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Subhash Jain, MD, Department Editor
Department editor's note: When is a pain problem a candidate for opioid therapy? What types of pain respond to opioids? Can the long-term use of opioids for chronic pain lead to needless complications? These and related questions dog pain clinicians as they manage patients who have chronic pain but not life-threatening disease. Using opioids for noncancer pain is a long-standing controversial issue; however, during the last two decades our knowledge of the sites and mechanisms of pain has increased dramatically. The following pair of articles present a point-counterpoint perspective on the issue of using opioids for the control of chronic noncancer pain.
Mark Stillman, MD
Several years ago, in the pages of APS Bulletin, Turk and Brody (1992) published the results of a survey on the position APS physicians take regarding chronic opioid therapy for chronic noncancer pain. The findings should be no surprise to the readers: (a) 83% of respondents maintained patients on chronic opioid therapy; (b) their goals were, first, analgesia, and second, improved function; (c) respondents believed opioids were underused and addiction overemphasized; and (d) a significant minority of clinicians (40%) regarded actual or perceived regulatory scrutiny as a concern.
When Turk, Brody, and Okifuji (1994) turned their attention to diverse groups of U.S. physicians who did not identify themselves as members of the American Pain Society, the frequency of chronic opioid prescribing was decidedly lower. However, similar concerns loomed in these physicians' collective conscience: concerns about regulatory scrutiny; fears of inducing addiction, tolerance, and physical dependence; and worries that prescribing these drugs would not lead to an improvement in function.
An educated look at this issue produces a dearth of scientific studies on which to base practice guidelines, in contrast to the wealth of clinical experience gleaned by practitioners over the past two decades. In the accompanying article, Stein points out that there are no extant prospective, randomized, placebo-controlled studies of chronic noncancer pain that demonstrate opioid efficacy in the form of either analgesia, partial or complete, or improvement in patients' physical, social, or psychological functioning (Stein, 1996). Yet, the fact is, no studies exist to the contrary that prove opioid analgesics' detriment. In effect, no comprehensive study of chronic opioid use for chronic noncancer pain exists that would satisfy the purist in any of us (scientists)! Clearly such a prospective study would be difficult to conduct in a blinded manner, considering the easily identifiable side effects of opioid medications.
In spite of an ever-changing political climate and the arguments cited above, several states have recently succeeded in passing intractable pain acts, which protect from prosecution clinicians who prescribe chronic opioids to patients with chronic noncancer pain (Joranson, 1995). Moreover, a variety of agencies are preparing consensus statements and clinical practice guidelines in support of opioid use for the treatment of chronic noncancer pain, intractable or not.
For those of us who not only treat patients with chronic pain, but also educate practicing clinicians and physicians in training, there is solace and strength in the International Association for the Study of Pain definition of pain (Merskey, 1979). For in a few words, this explanation emphasizes that pain is not only a neurophysiological phenomenon that accompanies physical injury, but also a perception of potential injury and a subjective emotional experience invested in the element we call suffering. Dissecting these many facets of a patient's clinical pain history can be as daunting an endeavor as creating an effective treatment plan, considering the enormously complex psychosocial environment in which this pain develops.
Whether a member of an established multidisciplinary team or a solo practitioner, the conscientious pain physician attempts to treat the patient's multifaceted clinical condition with a tailored, sometimes multifaceted, approach-and opioids frequently assume a role during the effort. Portenoy (1994) pointed out that while there is a population of patients who deteriorate from the introduction of opioids, there is also a population of patients in clinical practice who benefit not only from pain relief, but also from increased socioeconomic and physical functioning and improved psychological outlook. The issue is how to differentiate the two populations in daily practice. Portenoy proposed the evaluation of three separate clinical parameters, in hopes of creating the appropriate litmus test: (a) the variability of opioid responsiveness; (b) the durability of analgesic response, vis--vis the development of tolerance, and (c) the appropriateness of therapy in the context of larger treatment goals. The first parameter has garnered the most interest in the pain literature.
A number of researchers have considered the issue of opioid responsiveness (Arner & Meyerson, 1988; Bruera, Macmillan, Hanson, & MacDonald, 1989; Cherny et al., 1994; Kupers, Konings, Adriaensen, & Gybels, 1991; Portenoy, Foley, & Inturrisi, 1990; Rowbotham, Reisner-Keller, & Fields, 1991). Bruera's group reported the ability to clinically predict a less adequate analgesic response to opioid analgesics (a) when the pain is neuropathic, as opposed to nociceptive; (b) when the pain is incident in nature; (c) when the patient exhibits impaired cognition; (d) when the patient shows high levels of psychosocial distress; and (e) when there is an ongoing use of large doses of opioids, with (f) a need for rapid dose escalation. Others have suggested that a neuropathic pain mechanism reduces opioid analgesic efficacy (Arner & Meyerson; Kupers et al.). This point has been contested by other researchers demonstrating a favorable response of neuropathic pain to opioids, although sometimes in higher doses (McQuay et al., 1992; Portenoy et al.; Rowbotham et al.; Zenz, Strumpf, & Tryba, 1992).
In a prospective, nonrandomized, noncontrolled study of 100 chronic pain patients with nociceptive, neuropathic, or mixed pain disorders, Zenz et al. (1992) demonstrated not only an analgesic response but also a functional improvement in the neuropathic group treated with opioids on a time-contingent basis. Contrary to currently held belief, neuropathic pain, as a whole, required lower doses of opioids than nonneuropathic pain states. They noted no instances of addiction, and around-the-clock dosing obviated iatrogenic drug-seeking behavior (pseudoaddiction). Rowbotham et al. (1991) likewise demonstrated opioid responsiveness in postherpetic neuralgia, a pure neuropathic condition. In a study that some interpret as an indictment against opioid use in noncancer pain, Schofferman (1993) found a subset of chronic low back pain patients, who had been referred to a specialty pain clinic-specifically those with structural disease-who demonstrated a beneficial response to long-term opioid therapy.
That no clinically evaluable predictor of uniform opioid responsiveness exists becomes readily apparent the more frantically we scrutinize the literature. However, as Turk et al. (1992) pointed out, interrogation of the “troops in the field” reveals how prevalent opioid use is among APS members who treat chronic pain disorders on a daily basis. So numerous are the anecdotal reports of successful (and unsuccessful) opioid treatment of chronic noncancer pain that they probably could litter the journals for months on end. We all await the day that the definitive, prospective study is finally published, and the issue is put to rest. Until then, to those purists who persist in pointing out the shadow of an infiltrate on the X ray, the rest of us say, “Treat the patient, not the X ray!"
Arner, S., & Meyerson, B.A. (1988). Lack of analgesic effect of opioids on neuropathic and idiopathic forms of pain. Pain, 33, 11-23.
Bruera, E., Macmillan, D., Hanson, J., & MacDonald, R.N. (1989). The Edmonton staging system for cancer pain: Preliminary report. Pain, 37, 203-210.
Cherny, N.I., Thaler H.T., Friedlander-Klar, H., Lapin, J., Foley, K.M., Houde, R., & Portenoy, R.K. (1994). Opioid responsiveness of cancer pain syndromes caused by neuropathic or nociceptive mechanisms: A combined analysis of controlled, single-dose studies. Neurology, 44, 857-861.
Joranson, D.E. (1995). State medical board guidelines for treatment of intractable pain. APS Bulletin 5(3), 1-5.
Kupers, R.C., Konings, H., Adriaensen, H., & Gybels, J.M. (1991). Morphine differentially affects the sensory and affective pain ratings in neurogenic and idiopathic forms of pain. Pain, 47, 5-12.
McQuay, H.J., Jadad, A.R., Carroll, D., Faura, C., Glynn, C.J., Moore, R.A., & Liu, Y. (1992). Opioid sensitivity of chronic pain: A patient-controlled analgesia method. Anaesthesia, 47, 757-767.
Merskey, H. (1979). Pain terms: A list with definitions and a note on usage. Recommended by the International Association for the Study of Pain (IASP) Subcommittee on Taxonomy. Pain, 6, 249-252.
Portenoy, R.K. (1994). Opioid therapy for nonmalignant pain. In H.L. Fields & J.C. Liebeskind (Eds.), Progress in pain research and management (Vol. 1, pp. 247-287). Seattle: IASP Press.
Portenoy, R K., Foley, K.M., & Inturrisi, C.E. (1990). The nature of opioid responsiveness and its implications for neuropathic pain: New hypotheses derived from studies of opioid infusions. Pain, 43, 273-286.
Rowbotham, M.C., Reisner-Keller, L.A., & Fields, H.L. (1991). Both intravenous lidocaine and morphine reduce the pain of postherpetic neuralgia. Neurology, 41, 1024-1028.
Schofferman, J. (1993). Long-term use of opioid analgesics for the treatment of chronic pain of nonmalignant origin. Journal of Pain and Symptom Management, 8, 279-288.
Stein, C. (1996). Opioid treatment of chronic noncancer pain: Point-counterpoint-What is the evidence of efficacy? APS Bulletin, 6(2), 10, 12-13.
Turk, D.C., & Brody, M.C. (1992). What position do APS's physician members take on chronic opioid therapy? APS Bulletin, 2(1), 1-5.
Turk, D.C., Brody, M.C., & Okifuji, E.A. (1994). Physicians' attitudes and practices regarding the long-term prescribing of opioids for noncancer pain. Pain, 59, 201-208.
Zenz, M., Strumpf, M., & Tryba, M. (1992). Long-term opioid therapy in patients with chronic nonmalignant pain. Journal of Pain and Symptom Management, 7, 69-77.
Mark Stillman is medical director of the Hospice of Seattle and instructor at the University of Washington School of Medicine in Seattle.
