Kathleen M. Foley

Pain measurement: an overview

&NA; The practice and theoretical basis of pain measurement is reviewed and critically examined in the areas of animal research, human subjects laboratory investigation and clinical study. The advantages and limitations of both physiological and behavioral methods are discussed in each area, and subjective report procedures are evaluated in human laboratory and clinical areas. The need for procedures that bridge these areas is emphasized and specific issues are identified. Progress in the technology of pain measurement over recent decades is reviewed and directions for future work are suggested.

The Treatment of Cancer Pain

Pain is one of the most feared consequences of cancer. Control of pain from cancer should be possible with the approaches discussed above. Changing attitudes toward the effective use of narcotic analgesics, the development of novel routes and methods of administration, and a clinical approach based on scientific principles and humane care offer the promise of improved management of pain in patients with cancer.

Chronic use of opioid analgesics in non-malignant pain: Report of 38 cases

&NA; Thirty‐eight patients maintained on opioid analgesics for non‐malignant pain were retrospectively evaluated to determine the indications, course, safety and efficacy of this therapy. Oxycodone was used by 12 patients, methadone by 7, and levorphanol by 5; others were treated with propoxyphene, meperidine, codeine, pentazocine, or some combination of these drugs. Nineteen patients were treated for four or more years at the time of evaluation, while 6 were maintained for more than 7 years. Two‐thirds required less than 20 morphine equivalent mg/day and only 4 took more than 40 mg/day. Patients occasionally required escalation of dose and/or hospitalization for exacerbation of pain; doses usually returned to a stable baseline afterward. Twenty‐four patients described partial but acceptable or fully adequate relief of pain, while 14 reported inadequate relief. No patient underwent a surgical procedure for pain management while receiving therapy. Few substantial gains in employment or social function could be attributed to the institution of opioid therapy. No toxicity was reported and management became a problem in only 2 patients, both with a history of prior drug abuse. A critical review of patient characteristics, including data from the 16 Personality Factor Questionnaire in 24 patients, the Minnesota Multiphasic Personality Inventory in 23, and detailed psychiatric evaluation in 6, failed to disclose psychological or social variables capable of explaining the success of long‐term management. We conclude that opioid maintenance therapy can be a safe, salutary and more humane alternative to the options of surgery or no treatment in those patients with intractable non‐malignant pain and no history of drug abuse.

The nature of opioid responsiveness and its implications for neuropathic pain: new hypotheses derived from studies of opioid infusions

&NA; In recent years, the observation that the response of patients to opioid drugs may be influenced by properties inherent in the pain or pain syndrome, such as its pathophysiology, has evolved into the belief that certain types of pain e.g., neuropathic pains, may be unresponsive to these drugs. This concept has important implications for both clinical practice and basic understanding of opioid mechanisms. We critically evaluate opioid responsiveness, particularly as it relates to neuropathic pain, and propose a clinically relevant definition and a paradigm for its investigation. The paradigm is illustrated by analgesic responses to opioid infusion in 28 patients with neuropathic pains and by a detailed presentation of the pharmacokinetic and pharmacodynamic relationships in one of these patients, whose central pain responded promptly to an infusion of hydromorphone. From this analysis, we hypothesize that (1) opioid responsiveness in man can be defined by the degree of analgesia achieved during dose escalation to either intolerable side effects or the occurrence of ‘complete’ or ‘adequate’ analgesia; (2) opioid responsiveness is a continuum, rather than a quantal phenomenon; (3) opioid responsiveness is determined by a diverse group of patient characteristics and pain‐related factors, as well as drug‐selective effects; and (4) a neuropathic mechanism may reduce opioid responsiveness, but does not result in an inherent resistance to these drugs. Given the complexity of factors contributing to opioid responsiveness and the observation that outcome cannot be reliably predicted, opioids should not be withheld on the assumption that pain mechanism, or any other factor, precludes a favorable response. Both the clinical use of opioids and paradigms to investigate opioid responsiveness should include dose escalation to maximally tolerated levels and repeated monitoring of analgesia and other effects.

Character of terminal illness in the advanced cancer patient: Pain and other symptoms during the last four weeks of life

There is a great variability among advanced cancer patients in the experience of symptoms and their impact on lifes activities. A subgroup of difficult patients particularly tax the clinical skills and compassion of practitioners. Although the need for information about these patients is evident, their characteristics have not been explored heretofore. We describe our experience with such patients, a group referred to the Supportive Care Program of the Pain Service at Memorial Sloan-Kettering Cancer Center. Prevalence of pain and other symptoms, patterns of opioid use and routes of drug administration, and the prevalence of suicidal ideation and requests for euthanasia are discussed.

College on Problems of Drug Dependence taskforce on prescription opioid non-medical use and abuse: position statement

This position paper from the College on Problems of Drug Dependence addresses the issues related to non-medical use and abuse of prescription opioids. A central theme throughout is the need to strike a balance between risk management strategies to prevent and deter prescription opioid abuse and the need for physicians and patients to have appropriate access to opioid pharmaceuticals for the treatment of pain. The epidemiology of prescription opioid use and abuse is reviewed. Non-medical use and abuse of prescription opioids are on the rise in the United States, illicit use of several widely prescribed opioids has increased disproportionately more than illicit use, and the prevalence of prescription opioid abuse appears to be similar to that of heroin and cocaine abuse. There is a paucity of abuse liability testing of prescription opioids, and methods should be developed to fill critical gaps in our knowledge in this area. The role of regulatory agencies in preventing diversion of prescription opioids and identifying potential sources of diversion are discussed. More research is needed to identify those populations most at risk for abusing prescription opioids, and then to develop appropriately targeted prevention programs. Treatment options are discussed; these depend on whether or not an abuser is in pain. Prescription opioid abuse has harmful ramifications for the legitimate and appropriate use of opioids, including stigmatization, opiophobia, and undertreatment of pain. Recommended steps to take include further epidemiological research, laboratory testing of prescription opioids to determine abuse liability, and clinical trials to determine the efficacy of different approaches to the prevention and treatment of prescription opioid abuse.

The memorial pain assessment card. A valid instrument for the evaluation of cancer pain

Effective evaluation and treatment of cancer pain require valid and independent measurement of pain intensity, pain relief, and psychological distress. The Memorial Pain Assessment Card (MPAC) is a simple instrument designed to provide rapid evaluation of these subjective experiences. On the 8.5 by 11 inch card are printed the eight pain intensity descriptors, and three visual analog scales which measure pain intensity, pain relief, and mood. Experienced patients can complete it in less than 20 seconds. The authors administered the MPAC to 50 hospitalized cancer patients within 48 hours of referral to the Pain Service for inadequate pain control, together with standard measures: The McGill Pain Questionnaire, Profile of Mood States, Hamilton Depression Scale, and Zung Anxiety Scale. Correlational and multiple regression analyses revealed that the MPAC can distinguish pain intensity from pain relief and from general psychological distress, and it can provide multidimensional assessment that is practically equivalent to the full assessment battery. We conclude that the MPAC is valid and effective for clinical use, and recommend it for the assessment of individual patients, and as an outcome measure in clinical trials.

Attitudes and Practices Among Pediatric Oncologists Regarding End-of-Life Care: Results of the 1998 American Society of Clinical Oncology Survey

PURPOSE In 1998, the American Society of Clinical Oncology (ASCO) surveyed its membership to assess the attitudes, practices, and challenges associated with end-of-life care of patients with cancer. In this report, we summarize the responses of pediatric oncologists and the implications for care of children dying from cancer. METHODS The survey consisted of 118 questions, covering eight categories. All ASCO members in the United States, Canada, and the United Kingdom were mailed a survey, which was completed by 228 pediatric oncologists. Predictors of particular attitudes and practices were identified using stepwise logistic regression analysis. Potential predictors were age, sex, religious affiliation, importance of religious beliefs, recent death of a relative, specialty, type of practice (rural or urban, academic or nonacademic), amount of time spent in patient care, number of new patients in the past 6 months, and number of patients who died in the past year. RESULTS Pediatric oncologists reported a lack of formal courses in pediatric palliative care, a strikingly high reliance on trial and error in learning to care for dying children, and a need for strong role models in this area. The lack of an accessible palliative care team or pain service was often identified as a barrier to good care. Communication difficulties exist between parents and oncologists, especially regarding the shift to end-of-life care and adequate pain control. CONCLUSION Pediatric oncologists are working to integrate symptom control, psychosocial support, and palliative care into the routine care of the seriously ill child, although barriers exist that make such comprehensive care a challenge.

SUBLINGUAL ABSORPTION OF SELECTED OPIOID ANALGESICS

Ongoing interest in the improvement of pain management with opioid analgesics has led to the investigation of sublingual opioid absorption. The present report determined the percent absorption of selected opioid analgesics from the oral cavity of normal subjects under conditions of controlled pH and swallowing when a 1.0 ml aliquot of the test drug was placed under the tongue for a 10‐minute period. Compared with morphine sulfate at pH 6.5 (18% absorption), buprenorphine (55%), fentanyl (51%), and methadone (34%) were absorbed to a significantly greater extent (p < 0.05), whereas levorphanol, hydromorphone, oxycodone, heroin, and the opioid antagonist naloxone were not. Overall, lipophilic drugs were better absorbed than were hydrophilic drugs. Plasma morphine concentration‐time profiles indicate that the apparent sublingual bioavailability of morphine is only 9.0% ± 11.9% (SD) of that after intramuscular administration. In the same subjects the estimated sublingual absorption was 22.4% ± 9.2% (SD), indicating that the sublingual absorption method may overestimate apparent bioavailability. When the oral cavity was buffered to pH 8.5, methadone absorption was increased to 75%. Thus, an alkaline pH microenvironment that favors the unionized fraction of opioids increased sublingual drug absorption. Although absorption was found to be independent of drug concentration, it was contact time dependent for methadone and fentanyl but not for buprenorphine. These results indicate that although the sublingual absorption and apparent sublingual bioavailability of morphine are poor, the sublingual absorption of methadone, fentanyl, and buprenorphine under controlled conditions is relatively high.

Brachial plexus lesions in patients with cancer: 100 cases.

In patients with cancer, brachial plexus signs are usually caused by tumor infiltration or injury from radiation therapy (RT). We analyzed 100 cases of brachial plexopathy to determine which clinical criteria helped differentiate tumor from radiation injury. Seventy-eight patients had tumor (34 with previous RT), and 22 had radiation injury. Severe pain occurred in 8Wo of tumor patients but in only 19% of patients with radiation injury. The lower trunk (C7-8, T1) was involved in 72% of the tumors, and 32% also had epidural tumors. Seventy-eight percent of the radiation injuries affected the upper plexus (C5-6). Horner syndrome was more common in tumor, and lymph-edema in radiation injury. The time from RT to onset of plexus symptoms, and the dose of RT, also differed. For symptoms within 1 year of RT, doses exceeding 6000 R were associated with radiation damage, whereas lower doses were associated with infiltration. Therefore, painless upper trunk lesions with lymphedema suggest radiation injury, and painful lower trunk lesions with Horner syndrome imply tumor infiltration.