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Abstract & Commentary
Synopsis: The common and increasing practice of opioid treatment for chronic pain is reviewed. Randomized trials support this therapy, however the risk benefit decision is complicated by new evidence of hazards making this practice more difficult.
Source: Ballantyne JC, Mao J. N Engl J Med. 2003;349:1043-1953.
Early adoption of opioid therapy for chronic pain not associated with terminal disease was largely based on uncontrolled case series and anecdote. Fifteen of 16 randomized trials have since shown significant analgesia in a variety of chronic pain conditions including neuropathic pain. Functional improvement was also shown but was less impressive. Opioid doses used varied but were moderate (up to 180 mg of morphine or a morphine equivalent per day) and were used for less than 32 weeks. Important unanswered questions remain: are opioids effective over longer periods—perhaps many years; and does the dose have an effect on efficacy and safety? These questions are particularly vital since current practice suggests ever increasing doses until analgesia is reached or side effects limit further escalations.
Ballantyne and colleagues present animal and human data on opioid induced abnormal pain sensitivity. Distinct from opioid tolerance, this hyperalgesia may suggest a ceiling effect to therapy. Opioid effects on the hypothalamic-pituitary-gonadal axis, immune modulation, and other previous little known effects are also discussed. Trial data, standard doses of commonly used opioids, and a protocol for opioid therapy are also presented.
Comment by William McCarberg, MD, FABPM
Despite efforts from the government, regulatory agencies, pain societies, and the public, pain is still inexplicably undertreated even in patients dying of cancer. Reluctance to use opioid therapy is based on many factors from provider bias, patient fears to regulatory oversight from the very agencies that lobby for more aggressive pain treatment. Caught in the middle is the clinician who is committed to palliate unnecessary pain. This review article puts a new twist on this controversial subject. Gone are the days that all pain patients deserved an opioid trial based on pain levels alone. Risks were under represented based on provider experience and a well-meaning desire to provide meaningful pain relief. Prescription opioid abuse is a real problem and must be handled. But as the pendulum of pain treatment swings toward balance, we must not forget that 15 of 16 clinical trials showed significant analgesia and uncontrolled pain remains a national tragedy.
Dr. McCarberg is Physician-In-Charge, Chronic Pain Program, Kaiser Permanente, San Diego, California.