August 2015
David Craig, PharmD | Editor


The Journal of Pain Highlights

Journal of Pain cover

The following highlights summarize selected articles from The Journal of Pain (Volume 16, Issue 8, August 2015).

Estimates of Pain Prevalence and Severity in Adults: United States, 2012

Richard L. Nahin, National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD

Most American adults have experienced significant pain—temporary, chronic, minor, and severe—reports a new study prepared by the National Institutes of Health’s (NIH’s) National Center for Complementary and Integrative Health (NCCIH) and published in The Journal of Pain.

Based on data from the 2012 National Health Interview Survey (NHIS), the study estimates that, within a previous 3-month period, as many as 25 million adults had daily chronic pain and 23 million report having a lot of pain. Those with severe pain need and use more healthcare services and suffer greater disability than persons with less severe pain.

The annual NHIS study is conducted by the U.S. Centers for Disease Control and Prevention (CDC) and surveys tens of thousands of Americans about their overall health and illnesses. The 2012 NHIS study asked participants about the frequency and intensity of pain experienced in the previous 3 months.

The findings also showed that half of individuals with the most severe pain still rated their overall health as good or better and there were associations between pain severity and race, ethnicity, language preference, gender, and age. Women, older individuals, and non-Hispanics were more likely to report any pain, but Asians were less likely. Also, the impact of gender on pain varied by race and ethnicity.

In an NIH news release, Richard L. Nahin, PhD MPH, lead epidemiologist for NCCIH and author of the analysis said, “This report begins to answer calls for better national data on the nature and extent of the pain problem. The experience of pain is subjective. It’s not surprising then that the data show varied responses to pain even in those with similar levels of pain. Continuing analyses of these data may help identify subpopulations that would benefit from additional pain treatment options.”

Effects of Milnacipran on Clinical Pain and Hyperalgesia of Patients with Fibromyalgia: Results of a 6-Week Randomized Trial

Adam T. Hirsh, Nicole A. Hollingshead, Leslie Ashburn-Nardo, Kurt Kroenke; Department of Psychology, Indiana University–Purdue University Indianapolis, Indianapolis, IN; VA Health Services Research and Development Center of Excellence on Implementing Evidence-Based Practice, Roudebush VA Medical Center, Indianapolis, IN

Results of a 6-week trial, reported in The Journal of Pain, showed efficacy of the drug milnacipan was no different from placebo for clinical pain reduction in fibromyalgia patients given mechanic and heat pain stimuli.

Researchers from the University of Florida sought to apply quantitative sensory testing (QST) to check the effects of milnacipan, a serotonin-norepinephrine reuptake inhibitor approved by the U.S. Food and Drug Administration for treatment of fibromyalgia pain, on spinal and supraspinal pain pathways. Because the chronic musculoskeletal pain associated with fibromyalgia is closely linked with hyperalgesia, the researchers hypothesized that milnacipran would reduce not only clinical pain but also mechanical and heat hyperalgesia in a sample of 46 people with fibromyalgia. Study participants were recruited from the community and fibromyalgia support groups.

Results showed the fibromyalgia patients reported significant reductions of clinical pain and mechanical and heat pain sensitivity. These improvements, however, were nonspecific and unrelated to a milnacipran effect. The authors noted that the evidence suggests that milnacipran may not be effective for improving the well-known mechanical and heat hyperalgesia in patients with fibromyalgia.

PAIN Highlights

Pain Medicine Cover

The following highlights summarize selected articles from PAIN (Volume 156, Issue 8, August 2015).

Chronic Widespread Pain: Clinical Comorbidities and Psychological Correlates

Andrea Burri, Soshiro Ogata, Jelle Vehof, and Frances Williams; Department of Psychology, University of Zurich, Zurich, Switzerland; Department of Twin Research, King’s College London, London, UK; Department of Health Promotion Science, Osaka University Graduate School of Medicine, Suita, Osaka, Japan; Departments of Ophthalmology and Epidemiology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands

In this study, investigators aimed to clarify the etiological structure underlying chronic widespread pain (CWP) by examining the covariation between CWP and previously reported psychiatric comorbidities such as depression and psychoaffective correlates (anxiety, emotional instability, and emotional intelligence) and the genetic and environmental components in TwinsUK, a large sample of unselected British female twin volunteers with a mean age of 56.6 years.

Investigators demonstrated that two genetic factors and one environmental factor explain the relationship between CWP, depression, anxiety sensitivity, emotional instability, and emotional intelligence through two common latent traits. Although one genetic factor loaded on both latent traits, they identified a second genetic factor loading onto CWP and depression alone. These findings provide important insights into the etiologic nature of CWP and its clinical comorbidity, depression, on the role of potential psychoaffective risk factors and clinical comorbidities.

Apart from a genetic influence, investigators found no evidence of environmental influence shared by siblings on individual differences in CWP. Instead, environmental influences that were important involved entirely nonshared factors, and their effect size was similar to the genetic effects. In other words, genes and environmental stressors and factors seem to be equally important for the development and maintenance of CWP.

Overall, these results support previous findings that demonstrated pain reporting is intimately linked to mood (in particular, depression) and that emotional regulation shares a common genetic basis with CWP and depression, highlighting further the complex view of the multifactorial pathogenesis of pain. These findings provide promising starting points for interventional strategies and protocols in which the role of cognitive and emotional restructuring might be addressed.

Sleep and Pain Sensitivity in Adults

Børge Sivertsen, Tea Lallukka, Keith J. Petrie, Olöf Anna Steingrímsóttir, Audun Stubhaug, and Christopher Sivert Nielsen; Division of Mental Health, Norwegian Institute of Public Health, Bergen and Oslo, Norway; Regional Centre for Child and Youth Mental Health and Child Welfare, Uni Research Health, Bergen, Norway; Department of Psychiatry, Helse Fonna HF, Haugesund, Norway; Finnish Institute of Occupational Health, Helsinki, Finland; Department of Public Health, University of Helsinki, Helsinki, Finland; Department of Psychological Medicine, University of Auckland, Auckland, New Zealand; Department of Health Statistics, Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway; Department of Pain Management and Research, Oslo University Hospital, Oslo; Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo

Although there is a strong relationship between pain and sleep (insomnia increases the likelihood and severity of clinical pain), it is not clear why this is the case. Specifically, it is not known whether insomnia increases pain by exacerbating conditions that cause pain (for example, through immunological changes causing muscle and joint soreness) or whether poor sleep quality affects pain processing more directly by sensitizing peripheral nociceptors or by affecting central inhibitory and facilitating mechanisms, causing a state of generalized hyperalgesia. The aims of this population-based study were to determine the association between pain sensitivity and a range of sleep parameters in a large population-based sample and to further investigate the relationship between pain and sleep by examining the joint or synergistic association of insomnia and chronic pain on pain sensitivity. The mean age of the 10,412 participants was 57.5, and the sample included more women (53.4%) than men (46.6%).

All sleep parameters were significantly associated with reduced pain tolerance. Both the frequency and severity of insomnia, in addition to sleep onset problems and sleep efficiency, were associated with pain sensitivity in a dose-response manner. Most associations remained significant in the fully adjusted models. Investigators also found a synergistic interaction effect on pain tolerance when combining insomnia and chronic pain.

Because comorbid sleep problems and pain have been linked to elevated disability, the need to improve sleep among patients with chronic pain, and vice versa, is clear. Both pharmacological and cognitive behavioral therapy (CBT) interventions for insomnia and pain interactions have been thoroughly investigated. A CBT-based approach addressing both pain and sleep was found effective in previous studies. As such, future research should focus on examining low-threshold interventions of comorbid sleep and pain; Internet-based self-help interventions have shown promising results in treating both conditions individually. More research is needed to examine how sleep problems may alter dopamine functioning and how this may ultimately influence pain sensitivity.



Pain Medicine Highlights


The following highlights summarize selected articles from Pain Medicine (Volume 16, Issue 7, July 2015).

Unresolved Pain Interference Among Colorectal Cancer Survivors: Implications for Patient Care and Outcomes

Kelly Kenzik, Maria Pisu, Shelley A. Johns, Tamara Baker, Robert A. Oster, Elizabeth Kvale, Mona N. Fouad, and Michelle Y. Martin; Center for Outcomes and Effectiveness Research and Education, University of Alabama at Birmingham, School of Medicine, MT617, Birmingham; Division of Preventive Medicine, University of Alabama at Birmingham School of Medicine, MT617, Birmingham, AL; Division of General Internal Medicine and Geriatrics, Indiana University, School of Medicine, Indianapolis, IN; Department of Psychology, University of Kansas, College of Liberal Arts and Science, Lawrence, KS; University of Alabama at Birmingham, School of Medicine, MT617, Birmingham, AL

The prevalence of pain among cancer survivors ranges between 20% and more than 60%, making cancer a priority topic in the Institute of Medicine’s (IOM) call for addressing pain in the United States. The prevalence, duration, and intensity of pain can vary depending on several factors, including cancer type. For example, survivors of colorectal cancer often report less pain intensity than survivors of head and neck, lung, and breast cancers.

Factors predictive of pain intensity such as age, gender, race, treatment, and comorbidities are also associated with pain interference (PI). Comorbidities are important because cancer survivors are less likely to adequately care for and manage comorbid conditions such as diabetes. Also, when compared to breast and prostate cancer survivors, colorectal cancer (CRC) survivors are less likely to manage their comorbid conditions.

The purpose of this study was to address research gaps regarding CRC-related PI. Investigators worked to describe the prevalence of PI among a racially/ethnically diverse group of patients with CRC during the initial phase of care and at posttreatment follow-up, identify sociodemographic and clinical variables associated with PI according to a biopsychosocial model, and examine the relationship between PI and changes in job status.

One in four CRC survivors reported moderate/high PI during the initial phase of care and approximately 1 year later. Consistent with the biopsychosocial model of pain, multiple factors contributed to a higher likelihood of PI during the initial phase of care, including being female and younger, having comorbidities and depression problems, and receiving chemotherapy and radiation. These same factors were associated with reporting PI at posttreatment follow-up.

Among survivors who reported PI during the initial phase of care, however, a subset of comorbidities including pulmonary disease and heart failure predicted equivalent or increased PI 1 year postdiagnosis. The impact of unresolved PI is substantial. Survivors employed during the initial phase of care were more likely to report not having a job posttreatment if they continued to experience PI.

Addressing chronic comorbidities that are likely contributing to the source of pain, managing expectations for recovery, discussing pain medication use, and identifying therapies for treating pain-related functional problems and/or psychological conditions are important considerations to ensure a comprehensive approach to PI reduction.

Attitudes and Beliefs of Working and Work-Disabled People with Chronic Pain Prescribed Long-Term Opioids

James P. Robinson, Elizabeth J. Dansie, Hilary D. Wilson, Suzanne Rapp, and Dennis C. Turk; Department of Rehabilitation Medicine, University of Washington, Seattle, WA; Evidera, Outcomes Research, Seattle, WA; Department of Anesthesiology and Pain Medicine and Center for Pain Research on Impact, Measurement, and Effectiveness (C-PRIME), University of Washington, Seattle, WA

The appropriateness of long-term opioid therapy (LOT) to address chronic noncancer pain has received substantial attention from researchers and policy makers. Although a majority of patients with chronic pain who take prescribed opioids continue to report high levels of pain, they rate their medication as beneficial and even essential. This study was designed to provide insight into the attitudes and behaviors of nonabusing patients taking LOT through administration of a detailed questionnaire that explored patients’ early experiences with LOT, their perceptions regarding the benefits they derive from opioids in several domains, their concerns about side effects from opioids, and their interactions with family members and physicians regarding their LOT.

Investigators used “work status” as a proxy for the ability of patients taking LOT to function despite their pain and opioid prescriptions. They hypothesized that working users of LOT would differ from work-disabled users in functional impairment and emotional functioning. The research goal was not to provide definitive answers, but to identify issues that could be explored more rigorously in future studies.

Working and work-disabled participants did not differ significantly in gender, education level, or average opioid dose. Work-disabled participants had lower incomes than working participants, were younger, stated that their pain had started at an earlier age, and reported higher average pain levels.

Work-disabled participants expressed stronger agreement with statements such as, “Opioids help me feel less depressed,” and “Opioids help me relax and reduce my stress level.” They were more likely than working participants to take an opioid dose to prevent anticipated future pain or to take a dose before visiting family or friends. Physicians rated working patients as less disabled, as managing their pain better, and as being helped more by their opioids.

Overall, patients assigned positive ratings for their opioid therapy, stating that opioids relieved their pain, and identified several other opioid-related benefits. They contended that opioids provided some control over their pain; were effective in permitting them to function, engage in daily activities, and work at a job or at home; and helped them be less dependent on others.