Alexander J Clark

Chronic pain in Canada--prevalence, treatment, impact and the role of opioid analgesia.

OBJECTIVE To assess the prevalence, treatment and impact of chronic pain in Canada. METHODS A stratified random sample of 2012 adult Canadians (weighted by sex, age and region according to 1996 census data) was surveyed by telephone in 2001 to determine the prevalence of chronic pain, defined as continuous or intermittent pain for at least six months. A second sample of 340 chronic pain sufferers who were taking prescription medication for their pain was studied in detail to determine current therapeutic approaches and to assess the social and economic impact of chronic pain. RESULTS Chronic noncancer pain was reported by 29% of the respondents, with increased frequency in women and older age groups. The average duration of pain was 10.7 years and the average intensity was 6.3 (on a scale from 1 to 10), with 80% reporting moderate or severe pain. Anti-inflammatory agents were prescribed for 49% of respondents and opioid analgesics were prescribed for 22% (two-thirds of these were codeine). Almost 70% were worried about addiction potential, and one-third felt that strong analgesics should be reserved for terminal illnesses. Almost one-half were unable to attend social and family events, and the mean number of days absent from work in the past year due to chronic pain was 9.3. INTERPRETATION Chronic noncancer pain is common in Canadian adults and has a major social and economic impact. Despite growing evidence supporting the efficacy and safety of major opioid analgesics for chronic noncancer pain, less than 10% of chronic pain patients taking prescription medication were treated with a major opioid. Chronic pain is undertreated in Canada, and major opioid analgesics are probably underutilized in the management of moderate to severe pain as part of a multidisciplinary treatment program.

Dimensions of catastrophic thinking associated with pain experience and disability in patients with neuropathic pain conditions

The objective of the present study was to examine the relative contributions of different dimensions of catastrophic thinking (i.e. rumination, magnification, helplessness) to the pain experience and disability associated with neuropathic pain. Eighty patients with diabetic neuropathy, post‐herpetic neuralgia, post‐surgical or post‐traumatic neuropathic pain who had volunteered for participation in a clinical trial formed the basis of the present analyses. Spontaneous pain was assessed with the sensory and affective subscales of the McGill Pain Questionnaire. Pinprick hyperalgesia and dynamic tactile allodynia were used as measures of evoked pain. Consistent with previous research, individuals who scored higher on a measure of catastrophic thinking (Pain Catastrophizing Scale; PCS) also rated their pain as more intense, and rated themselves to be more disabled due to their pain. Follow up analyses revealed that the PCS was significantly correlated with the affective subscale of the MPQ but not with the sensory subscale. The helplessness subscale of the PCS was the only dimension of catastrophizing to contribute significant unique variance to the prediction of pain. The PCS was not significantly correlated with measures of evoked pain. Catastrophizing predicted pain‐related disability over and above the variance accounted for by pain severity. The findings are discussed in terms of mechanisms linking catastrophic thinking to pain experience. Treatment implications are addressed.

Chronic Pain in Canada: Have We Improved Our Management of Chronic Noncancer Pain?

BACKGROUND Chronic noncancer pain (CNCP) is a global issue, not only affecting individual suffering, but also impacting the delivery of health care and the strength of local economies. OBJECTIVES The current study (the Canadian Chronic Pain Study II [CCPSII]) was designed to assess any changes in the prevalence and treatment of CNCP, as well as in attitudes toward the use of strong analgesics, compared with a 2001 study (the CCPSI), and to provide a snapshot of the current standards of care for pain management in Canada. METHODS Standard, computer-assisted telephone interview survey methodology was applied in two segments, ie, a general population survey and a survey targeting randomly selected primary care physicians (PCPs) who treat moderate to severe CNCP. RESULTS AND DISCUSSION The patient-reported prevalence of CNCP within Canada has not markedly changed since 2001 but the duration of suffering has decreased. There have been minor changes in regional distribution and generally more patients receive medical treatment, which includes prescription analgesics. Physicians continue to demonstrate opiophobia in their prescribing practices; however, although this is lessened relating to addiction, abuse remains an important concern to PCPs. Canadian PCPs, in general, are implementing standard assessments, treatment approaches, evaluation of treatment success and tools to prevent abuse and diversion, in accordance with guidelines from the Canadian Pain Society and other pain societies globally, although there remains room for improvement and standardization.

Topical 2% Amitriptyline and 1% Ketamine in Neuropathic Pain Syndromes A Randomized, Double-blind, Placebo-controlled Trial

Background:A double-blind, randomized, placebo-controlled 3-week study evaluated the efficacy of topical 2% amitriptyline, 1% ketamine, and a combination of both in treating patients with neuropathic pain. Methods:Ninety-two patients with diabetic neuropathy, postherpetic neuralgia, or postsurgical/posttraumatic neuropathic pain with allodynia, hyperalgesia, or pinprick hypesthesia were randomly assigned to receive one of four creams (placebo, 2% amitriptyline, 1% ketamine, or 2% amitriptyline–1% ketamine combined). The primary outcome measure was change in average daily pain intensity (baseline week vs. final week) using an 11-point numerical pain rating scale. Secondary outcomes included the McGill Pain Questionnaire, measures of allodynia and hyperalgesia, and patient satisfaction. Results:A reduction in pain scores of 1.1–1.5 units was observed in all groups, and there was no difference between groups. Blood concentrations revealed no significant systemic absorption. Minimal side effects were encountered. Conclusion:This randomized, placebo-controlled trial examining topical 2% amitriptyline, 1% ketamine, and a combination in the treatment of neuropathic pain revealed no difference between groups. Optimization of doses may be required, because another study has revealed that higher concentrations of these agents combined do produce significant analgesia.

A pilot study examining topical amitriptyline, ketamine, and a combination of both in the treatment of neuropathic Pain

ObjectiveThe involvement of ongoing peripheral activity in the generation of nociceptive input in neuropathic pain suggests that topical drug delivery may be useful as a treatment strategy. This is a pilot study providing initial information regarding the use of novel topical preparations containing amitriptyline (AMI), ketamine (KET), and a combination of both in the treatment of neuropathic pain. MethodsThe study design included a 2 day randomized, double blind, placebo controlled, 4 way cross-over trial of all treatments, followed by an open label treatment phase using the combination cream for 7 days. Twenty volunteers with chronic neuropathic pain were randomly assigned to treatment order and applied 5 mls of each topical treatment (1% AMI, 0.5% KET, combination AMI 1%/KET 0.5%, and placebo) for 2 days. Measures of pain at the end of each block included the short form McGill Pain Questionnaire (MPQ) and visual analog scales (VAS) for present pain intensity and pain relief. Eleven subjects who judged subjective improvement from any treatment in the initial trial entered the open-label trial and used the combination cream for 7 days. Pain levels were recorded daily using the same measures. Blood levels for amitriptyline and ketamine were performed at 7 days to determine whether systemic absorption had occurred. ResultsThere was no statistically significant difference from placebo after 2 days for any treatment during the double blind component of the trial. In the 11 subjects who used the combination cream, there was a statistically significant effect, with subjects reporting significantly greater analgesia by days 3 to 7 according to measures of pain and pain relief. Blood levels revealed that there was no significant systemic absorption of amitriptyline or ketamine. Only 2 subjects experienced side effects; these were minor and did not lead to discontinuation of the cream. ConclusionThis pilot study demonstrated a lack of effect for all treatments in the 2 day double blind placebo controlled trial, followed by analgesia in an open label trial in a subgroup of subjects who chose to use the combination cream for 7 days. Blood analysis revealed no significant systemic absorption of either agent after 7 days of treatment, and creams were well tolerated. A larger scale randomized trial over a longer interval is warranted to examine further effects observed in the open label trial.

Buprenorphine transdermal system for opioid therapy in patients with chronic low back pain.

OBJECTIVE The present randomized, double-blinded, crossover study compared the efficacy and safety of a seven-day buprenorphine transdermal system (BTDS) and placebo in patients with low back pain of moderate or greater severity for at least six weeks. METHODS Prestudy analgesics were discontinued the evening before random assignment to 5 microg/h BTDS or placebo, with acetaminophen 300 mg/codeine 30 mg, one to two tablets every 4 h to 6 h as needed, for rescue analgesia. The dose was titrated to effect weekly, if tolerated, to 10 microg/h and 20 microg/h BTDS. Each treatment phase was four weeks. RESULTS Fifty-three patients (28 men, 25 women, mean [+/- SD] age 54.5+/-12.7 years) were evaluable for efficacy (completed two weeks or more in each phase). Baseline pain was 62.1+/-15.5 mm (100 mm visual analogue scale) and 2.5+/-0.6 (five-point ordinal scale). BTDS resulted in lower mean daily pain scores than in the placebo group (37.6+/-20.7 mm versus 43.6+/-21.2 mm on a visual analogue scale, P=0.0487; and 1.7+/-0.6 versus 2.0+/-0.7 on the ordinal scale, P=0.0358). Most patients titrated to the highest dose of BTDS (59% 20 microg/h, 31% 10 microg/h and 10% 5 microg/h). There were improvements from baseline in pain and disability (Pain Disability Index), Pain and Sleep (visual analogue scale), Quebec Back Pain Disability Scale and Short-Form 36 Health Survey scores for both BTDS and placebo groups, without significant differences between treatments. While there were more opioid-related side effects with BTDS treatment than with placebo, there were no serious adverse events. A total of 82% of patients chose to continue BTDS in a long-term open-label evaluation, in whom improvements in pain intensity, functionality and quality of life were sustained for up to six months without analgesic tolerance. CONCLUSION BTDS (5 microg/h to 20 microg/h) represents a new treatment option for initial opioid therapy in patients with chronic low back pain.

Waiting for Treatment for Chronic Pain – a Survey of Existing Benchmarks: Toward Establishing Evidence-Based Benchmarks for Medically Acceptable Waiting Times

As medical costs escalate, health care resources must be prioritized. In this context, there is an increasing need for benchmarks and best practices in wait time management. In December 2005, the Canadian Pain Society struck a Task Force to identify benchmarks for acceptable wait times for treatment of chronic pain. The task force mandate included a systematic review and survey to identify national or international wait time benchmarks for chronic pain, proposed or in use, along with a review of the evidence upon which they are based. An extensive systematic review of the literature and a survey of International Association for the Study of Pain Chapter Presidents and key informants has identified that there are no established benchmarks or guidelines for acceptable wait times for the treatment of chronic pain in use in the world. In countries with generic guidelines or wait time standards that apply to all outpatient clinics, there have been significant challenges faced by pain clinics in meeting the established targets. Important next steps are to ensure appropriate additional research and the establishment of international benchmarks or guidelines for acceptable wait times for the treatment of chronic pain. This will facilitate advocacy for improved access to appropriate care for people suffering from chronic pain around the world.

Guidelines for the use of cannabinoid compounds in chronic pain.

OBJECTIVE To provide clinicians with guidelines for the use of cannabinoid compounds in the treatment of chronic pain. METHODS Publications indexed from 1990 to 2005 in the National Library of Medicine Index Medicus were searched through PubMed. A consensus concerning these guidelines was achieved by the authors through review and discussion. RESULTS There are few clinical trials, case reports or case series concerning the use of cannabinoid compounds in the treatment of chronic pain. There are no randomized clinical trials examining the use of herbal cannabis in the treatment of chronic pain. CONCLUSIONS A practical approach to the treatment of chronic pain with cannabinoid compounds is presented. Specific suggestions about the off-label dosing of nabilone (Cesamet, Valeant Canada limitee/Limited) and dronabinol (Marinol, Solvay Pharma Inc, Canada) in the treatment of chronic pain are provided.

Offspring of Parents with Chronic Pain: A Systematic Review and Meta-Analysis of Pain, Health, Psychological, and Family Outcomes

Abstract Offspring of parents with chronic pain may be at risk for poorer outcomes than offspring of healthy parents. The objective of this research was to provide a comprehensive mixed-methods systematic synthesis of all available research on outcomes in offspring of parents with chronic pain. A systematic search was conducted for published articles in English examining pain, health, psychological, or family outcomes in offspring of parents with chronic pain. Fifty-nine eligible articles were identified (31 population-based, 25 clinical, 3 qualitative), including offspring from birth to adulthood and parents with varying chronic pain diagnoses (eg, mixed pain samples, arthritis). Meta-analysis was used to synthesize the results from population-based and clinical studies, while meta-ethnography was used to synthesize the results of qualitative studies. Increased pain complaints were found in offspring of mothers and of fathers with chronic pain and when both parents had chronic pain. Newborns of mothers with chronic pain were more likely to have adverse birth outcomes, including low birthweight, preterm delivery, caesarian section, intensive care admission, and mortality. Offspring of parents with chronic pain had greater externalizing and internalizing problems and poorer social competence and family outcomes. No significant differences were found on teacher-reported externalizing problems. The meta-ethnography identified 6 key concepts (developing independence, developing compassion, learning about health and coping, missing out, emotional health, and struggles communicating with parents). Across study designs, offspring of parents with chronic pain had poorer outcomes than other offspring, although the meta-ethnography noted some constructive impact of having a parent with chronic pain.

Catastrophizing, functional disability and pain reports in adults with chronic low back pain

OBJECTIVE: To test the hypothesis that subjective reports of pain severity, pain intensity and functional disability correlate positively with catastrophizing.