Randomised trial of oral morphine for chronic non-cancer pain

Integrating pain management in clinical practice

There is much evidence to suggest that psychological and social issues are predictive of pain severity, emotional distress, work disability, and response to medical treatments among persons with chronic pain. Psychologists can play an important role in the identification of psychological and social dysfunction and in matching personal characteristics to effective interventions as part of a multidisciplinary approach to pain management, leading to a greater likelihood of treatment success. The assessment of different domains using semi-structured clinical interviews and standardized self-report measures permits identification of somatosensory, emotional, cognitive, behavioral and social issues in order to facilitate treatment planning. In this paper, we briefly describe measures to assess constructs related to pain and intervention strategies for the behavioral treatment of chronic pain and discuss related psychiatric and substance abuse issues. Finally, we offer a future look at the role of integrating pain management in clinical practice in the psychological assessment and treatment for persons with chronic pain.

Risk factor assessment for problematic use of opioids for chronic pain

Opioid analgesics provide effective treatment for noncancer pain, but many health providers have concerns about cognitive effects, tolerance, dependence, and addiction. Misuse of opioids is prominent in patients with chronic pain and early recognition of misuse risk could help providers offer adequate patient care while implementing appropriate levels of monitoring to reduce aberrant drug-related behaviors. Many persons with chronic pain also have significant medical and psychiatric comorbidities that affect treatment decisions. Neuropsychologists can play an important role in the identification of psychological and social dysfunction and in matching personal characteristics to effective interventions as part of a multidisciplinary approach to pain management. The assessment of different domains using semi-structured interviews, sensory and neuropsychological testing, and standardized self-report measures permits identification of somatosensory, emotional, cognitive, behavioral, and social issues in order to facilitate treatment planning. In this review we discuss opioid abuse and misuse issues that often arise in the treatment of patients with chronic pain, and present an overview of assessment and treatment strategies that can be effective in improving outcomes associated with the use of prescription opioids for pain. Finally we briefly discuss the effect of opiate analgesics on cognition and review some intervention strategies for chronic pain patients.

Molecular and cellular mechanisms of the age-dependency of opioid analgesia and tolerance

The age-dependency of opioid analgesia and tolerance has been noticed in both clinical observation and laboratory studies. Evidence shows that many molecular and cellular events that play essential roles in opioid analgesia and tolerance are actually age-dependent. For example, the expression and functions of endogenous opioid peptides, multiple types of opioid receptors, G protein subunits that couple to opioid receptors, and regulators of G protein signaling (RGS proteins) change with development and age. Other signaling systems that are critical to opioid tolerance development, such as N-methyl-D-aspartic acid (NMDA) receptors, also undergo age-related changes. It is plausible that the age-dependent expression and functions of molecules within and related to the opioid signaling pathways, as well as age-dependent cellular activity such as agonist-induced opioid receptor internalization and desensitization, eventually lead to significant age-dependent changes in opioid analgesia and tolerance development.

Neuropsychological assessment of chronic non-malignant pain patients treated in a multidisciplinary pain centre

The aim of the study was to investigate the influence of pain, sedation, pain medications and socio-demographics on cognitive functioning in chronic non-malignant pain patients. Chronic non-malignant pain patients (N=91) treated in a multidisciplinary pain centre were compared with age and sex matched healthy volunteers (N=64). Furthermore four subgroups of patients were examined: Group 1 (N=21) received no pain medications, group 2 (N=19) were in long-term oral opioid treatment, group 3 (N=18) were treated with antidepressants and/or anticonvulsants and group 4 (N=33) were treated with a combination of long-term oral opioids and antidepressants and/or anticonvulsants. Assessments comprised pain (PVAS) and sedation (SVAS), Continuous Reaction Time (CRT) testing for sustained attention, Finger Tapping Test (FTT) testing for psychomotor speed, Paced Auditory Serial Addition Task (PASAT) testing for information processing and working memory and Mini Mental State Examination (MMSE). CRT and FTT were impaired in the total patient sample. Treatment with opioids was associated with poorer performance of PASAT. High scores of PVAS and SVAS were associated with poor performance of PASAT and CRT, respectively. MMSE seems to be too insensitive for detecting the milder forms of cognitive impairment found in chronic non-malignant patients.

Reduction of human experimental muscle pain by alfentanil and morphine

Musculoskeletal pain is a major clinical problem. By using various experimental models in humans, the understanding of the basic mechanisms behind muscle pain can increase, thereby giving hope for new and optimized treatment. Opioids are increasingly often used to treat muscle pain. There are, however, a limited number of previous studies on opioids and muscle pain, most of them using a relative low, single dose. Therefore, we wanted to further study the effect of two rather high doses of alfentanil (25 and 75ng/ml) and morphine (0.14 and 0.28mg/kg) in human volunteers. The study consisted of two parallel studies with morphine and alfentanil, respectively, and was conducted as randomized, double-blinded, placebo-controlled, 3-way cross-over. We used intramuscular infusion of hypertonic saline and intramuscular electrical stimulation to induce experimental pain. Visual analog scale (VAS)-score, intramuscular electrical pain thresholds and pain area (local and referred) were measured. Both alfentanil and morphine at their highest doses induced a 6 to 7-fold increase in pain thresholds to single and repetitive (5 stimulations, 2Hz) electrical stimulation. Alfentanil and morphine also reduced VAS score about 4 to 5-fold during suprathreshold electric stimulation and during infusion of hypertonic saline. None of the drugs decreased referred pain. There were no apparent differences between the drugs, in terms of effect or adverse reactions. In conclusion, this is the first study to compare two high doses of alfentanil and morphine on experimental muscle pain in humans. Both alfentanil and morphine reduced experimental muscle pain. There were no indications of any true pharmacodynamic differences between the two drugs.

A comparison between enriched and nonenriched enrollment randomized withdrawal trials of opioids for chronic noncancer pain

BACKGROUND

An enriched enrollment randomized withdrawal (EERW) design excludes potential participants who are nonresponders or who cannot tolerate the experimental drug before random assignment. It is unclear whether EERW design has an influence on the efficacy and safety of opioids for chronic noncancer pain (CNCP).

OBJECTIVES

The primary objective was to compare the results from EERW and non-EERW trials of opioids for CNCP. Secondary objectives were to compare weak versus strong opioids, subgroups of patients with different types of pain, and the efficacy of opiods compared with placebo versus other drugs.

METHODS

MEDLINE, EMBASE and CENTRAL were searched up to July 2009, for randomized controlled trials of any opioid for CNCP. Metaanalyses and meta-regressions were conducted to compare the results. Treatment efficacy was assessed by effect sizes (small, medium and large) and the incidence of adverse effects was assessed by a clinically relevant mean difference of 10% or greater.

RESULTS

Sixty-two randomized trials were included. In 61 trials, the duration was less than 16 weeks. There was no difference in efficacy between EERW and non-EERW trials for both pain (P=0.6) and function (P=0.3). However, EERW trials failed to detect a clinically relevant difference for nausea, vomiting, somnolence, dizziness and dry skin⁄itching compared with non-EERW. Opioids were more effective than placebo in patients with nociceptive pain (effect size=0.60, 95% CI 0.49 to 0.72) and neuropathic pain (effect size=0.56, 95% CI 0.38 to 0.73).

CONCLUSION

EERW trial designs appear not to bias the results of efficacy, but they underestimate the adverse effects. The present updated meta- analysis shows that weak and strong opioids are effective for CNCP of both nociceptive and neuropathic origin.

Assessment and treatment of abuse risk in opioid prescribing for chronic pain

Opioid analgesics provide effective treatment for noncancer pain, but many physicians have concerns about adverse effects, tolerance, and addiction. Misuse of opioids is prominent in patients with chronic back pain and early recognition of misuse risk could help physicians offer adequate patient care while implementing appropriate levels of monitoring to reduce aberrant drug-related behaviors. In this review, we discuss opioid abuse and misuse issues that often arise in the treatment of patients with chronic back pain and present an overview of assessment and treatment strategies that can be effective in improving compliance with the use of prescription opioids for pain. Many persons with chronic back pain have significant medical, psychiatric and substance use comorbidities that affect treatment decisions and a comprehensive evaluation that includes a detailed history, physical, and mental health evaluation is essential. Although there is no "gold standard" for opioid misuse risk assessment, several validated measures have been shown to be useful. Controlled substance agreements, regular urine drug screens, and interventions such as motivational counseling have been shown to help improve patient compliance with opioids and to minimize aberrant drug-related behavior. Finally, we discuss the future of abuse-deterrent opioids and other potential strategies for back pain management.

Enhanced analgesic responses after preferential delivery of morphine and fentanyl to the olfactory epithelium in rats

BACKGROUND

Centrally acting opioid analgesics such as morphine and fentanyl are effective, but their efficacy is often limited by a delayed response or side effects resulting from systemic first pass before reaching the brain and the central nervous system (CNS). It is generally accepted that drugs applied to the nasal cavity can directly access the brain and the CNS, which could provide therapeutic advantages such as rapid onset and lower systemic exposure. The olfactory region of the nasal cavity has been implicated in facilitating this direct nose-to-CNS transfer. If the fraction of opioid administered to the olfactory region could be improved, there could be a larger fraction of drug directly delivered to the CNS, mediating greater therapeutic benefit.

METHODS

We have developed a pressurized olfactory delivery (POD) device to consistently and noninvasively deposit a majority of drug on the olfactory region of the nasal cavity in Sprague-Dawley rats. Using the tail-flick latency test and analysis of plasma and CNS tissue drug exposure, we compared distribution and efficacy of the opioids morphine and fentanyl administered to the nasal olfactory region with the POD device or the nasal respiratory region with nose drops or systemically via intraperitoneal injection.

RESULTS

Compared with nose drop administration, POD administration of morphine resulted in a significantly higher overall therapeutic effect (area under the curve [over the time course] [AUC](effect)) without a significant increase in plasma drug exposure (AUC(plasma)). POD of morphine resulted in a nose-to-CNS direct transport percentage of 38% to 55%. POD of fentanyl led to a faster (5 vs 10 minutes) and more intense analgesic effect compared with nasal respiratory administration. Unlike intraperitoneal injection or nose drop administration, both morphine and fentanyl given by the POD device to olfactory nasal epithelium exhibited clockwise (plasma) versus effect hysteresis after nasal POD administration, consistent with a direct nose-to-CNS drug transport mechanism.

CONCLUSIONS

Deposition of opioids to the olfactory region within the nasal cavity could have a significant impact on drug distribution and pharmacodynamic effect, and thus should be considered in future nasally administered opioid studies.

The impact of fentanyl matrix on pain and function in spinal disorder-related chronic pain: an open label trial in Korea

Study Design

This is a multicenter, open-label prospective, non interventional study.

Purpose

We wanted to evaluate the impact of fentanyl matrix on the pain and function of patients with spinal disorder-related chronic, non-malignant pain.

Overview of Literature

Patients with severe non-malignant chronic low back pain may require opioid analgesics for effective pain management.

Methods

A total of 1,576 patients with severe pain (numeric rating scale = 7) were evaluated for their pain intensity at the initial visit and at weeks 4 and 8 (Visits 1, 2, and 3, respectively). Disturbances in sleep, daily living and social activities, the Oswestry Disability Index (ODI), the researchers' and patients' global assessment and the patients' treatment preference were also assessed.

Results

The pain intensity score significantly decreased from 8.1 at Visit 1 to 5.4 and 4.4 at Visits 2 and 3, respectively. Sleep disturbance also significantly decreased and the extent of disturbance of daily and social activities was also significantly improved. The ODI significantly decreased from 61.9% to 45.8% and 38.2% at Visits 1, 2, and 3, respectively. Adverse events were reported by 197 (12.5%) patients and severe adverse events were reported by 12 (0.76%) patients. Overall, 76.3% of the patients and 78.4% of the investigators rated the test drug as effective.

Conclusions

The fentanyl matrix is believed to be effective for the treatment of pain, sleep disturbance and the impact upon daily and social activities, yet physicians should pay attention to the risks of abuse and the adverse events.

Observational, nonintervention, multicenter study for validation of the Bowel Function Index for constipation in European countries

OBJECTIVE

Constipation is a common adverse event of treatment with opioids for chronic non-malignant pain and may result in a considerable reduction in health-related quality of life. The aim of this study was to assess the psychometric properties of the Bowel Function Index (BFI) in european patients suffering from constipation secondary to opioid analgesic treatment for chronic, non-malignant pain.

METHODS

This was a multinational study conducted at 15 clinical sites in the Czech Republic, Germany, Italy, and the United Kingdom. Patients suffering from constipation secondary to opioid analgesic treatment for chronic, non-malignant pain were recruited to complete a series of questionnaires including a socio-demographic form, the BFI, the Patient Assessment of Constipation - Symptoms (PAC-SYM), a global frequency item, and a clinical form.

RESULTS

A total of 131 patients were included in this study. Inter-item correlations of the BFI were statistically significant in the moderate to large range and the analysis indicated a strong degree of internal consistency (Cronbach's alpha = 0.86). All correlations between the BFI and the global item were statistically significant in the moderate to high range (r = 0.59 to 0.69; p < 0.0001). Correlations between the BFI and the PAC-SYM were moderate and statistically significant (p < 0.01 to 0.0001).

CONCLUSIONS

Although this study was limited by the relatively small sample size, it is a part of an extensive validation program. This study suggests that the BFI is a reliable and valid measure of constipation-related symptomatology in chronic pain patients. This measure may be a valuable indicator of patients' experience of symptoms of opioid treatment of chronic pain in future trials.

Evaluation of efficacy and safety of fentanyl transdermal patch (Durogesic D-TRANS) in chronic pain

PURPOSE

Opioids are used in controlling several types of pain. This study was designed to evaluate the efficacy and safety of the fentanyl transdermal patch-type system (Durogesic® D-TRANS).

METHODS

Patients who complained of chronic moderate to severe pain were enrolled. Administration dosages of fentanyl patch started from 12.5 μg/h and could be increased by 12.5 μg/h or 25 μg/h, if the average pain score of 4 or higher occurred within 72 h. The total administration period was 12 weeks. The type, location, characteristics, and duration of pain were evaluated. Also, on day 0, weeks of 4, 8, and 12, the physician's assessment of pain intensity, the patient's assessment of pain intensity, the assessment of impact of pain on functions, and the assessment of the impact of pain on sleep were assessed. In addition, side effects were evaluated during the study duration.

RESULTS

A total of 65 cases were enrolled, and the final evaluated cases were 41. Before treatment, the average physician's assessment of pain intensity was 6.70 ± 1.41, and the average patient's assessment of pain intensity was 7.02 ± 1.63. In the final visit, the average physician's assessment of pain intensity was 2.58 ± 1.72, and the average patient's assessment of pain intensity was 2.86 ± 1.78.

CONCLUSIONS

This prospective study shows that the fentanyl patch is effective in alleviating moderate to severe chronic noncancer pain including neuropathic pain down to mild pain. Therefore, the fentanyl patch should be considered before other invasive intervention procedures in chronic moderate to severe noncancer pain.

Negligible analgesic tolerance seen with extended release oxymorphone: a post hoc analysis of open-label longitudinal data

OBJECTIVE

To examine the development of analgesic tolerance in patients on oxymorphone extended-release (OxymER).

DESIGN

Post hoc analysis of data from a previously conducted prospective 1 year multi-center open-label extension study in which patients were able to titrate as needed.

PATIENTS

Sample of 153 hip and knee osteoarthritis (OA) subjects on OxymER. Primary analyses were limited to study completers (n = 62) due to the large amount of missing data for the noncompleters (n = 91).

OUTCOME MEASURES

Main outcome measures included OxymER doses (pill counts) and pain intensity ratings using a visual analog scale at monthly visits.

RESULTS

There were significant dose increases from weeks 1 to 2 and 2 to 6 (P < 0.05). Doses stabilized around week 6, suggesting the completion of what we defined as "titration." Both doses and pain ratings were stable when this titration phase was excluded from the analysis (P = 0.751; P = 0.056, respectively). Only 28% of the patients had any dose changes following this titration. While there was a significantly greater dose at week 52 compared with week 10 (P = 0.010), the increase in dose became insignificant after excluding four subjects who required two dose increases (P = 0.103).

CONCLUSIONS

The results showed that most of the titration/dose stabilization changes occurred within the first 10 weeks. A minority (28%) of subjects required dosage increases after this (defined) titration period. Pain reports stabilized statistically after 2 weeks. The findings of this post hoc analysis suggest a lack of opioid tolerance in the majority (72%) of these OA patients who completed this study following a defined titration period on OxymER.

SUMMARY

This post hoc analysis of oxymorphone ER consumption in osteoarthritis pain vs pain report showed that most dose changes occurred during an initial "titration period" as defined. Following this titration few subjects increased dose and analgesia remained stable. These findings suggest a lack of longitudinal opioid tolerance in the majority of those OA subjects who completed the trial.

Iatrogenic disability and narcotics addiction after lumbar fusion in a worker's compensation claimant

STUDY DESIGN

Case report.

OBJECTIVE

Describe a case of chronic occupational low back pain with various treatments of questionable efficacy, leading to prolonged disability, iatrogenic narcotic addiction, and opioid-induced hyperalgesia.

SUMMARY OF BACKGROUND DATA

Concerns about narcotics and other questionable treatments for chronic low back pain are increasing, especially in those with work-related conditions.

METHODS

Medical record review.

RESULTS

The patient had significant, persistent low back symptoms, but good function at work and home. He underwent lumbar fusion to address persistent pain, and subsequently developed failed back surgery syndrome. He was prescribed increasing amounts of opioid analgesics and was recommended for an intrathecal morphine pump, without evaluation of the safety or efficacy of his current regimen. Subsequently, he was hospitalized for opioid detoxification and substance abuse treatment.

CONCLUSION

Patients with chronic low back pain are at risk for receiving ineffective and potentially harmful treatment. A focus on restoring function instead of complete pain relief may lead to better outcomes in these patients.

Opioid-induced bowel disorders and narcotic bowel syndrome in patients with chronic non-cancer pain

BACKGROUND

Opioids are used increasingly in the management of moderate-to-severe chronic non-cancer pain (CNCP). Opioid-induced bowel disorders (OBD) markedly impact health-related quality of life (HRQoL) and frequently limit medically indicated opioid pharmacotherapy. We assessed the risk factors, and effect of OBD on HRQoL in CNCP patients. We also estimated the likely prevalence of narcotic bowel syndrome (NBS). These effects have been reported in cancer patients but not in CNCP previously.

METHODS

Ambulatory CNCP patients (n = 146) taking regularly scheduled opioids were invited to complete the Bowel-Disease-Questionnaire and a pain-sensitive HRQoL instrument. The Rome-II criteria were used to define bowel disorders. Narcotic bowel syndrome was defined as presence of daily severe to very-severe abdominal pain of more than 3 months duration requiring more than 100 mg of morphine equivalent per day.

KEY RESULTS

Ninety-eight patients (69%) returned the survey. Respondents had taken opioids for 10 days to 10 years (median 365 days) at a median daily dose of 127.5 mg morphine-equivalent (range 7.5-600 mg). Constipation prevalence was 46.9% (95% CI 36.8-57.3), nausea 27% (95% CI 17.2-35.3), vomiting 9% (95% CI 17.2-35.3), and gastro-esophageal reflux disease 33% (95% CI 23.5-42.9). Chronic abdominal pain was reported by 58.2% (95% CI 53.2-73.9) and 6.4%, (95% CI 2.4-13.5) fulfilled the criteria of NBS. Prevalence of constipation increased with duration of treatment. Health-related quality of life was low in patients with chronic abdominal pain.

CONCLUSION & INFERENCES

Bowel disorders including chronic abdominal pain and NBS are common in patients taking opioids for CNCP. Decreased HRQoL in patients with CNCP is driven by chronic abdominal pain.

Understanding primary care physicians' treatment of chronic low back pain: the role of physician and practice factors

BACKGROUND

An increasing number of Operation Iraqi Freedom/Operation Enduring Freedom veterans experience chronic pain. Despite treatment guidelines, there is wide variation in physicians' approaches to pain treatment, and many physicians are unsure of the best treatment approach. Research has examined factors associated with opioid prescribing, but there is little information on physician characteristics that predict patterns of clinical responses to pain.

OBJECTIVES

To identify patterns in primary care physicians' treatment decisions for nonmalignant chronic pain, and identify physician and practice characteristics that predict treatment decision patterns.

METHODS

A national sample of 381 primary care physicians who responded to a mailed vignette involving a veteran with chronic low back pain (LBP) were categorized into latent classes by clinical actions taken to treat the pain. The associations between newly derived treatment patterns and physician and practice characteristics were examined with multivariate models.

RESULTS

Latent class analysis identified three treatment approaches: 1) Multimodal/Aggressive (14%); 2) Low Action (38%); and 3) Psychosocial/Non-Opioid (48%). In a multivariate model, treatment pattern was associated with demographic and personality factors; opioid-related attitudes, beliefs, and concerns; perceptions of the patient; availability of resources; and practice characteristics.

CONCLUSIONS

There may be distinct patterns in primary care physicians' responses to patients with chronic pain. Relatively few physicians use the multimodal approach endorsed by proponents of the biopsychosocial model of pain treatment. Several physician and practice characteristics predict patterns of clinical action.

The Role of Opioids in Managing Chronic Non-cancer Pain

The use of opioids for the treatment of chronic non-cancer pain has become more widespread recently. Available data support the short-term use of opioids in clearly defined nociceptive and neuropathic pain states. Their use in ‘pathological’ pain states without a clear diagnosis, such as chronic low back pain, is more contentious. A decision to initiate opioid treatment in these conditions requires careful consideration of benefits and risks; the latter include not only com- monly considered adverse effects such as constipation, but also opioid-induced hyperalgesia, abuse, addiction and diversion. Ideally, treatment goals should not only be relief of pain, but also improvement of function. Opioid treatment of chronic non-cancer pain requires informed consent by, and preferably a treatment contract with, the patient. Treatment should be initiated by a trial period with defined endpoints using slow-release or transdermal opioids. Ongoing management of the patient requires ideally a multi-disciplinary setting. Treatment should not be regarded as life-long and can be discontinued by tapering the dose. Key words: Neuropathic pain, Opioid-induced hyperalgesia, Pain management, Prescription drug abuse

Impact of opioid rescue medication for breakthrough pain on the efficacy and tolerability of long-acting opioids in patients with chronic non-malignant pain

Background

There is little evidence that short-acting opioids as rescue medication for breakthrough pain is an optimal long-term treatment strategy in chronic non-malignant pain. We compared clinical studies of long-acting opioids that allowed short-acting opioid rescue medication with those that did not, to determine the impact of opioid rescue medication use on the analgesic efficacy and tolerability of chronic opioid therapy in patients with chronic non-malignant pain.

Methods

We searched MEDLINE (1950 to July 2006) and EMBASE (1974 to July 2006) using terms for chronic non-malignant pain and long-acting opioids. Independent review of the search results identified 48 studies that met the study selection criteria. The effect of opioid rescue medication on analgesic efficacy and the incidence of common opioid-related side-effects were analysed using meta-regression.

Results

After adjusting for potentially confounding variables (study design and type of opioid), the difference in analgesic efficacy between the ‘rescue’ and the ‘no rescue’ studies was not significant, with regression coefficients close to 0 and 95% confidence intervals that excluded an effect of more than 18 points on a 0–100 scale in each case. There was also no significant difference between the ‘rescue’ and the ‘no rescue’ studies for the incidence of nausea, constipation, or somnolence in both the unadjusted and the adjusted analyses.

Conclusions

We found no evidence that rescue medication with short-acting opioids for breakthrough pain affects analgesic efficacy of long-acting opioids or the incidence of common opioid-related side-effects among chronic non-malignant pain patients.

Prevalence of opioid dispensings and concurrent gastrointestinal medications in Quebec

BACKGROUND

Opioids are frequently prescribed for moderate to severe pain. A side effect of opioid usage is the inhibition of gastrointestinal (GI) motility, known as opioid-induced bowel dysfunction (OBD). OBD is typically treated prophylactically with laxatives and/or acid suppressants.

AIM

The present study describes the prevalence of outpatient opioid dispensing, opioid patient demographics, and concomitant dispensing of opioids and GI medications in the Quebec Public Prescription Drug Insurance Plan in 2005.

METHODS

Using a retrospective cohort design, opioid dispensings were identified using claims and reimbursement data. Laxative and acid suppressant dispensings were also identified. Concurrent use was defined as having at least one 'GI medication-exposed day' overlapping an 'opioid-exposed day'.

RESULTS

More than 11% of the drug plan population was dispensed an opioid in 2005, and dispensings increased with age. Approximately two-thirds of patients who received an opioid were given codeine. Approximately one-third of opioid patients were concomitantly dispensed a GI medication, yet only 2% were dispensed a laxative.

CONCLUSIONS

Although the GI side effects of opioids are well known, these side effects appear to increase with age and duration of opioid use. Opioid-related side effects, particularly OBD, should be effectively managed so as not to lead to the cessation of opioid therapy.

The management of patients with painful total knee replacement

The management of patients with a painful total knee replacement requires careful assessment and a stepwise approach in order to diagnose the underlying pathology accurately. The management should include a multidisciplinary approach to the patient's pain as well as addressing the underlying aetiology. Pain should be treated with appropriate analgesia, according to the analgesic ladder of the World Health Organisation. Special measures should be taken to identify and to treat any neuropathic pain. There are a number of intrinsic and extrinsic causes of a painful knee replacement which should be identified and treated early. Patients with unexplained pain and without any recognised pathology should be treated conservatively since they may improve over a period of time and rarely do so after a revision operation.

The promotion and marketing of oxycontin: commercial triumph, public health tragedy

I focus on issues surrounding the promotion and marketing of controlled drugs and their regulatory oversight. Compared with noncontrolled drugs, controlled drugs, with their potential for abuse and diversion, pose different public health risks when they are overpromoted and highly prescribed. An in-depth analysis of the promotion and marketing of OxyContin illustrates some of the associated issues. Modifications of the promotion and marketing of controlled drugs by the pharmaceutical industry and an enhanced capacity of the Food and Drug Administration to regulate and monitor such promotion can have a positive impact on the public health.

Validation of a French-Canadian version of the Pain Disability Index

OBJECTIVE

To examine the psychometric properties of the Index de l'incapacité reliée à la douleur, a French-Canadian version of the Pain Disability Index (PDI).

METHODS

A total of 176 chronic pain patients (94 women, 82 men) completed the French-Canadian version of the PDI (PDI-CF), as well as other pain-related measures. A subset of 52 patients (27 women, 25 men) also completed a lifting task designed to assess physical tolerance and pain behaviour.

RESULTS

Confirmatory factor analysis of the PDI-CF supported the two-factor structure of the original PDI. Reliability analyses revealed that the PDI-CF total score had a high degree of internal consistency, comparable with the original PDI. The PDI-CF total score was significantly correlated with self-reported pain, pain catastrophizing, depressive symptoms, fear of movement or (re)injury, lift duration and pain behaviours.

CONCLUSIONS

The results suggest that the PDI-CF is a reliable and valid measure of self-reported disability that is psychometrically similar to the original scale.

Efficacy of opioids for chronic pain: a review of the evidence

Opioid therapy for chronic pain has been popularized over the past few decades, and a concern has arisen that the analgesic efficacy of opioids is not always maintained over prolonged courses of treatment despite dose escalation and stable pain. Considering the potentially serious adverse effects of opioids, the idea that pain relief could diminish over time may have a significant impact on the decision to embark on this therapy, especially in vulnerable individuals. Possible loss of analgesic efficacy is especially concerning, considering that dependence may make it hard to withdraw opioid therapy even in the face of poor analgesia. This article first reviews the evidence on opioid efficacy when used for the treatment of chronic pain, and concludes that existing evidence suggests that analgesic efficacy, although initially good, is not always sustained during continuous and long-term opioid therapy (months to years). The theoretical basis for loss of analgesic efficacy over time is then examined. Mechanisms for loss of analgesic efficacy proposed are pharmacologic tolerance, opioid-induced hyperalgesia, subtle and intermittent withdrawal, and a number of psychologic factors including loss of the placebo component.

Extended-release, once-daily morphine (Avinza) for the treatment of chronic nonmalignant pain: effect on pain, depressive symptoms, and cognition

OBJECTIVE

To evaluate the impact of an extended-release, once-daily morphine sulfate formulation on depressive symptoms and neurocognition in patients with chronic nonmalignant pain.

DESIGN

Prospective, open-label, one-group trial with a pretest-posttest design.

SETTING

Outpatient pain management clinic.

PATIENTS AND INTERVENTION

Chronic nonmalignant pain patients inadequately controlled with short-acting opioid analgesics and eligible for treatment with once-daily morphine sulfate were initiated on a dose at or near the morphine-equivalent dose of the short-acting regimen.

OUTCOMES

The following assessments were made at baseline and 4 weeks after initiating intervention: pain intensity, pain unpleasantness, pain suffering, pain behaviors, Beck Depression Inventory, and cognitive function.

RESULTS

Eighty-four patients provided usable data. Pain intensity, unpleasantness, and suffering scores were significantly reduced at follow-up (P = 0.001). The mean Beck Depression Inventory scores were significantly lower at follow-up (P = 0.001). Significant improvements were seen in scores at follow-up on the three validated neurocognitive tests: the digit span test, the digit symbol substitution test, and the paced auditory serial addition test (P = 0.001).

CONCLUSIONS

Achieving adequate pain control with once-daily morphine was associated with a reduction in pain and improvements in depressive symptoms and cognitive functioning in the short term.

Experience of methadone therapy in 100 consecutive chronic pain patients in a multidisciplinary pain center

OBJECTIVE

The objective of the study was to describe the experience of methadone use in 100 consecutive chronic pain patients managed in a single multidisciplinary center.

DESIGN

A chart review of chronic pain patients on methadone therapy initiated at the Wasser Pain Management Center from January 2001 to June 2004. SETTING, PATIENTS, AND INTERVENTION: Outpatients receiving methadone for chronic pain management in a tertiary multidisciplinary pain center.

OUTCOME MEASURE

Effects on pain relief and function, conversion ratio from other opioids, side effects, and disposition were reviewed.

RESULTS

Charts of 100 methadone patients (age 45 +/- 11 years old; M/F: 3/7; duration of pain 129 +/- 110 months) managed by five physicians and one nurse were reviewed. The main reason for the initiation of methadone therapy was opioid rotation (72%). The average oral morphine equivalent dose was 77 mg/day before methadone therapy, and the methadone dose after initial stabilization was 42 mg with no consistent conversion ratio observed. The mean duration of methadone therapy was 11 months. Most of the patients (91%) were taking concomitant adjuvant analgesics or psychotropic agents, mostly antidepressants and anticonvulsants. The average Numeric Verbal Rating Score before and after methadone treatment was 7.2 +/- 1.7 and 5.2 +/- 2.5 (P < 0.0001). Thirty-five patients discontinued their methadone treatment mainly because of side effects, ineffectiveness, or both.

CONCLUSION

From our experience, methadone is an effective alternative to conventional opioids for chronic pain management when used by experienced clinicians in a setting that allows for close monitoring and careful dose initiation and adjustment.

Prevention of postoperative pain and of epidural fibrosis after lumbar microdiscectomy: pilot study in a series of forty cases treated with epidural vaseline-sterile-oil-morphine compound

STUDY DESIGN

At the end of lumbar microdiscectomy, we administered an emulsion of low-dose epidural morphine and vaseline sterile-oil as carrier for morphine delivery.

OBJECTIVE

To evaluate safety and analgesic efficacy of this compound and the impact on long-term epidural scar production.

SUMMARY OF BACKGROUND DATA

Epidural analgesia has been used with lumbar microdiscectomy for facilitating management of postoperative pain, shortening patients' hospital stay and recovery time, and increasing the satisfaction rate. Several products have been used as barrier against the development of epidural fibrosis after lumbar procedures, to improve long-term outcome.

METHODS

Two milligrams of morphine mixed with 2 mL of vaseline sterile-oil have been epidurally administered to 40 consecutive patients undergoing lumbar microdiscectomy, evaluating safety and analgesic effectiveness of the compound and the incidence of epidural fibrosis at clinical and magnetic resonance imaging or computed tomography scan follow-up. Outcome measures included (1) visual analog scale (VAS) to assess the intensity of spontaneous low back and radicular pain, (2) straight-leg-raising maneuver to assess the degrees of leg elevation in relation to evoked-sciatic pain, (3) postoperative time to comfortable ambulation, (4) duration of postoperative hospitalization, (5) required amount of postoperative analgesics, (6) postoperative work time loss, and (7) follow-up lumbar magnetic resonance imaging or segmental computed tomography with contrast medium for quantitative evaluation of postoperative epidural fibrosis.

RESULTS

Neither intraoperative nor postoperative clinically relevant adverse events, such as urinary retention, respiratory disturbances, or wound infections, were observed. At hospital discharge, patients showed a low pain intensity score (mean VAS 11.3 mm +/- 0.88; mean straight-leg-raising 64.9 degrees +/- 14.6), with low consumption of analgesics (31.2% in hospital, 35% at home). Mean hospital stay was 1.21 +/- 0.17 days; mean postoperative work time loss was 22.23 +/- 1.97 days. At 1-week and 2-week control, mean pain intensity score was 10.7 +/- 2.3 and 9.3 mm +/- 1.3, respectively. After a mean follow-up of 34.3 months (range, 24-48) 12 patients episodes of transient lumbar and/or sciatic pain. At the last neuroradiological control, according to the 5-grade scale of Ross et al (Neurol Res 1999), epidural fibrosis scored 0 in 8 cases and 1 in 32 cases.

CONCLUSION

Epidural application of morphine-vaseline sterile-oil compound after lumbar microdiscectomy proved to be safe and effective, improving postoperative pain control and return to function. At clinical and neuroradiological follow-up epidural fibrosis was acceptable. To confirm the efficacy of the compound, large prospective studies are warranted.

Cognitive impairment in cancer pain patients receiving opioids: a pilot study

This study aimed to compare cognitive function of cancer pain patients being given opioids during their cancer treatment (n = 14) with that of patients receiving treatment without opioids (n = 12). Correlations between cognitive function, pain intensity, and opioid dose were analyzed. Patients were assessed 3 times in a 1-month period, using the Trail-Making Test, Mini-Mental State Examination, Digit Span, and Brief Cognitive Screening Battery. Opioid use was not associated with clear cognitive impairment. Patients being treated without opioids did perform better in the Digit Span Test reverse-order test (P = .029) and the clock drawing test (P = .023), but the differences arose in just 1 assessment in each case. Pain intensity correlated negatively with scores in the Mini-Mental State Examination (P = .001) and some Brief Cognitive Screening Battery tests (incidental recall, immediate recall, and late recall; P <or= .042) in the group receiving opioids. Opioid dose did not correlate with any of the measures of cognitive performance. However, the patients with the worst performance scores were those with more severe pain. Further studies are needed to clearly distinguish between the effects of opioids versus the effects of pain.

What percentage of chronic nonmalignant pain patients exposed to chronic opioid analgesic therapy develop abuse/addiction and/or aberrant drug-related behaviors? A structured evidence-based review

DESIGN

This is a structured evidence-based review of all available studies on the development of abuse/addiction and aberrant drug-related behaviors (ADRBs) in chronic pain patients (CPPs) with nonmalignant pain on exposure to chronic opioid analgesic therapy (COAT).

OBJECTIVES

To determine what percentage of CPPs develop abuse/addiction and/or ADRBs on COAT exposure.

METHOD

Computer and manual literature searches yielded 79 references that addressed this area of study. Twelve of the studies were excluded from detailed review based on exclusion criteria important to this area. Sixty-seven studies were reviewed in detail and sorted according to whether they reported percentages of CPPs developing abuse/addiction or developing ADRBs, or percentages diagnosed with alcohol/illicit drug use as determined by urine toxicology. Study characteristics were abstracted into tabular form, and each report was characterized according to the type of study it represented based on the Agency for Health Care Policy and Research Guidelines. Each study was independently evaluated by two raters according to 12 quality criteria and a quality score calculated. Studies were not utilized in the calculations unless their quality score (utilizing both raters) was greater than 65%. Within each of the above study groupings, the total number of CPPs exposed to opioids on COAT treatment was calculated. Similarly, the total number of CPPs in each grouping demonstrating abuse/addiction, ADRBs, or alcohol/illicit drug use was also calculated. Finally, a percentage for each of these behaviors was calculated in each grouping, utilizing the total number of CPPs exposed to opioids in each grouping.

RESULTS

All 67 reports had quality scores greater than 65%. For the abuse/addiction grouping there were 24 studies with 2,507 CPPs exposed for a calculated abuse/addiction rate of 3.27%. Within this grouping for those studies that had preselected CPPs for COAT exposure for no previous or current history of abuse/addiction, the percentage of abuse/addiction was calculated at 0.19%. For the ADRB grouping, there were 17 studies with 2,466 CPPs exposed and a calculated ADRB rate of 11.5%. Within this grouping for preselected CPPs (as above), the percentage of ADRBs was calculated at 0.59%. In the urine toxicology grouping, there were five studies (15,442 CPPs exposed). Here, 20.4% of the CPPs had no prescribed opioid in urine and/or a nonprescribed opioid in urine. For five studies (1,965 CPPs exposed), illicit drugs were found in 14.5%.

CONCLUSION

The results of this evidence-based structured review indicate that COAT exposure will lead to abuse/addiction in a small percentage of CPPs, but a larger percentage will demonstrate ADRBs and illicit drug use. These percentages appear to be much less if CPPs are preselected for the absence of a current or past history of alcohol/illicit drug use or abuse/addiction.

Chronic pain and opiates: a call for moderation

The prescription of opioid analgesics for chronic, nonterminal conditions continues as one of the most controversial and contentious issues in medicine. We have witnessed a full pendulum swing from the complete nihilism of the 1960s and 1970s to the careless zealotry of the 1990s. Neither extreme is good practice, and one hopes we are witnessing the dawn of a more moderate time of a sane and balanced appraisal of risk versus benefit in using these important tools.

OVERALL ARTICLE OBJECTIVE

To present the case for thoughtful attention and moderation in prescribing opioids to treat chronic pain conditions.

The effect of electroacupuncture on opioid-like medication consumption by chronic pain patients: a pilot randomized controlled clinical trial

Opioid-like medications (OLM) are commonly used by patients with various types of chronic pain, but their long-term benefit is questionable. Electroacupuncture (EA) has been previously shown beneficial in reducing post-operative acute OLM consumption. In this pilot randomized controlled trial, the effect of EA on OLM usage and associated side effects in chronic pain patients was evaluated. After a two-week baseline assessment, participants using OLM for their non-malignant chronic pain were randomly assigned to receive either real EA (REA, n=17) or sham EA (SEA, n=18) treatment twice weekly for 6 weeks before entering a 12-week follow-up. Pain, OLM consumption and their side effects were recorded daily. Participants also completed the McGill Pain Questionnaire (MPQ), SF-36 and Beck Depression Inventory (BDI) at baseline, and at the 5th, 8th, 12th, 16th and 20th week. Nine participants withdrew during the treatment period with another three during the follow-up period. Intention to treat analysis was applied. At the end of treatment period, reductions of OLM consumption in REA and SEA were 39% and 25%, respectively (p=0.056), but this effect did not last more than 8 weeks after treatment. There was no difference between the two groups with respect to reduction of side effects and pain and the improvement of depression and quality of life. In conclusion, REA demonstrates promising short-term reduction of OLM for participants with chronic non-malignant pain, but such effect needs to be confirmed by trials with adequate sample sizes.

Changes in morphine analgesia and side effects during daily subcutaneous administration in healthy volunteers

Tolerance to the anti-nociceptive effects of opioids develops rapidly in animals. In contrast, humans with chronic pain show little or no loss of pain relief in prospective opioid trials of 4-8 weeks duration. Employing the Brief Thermal Sensitization model to induce transient cutaneous secondary hyperalgesia, we tested the hypothesis that opioid analgesic tolerance would develop rapidly. In this outpatient randomized placebo-controlled study, subjects in the MMMMP group received two injections of subcutaneous morphine 6 mg (150 min apart) on Monday-Thursday (total 48 mg over 4 days) and matching saline placebo on Friday. Subjects in the PPPPM group received placebo on Monday-Thursday and morphine (total 12 mg) on Friday. Sixty-one healthy volunteers were enrolled; morphine side effects accounted for all nine non-completions. Compared to the first placebo day, the reduction in the area of secondary hyperalgesia on the first morphine day was significant and robust in both groups. Morphine suppression of the painfulness of skin heating and elevation of the heat pain detection threshold were also significant. During 4 days of twice-daily injections, the decline in anti-hyperalgesic effects of morphine did not reach statistical significance (p=0.06) compared to placebo. Morphine side effects did not correlate with anti-hyperalgesic effects and withdrawal symptoms did not emerge. As 4 days is the threshold for demonstrating analgesic tolerance to twice-daily morphine in animal models, a longer period of opioid exposure in healthy volunteers might be needed to detect analgesic tolerance.

Oral morphine for cancer pain

BACKGROUND

This is an updated version of a previous Cochrane review first published in Issue 4, 2003 of The Cochrane Library. Morphine has been used for many years to relieve pain. Oral morphine in either immediate release or modified release form remains the analgesic of choice for moderate or severe cancer pain.

OBJECTIVES

To determine the efficacy of oral morphine in relieving cancer pain and to assess the incidence and severity of adverse effects.

SEARCH STRATEGY

The following databases were searched: Cochrane Pain, Palliative and Supportive Care Group Trials Register (December 2006); Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2006, Issue 4); MEDLINE (1966 to December 2006); and EMBASE (1974 to December 2006).

SELECTION CRITERIA

Published randomised controlled trials (RCTs) reporting on the analgesic effect of oral morphine in adults and children with cancer pain. Any comparator trials were considered. Trials with fewer than ten participants were excluded.

DATA COLLECTION AND ANALYSIS

One review author extracted data, which was checked by the other review author. There were insufficient comparable data for meta-analysis to be undertaken or to produce numbers-needed-to-treat (NNT) for the analgesic effect.

MAIN RESULTS

In this update, nine new studies with 688 participants were added. Fifty-four studies (3749 participants) met the inclusion criteria. Fifteen studies compared oral modified release morphine (Mm/r) preparations with immediate release morphine (MIR). Twelve studies compared Mm/r in different strengths, five of these included 24-hour modified release products. Thirteen studies compared Mm/r with other opioids. Six studies compared MIR with other opioids. Two studies compared oral Mm/r with rectal Mm/r. Two studies compared MIR with MIR by a different route of administration. One study was found comparing each of the following: Mm/r tablet with Mm/r suspension; Mm/r with non-opioids; MIR with non-opioids; and oral morphine with epidural morphine. Morphine was shown to be an effective analgesic. Pain relief did not differ between Mm/r and MIR. Modified release versions of morphine were effective for 12 or 24-hour dosing depending on the formulation. Daily doses in studies ranged from 25 mg to 2000 mg with an average of between 100 mg and 250 mg. Dose titration were undertaken with both instant release and modified release products. Adverse effects were common but only 4% of patients discontinued treatment because of intolerable adverse effects.

AUTHORS' CONCLUSIONS

The randomised trial literature for morphine is small given the importance of this medicine. Most trials recruited fewer than 100 participants and did not provide appropriate data for meta-analysis. Trial design was frequently based on titration of morphine or comparator to achieve adequate analgesia, then crossing participants over in crossover design studies. It was not clear if these trials are sufficiently powered to detect any clinical differences between formulations or comparator drugs. Studies added to the review reinforce the view that it is possible to use modified release morphine to titrate to analgesic effect. There is qualitative evidence for effectiveness of oral morphine which compares well to other available opioids. There is limited evidence to suggest that transmucosal fentanyl provides more rapid pain relief for breakthrough pain compared to morphine.

The narcotic bowel syndrome: clinical features, pathophysiology, and management

Narcotic bowel syndrome (NBS) is a subset of opioid bowel dysfunction that is characterized by chronic or frequently recurring abdominal pain that worsens with continued or escalating dosages of narcotics. This syndrome is underrecognized and may be becoming more prevalent. In the United States this may be the result of increases in using narcotics for chronic nonmalignant painful disorders, and the development of maladaptive therapeutic interactions around its use. NBS can occur in patients with no prior gastrointestinal disorder who receive high dosages of narcotics after surgery or acute painful problems, and among patients with functional gastrointestinal disorders or other chronic gastrointestinal diseases who are managed by physicians who are unaware of the hyperalgesic effects of chronic opioids. The evidence for the enhanced pain perception is based on the following: (1) activation of excitatory antianalgesic pathways within a bimodal opioid regulation system, (2) descending facilitation of pain at the rostral ventral medulla and pain facilitation via dynorphin and cholecystokinin activation, and (3) glial cell activation that produces morphine tolerance and enhances opioid-induced pain. Treatment involves early recognition of the syndrome, an effective physician-patient relationship, graded withdrawal of the narcotic according to a specified withdrawal program, and the institution of medications to reduce withdrawal effects.

Chronic pain management in spine disorders

Chronic nonmalignant pain is less a symptom of a disease than a disease in itself. Accordingly, successful treatments rely less on identifying underlying pathology than on treating neural causes of pain amplification, psychologic causes of disability, and the sequelae of deconditioning and psychiatric illness. The outcome, when such treatment is provided, is remarkably favorable.

Opioids for chronic low-back pain

BACKGROUND

The use of opioids in the long-term management of chronic low-back pain (LBP) appears to be increasing. Despite this trend, the benefits and risks of these medications remain unclear.

OBJECTIVES

To determine the efficacy of opioids in adults with chronic LBP.

SEARCH STRATEGY

We electronically searched CENTRAL, CINAHL and PsycINFO to May 2006; MEDLINE and EMBASE to May 2007. We supplemented our search by reviewing references in relevant systematic reviews and identified trials.

SELECTION CRITERIA

We included randomized or quasi-randomized controlled trials assessing the use of opioids (as monotherapy or in combination with other therapies) for longer than four weeks, in adults with chronic LBP. Studies were included if they compared non-injectable opioids to other treatments. Comparisons between opioids were excluded.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed methodological quality and extracted data onto a pre-designed form. Results were statistically pooled using RevMan 4.2. We reported on pain and function using standardized mean difference (SMD) with 95% confidence interval (95% CI) and on side effects using absolute risk difference (RD) with 95% CI.

MAIN RESULTS

We included four trials. Three compared tramadol to placebo. Pooled results revealed that tramadol was more effective than placebo for pain relief, SMD 0.71 (95% CI 0.39 to 1.02), and improving function, SMD 0.17 (95% CI 0.04 to 0.30). The two most common side effects of tramadol were headaches, RD 9% (95% CI 6% to 12%) and nausea, RD 3% (95% CI 0% to 6%). One trial comparing opioids to another analgesic (naproxen) found opioids were statistically significant for relieving pain but not improving function. When re-calculated, the results were not statistically significant for either pain relief (SMD -0.58; 95% CI -1.42 to 0.26) or improving function (SMD -0.06; 95% CI -0.88 to 0.76) .

AUTHORS' CONCLUSIONS

Despite concerns surrounding the use of opioids for long-term management of chronic LBP, there remain few high-quality trials assessing their efficacy. The trials in this review, although achieving high internal validity scores, were characterized by a lack of generalizability, inadequate description of study populations, poor intention-to treat analysis, and limited interpretation of functional improvement. Based on our results, the benefits of opioids in clinical practice for the long-term management of chronic LBP remains questionable. Therefore, further high-quality studies that more closely simulate clinical practice are needed to assess the usefulness, and potential risks, of opioids for individuals with chronic LBP.