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage. Although most research is focused on the sensory aspects of pain, Dr. Williams said that there should be more research on the affective aspects. “Affect is an integral part of the pain experience,” he added. Pain is typically classified based on the time from onset, location on the body, and suspected etiology. During his discussion, Dr. Williams spoke about classifying pain based on its mechanism. Nociceptive pain is caused by physiologic stimuli such as a pin prick, noxious heat or cold, or a chemical injury or clinically relevant stimuli such as osteoarthritis, angina, or ischemic claudication. Dr. Williams said nociceptive pain is receptive to nonsteroidal antiinflammatory drugs (NSAIDs) and opioids. An example of nociceptive pain is acute pain. According to Dr. Williams, inflammatory pain is caused by mechanical damage or peripheral inflammation such as tissue trauma or joint inflammation and is responsive to NSAIDs, opioids, and corrective procedures. He classified some cancer pain and pain associated with rheumatoid arthritis as examples of inflammatory pain. Neuropathic pain is caused by peripheral or central nerve damage or entrapment and is responsive to peripheral analgesics, central analgesics, antidepressants, anticonvulsants, and surgery. Dr. Williams said peripheral neuropathic pain is found in trauma, infections, compression, and diabetes, whereas central neuropathic pain is found in multiple sclerosis, stroke, HIV, and myelopathy. Central pain is caused by augmented central nervous pain system pain processing but is not associated with tissue damage or inflammation. It is responsive to central analgesics, antidepressants, and anticonvulsants but is unresponsive to NSAIDs, opioids, or surgery, according to Dr. Williams. Examples of central pain include fibromyalgia, irritable bowel yndrome, temporomandibular disorder, and interstitial cystitis. Dr. Williams also discussed if individuals can be predisposed to develop chronic pain. Dr. Williams said that although there is no single gene associated with or responsible for chronic pain, there are 2 components that may predict chronic pain: high psychological distress such as mood disorder, depression, or anxiety; or a high state of pain amplification such as that found in tissue injuries, high blood pressure, or impaired pain regulatory systems. Dr. Williams said patients do not need to have depression or an anxiety disorder to negatively influence their pain perception, but research has indicated an association between anxiety and pain. He cited studies showing anxiety is the strongest predictor of pain level after operations and that anxiety can lower pain threshold and cause a heightened awareness of pain. One of the studies indicated that patients who were anxious at the time of surgery had greater pain and fatigue 3 months after surgery compared with patients who were not anxious. Bill McCarberg, MD, adjunct assistant clinical professor at the University of California at San Diego, and founder of the Chronic Pain Management program at Kaiser Permanente, followed by noting that pain is based on a person’s subjective perception. He said biologic changes, psychological status, and sociocultural context all play a role in how patients perceive and respond to pain. Dr. McCarberg cited a report from the Institute for Clinical Systems Improvement that recommended clinicians begin assessing pain by examining a patient’s history with pain and physical condition as well as using pain and functional tools. They should then determine the biologic mechanisms of pain: neuropathic pain, muscle pain, inflammatory pain, or mechanical/compressive pain. If no correctable cause for the pain can be found, clinicians should assess other factors such as work and disability issues, psychological and spiritual assessment, and contributing factors and barriers. Dr. McCarberg highlighted several types of medications used to treat chronic pain. In the adjuvants category, there are benzodiazepines, skeletal muscle relaxants, antidepressants, and anticonvulsants. There are also NSAIDs, acetaminophen, and opioids such as hydromorphone, fentanyl, oxycodone, hydrocodone, buprenorphine, tramadol, and tapentadol. In addition, the US Food and Drug Administration recently approved transdermal buprenorphine and duloxetine to treat chronic pain. When choosing what treatment to use, Dr. Stanos said clinicians should consider the pain severity, functional impact, pain mechanism, MOA, and biopsychosocial factors as well as assess the risks and benefits associated with the therapy. Because all treatments have side effects, Dr. Stanos suggested using agents that have different MOAs and address different biopsychosocial factors. He said studies have estimated that as many as 50% of patients with chronic pain have aberrant drug-related behaviors, drug abuse, or drug misuse. Nonpharmacologic treatment is also important, according to Dr. Stanos. He said that physical therapy and exercise could improve function and often results in decreased pain. Cognitive-behavioral therapy (CBT) is another option. In a randomized controlled trial cited by Dr. Stanos, CBT was as effective as spinal fusion in improving disability scores in 64 patients who had chronic lower back pain and disc degeneration.