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14 Articles in Volume 12, Issue #2
Chronic Pain in the Elderly: Special Challenges
Chronic Pain School
Diagnosis and Management Of Myofascial Pain Syndrome
ECG Screening Prior to Initiating Methadone: Is it Really Necessary?
HCG and Testosterone
How to Manage Unmotivated Pain Patients
March 2012 Pain Research Updates
Methadone for Pain Management
PPM Editorial Board Discusses Methadone Prescription Safety Measures
PPM Launches Online Opioid Calculator
Spontaneous Low Back Pain, Radiculopathy, And Weakness in a 28-Year-Old
Tapering a Patient Off Opioids
The Comorbidity of Chronic Pain and Mental Health Disorders: How to Manage Both
What Are Best Safety Practices For Use of Methadone In the Treatment Of Pain?

The Comorbidity of Chronic Pain and Mental Health Disorders: How to Manage Both

Part 3 of a three-part series examines the interdisciplinary treatment of comorbid pain and mental health disorders.

One of the most successful treatment models for comorbid pain and mental health disorders is a program based on the biopsychosocial model, which takes into account physical, mental health, and social issues. There is a great deal of evidence showing the effectiveness of this treatment model for musculoskeletal pain, temporomandibular disorder (TMD), headaches, and widespread pain and fibromyalgia.1

Functional Restoration
One of the earliest biopsychosocial treatment programs—functional restoration—was designed to address the problems encountered by patients with chronic occupational musculoskeletal disorders. Functional restoration is implemented by an interdisciplinary team of healthcare professionals operating together to achieve a unified treatment plan that is individualized to patient needs. The team is led by a supervising physician who coordinates patient care with an emphasis on return to function.

There are two main components to a functional restoration program: a quantitatively directed exercise program and a multimodal disability management program. The quantitatively directed exercise program is based on the sports medicine principle of working through pain rather than avoiding it. Physical and occupational therapists work with patients to reactivate deconditioned muscles, joints, and ligaments using active exercise treatments rather than passive pain-reducing modalities.2 The multimodal disability management program addresses the psychosocial issues of the patient with chronic pain. Mental health professionals lead group and individual counseling sessions of cognitive-behavioral therapy based on a crisis intervention model. The case management department assists the patient in navigating the workers’ compensation and disability insurance systems and also assists with vocational reintegration so patients can successfully return to employment after treatment.2

A great many studies have demonstrated the effectiveness of interdisciplinary rehabilitation for the treatment of chronic spinal and musculoskeletal pain.3-16 The majority of interdisciplinary rehabilitation studies have focused on patients with chronic spinal and musculoskeletal pain (disabled for more than 4 months), but the functional restoration model also has shown success in treating acute and subacute musculoskeletal pain.17

The success of interdisciplinary rehabilitation in the treatment of musculoskeletal pain has prompted its expansion into the treatment of other pain conditions. In the treatment of headaches, interdisciplinary programs usually include stress management training, relaxation exercises, biofeedback treatments, and education about headache triggers and medication compliance.18-20 In some cases, physical therapy and exercise are part of the treatment program, especially in tension-type headaches. In addition, decreases in depressive and anxious symptoms have been noted, and patients also may show improvements in absences from work and headache-related disability.18-22

In the management of TMD, interdisciplinary programs usually include cognitive-behavioral skill training, biofeedback, stress education, and relaxation training. Patients demonstrate long-lasting improvements in pain intensity, pain-related disability, and mandibular function.23-25 A systematic review of TMD treatment programs also found evidence for the effectiveness of exercise, postural training, relaxation, and biofeedback in the treatment of TMD.26

In addition, functional restoration programs have been applied to conditions such as chronic widespread pain and fibromyalgia, with results similar to those found in musculoskeletal pain patients.27 Other interdisciplinary programs also have shown success in treating fibromyalgia.28,29 Finally, interdisciplinary programs have shown some preliminary success in treating neuropathic pain conditions such as nerve injury and neuropathy,30,31 but further study is needed in this area.

Overall, treatments for chronic pain and mental health disorders based on the biopsychosocial model have shown consistently high success rates for a variety of conditions.32

Pharmacotherapy
The high comorbidity between chronic pain and psychiatric disorders often necessitates the incorporation of psychotropic medication in chronic pain management. Additionally, the use of psychotropic medications is reinforced by their effectiveness as adjuvant analgesics. Psychotropic medication also modifies opioid doses, thus preventing, in part, dependency.

Selecting the Right Medication
Specific issues that need to be considered when prescribing any medication are:

  • Cause of patients’ chronic pain and their complaints (see Table 1)
  • Comorbidity of chronic pain with other illnesses and/or psychiatric condition
  • History of patients’ medication pertinent to complaints, including abuse, dependence, compliance, and side effects

Opioid Analgesics
Opioids are used as a second-line treatment for moderate to severe noncancer pain when patients do not respond to acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs), experience pain-related functional impairment, or have diminished quality of life (see Table 2, page 63).33-36 Before prescribing such medications, a thorough assessment of risk for interaction between potential opioid and concurrent psychiatric medication, as well as drug abuse history, must be diligently conducted.37 Noble et al conducted a meta-analysis of long-term opioid management of chronic noncancer pain. Many patients discontinued opioid treatment because of adverse effects (8.9% to 22.9%) or insufficient pain relief (5.8% to 10.3%) depending on mode of consumption (oral, transdermal, or intrathecal).38 Long-term opioid medication, with various analgesic effects, results in pain relief. Inconclusive results were found for the effect of opioid medication on quality of life and functioning. For neuropathic pain, opioids were reported to be more effective than placebo in an intermediate-term study.39

Opioids may be classified as having weak (eg, codeine, hydrocodone, and oxycodone) or strong (eg, morphine, fentanyl, and hydromorphone) analgesic properties; thus, the type of opioid prescribed depends on the patient’s pain intensity. There is evidence of oxymorphone efficacy in controlling and reducing pain compared with placebo in chronic low back pain.40,41 Propoxyphene and dextropropoxyphene are not recommended because of their low therapeutic-to-toxicity ratios.42

Antidepressants
The effectiveness of antidepressants in treating neuropathic and non-neuropathic pain contributes to the popularity of these drugs in pain management.43 The mood-elevating effects of antidepressants are useful because people suffering from chronic pain often experience depressed mood or even a major mood disorder. Antidepressants, especially serotonin-norepinephrine reuptake inhibitors (SNRIs) and selective serotonin reuptake inhibitors (SSRIs), also are effective in treating anxiety disorders. Over the years, more clinical research has reported the analgesic effect of antidepressants, independent from their mood alterating effects (see Table 3, page 64).

Antidepressants may be classified into several general types: tricyclic antidepressants (TCAs), SSRIs, SNRIs, and monoamine oxidase inhibitors (MAOIs). MAOIs are rarely prescribed today because of their side effects, such as fatal hypertensive crises resulting from interactions between these drugs, tyramine-containing foods, opioids, and other psychotropic medications.44,45

TCAs are commonly used to treat psychiatric disorders and also have the longest track record of use in the treatment of multiple pain conditions. Neuropathic pain responds better than nociceptive pain to TCAs; however, TCAs may be effective in treating nociceptive pain comorbid with depression.46 TCAs also have shown efficacy in treating low back pain, but not necessarily in relieving arm pain.47,48 A recent meta-analysis of systematic reviews suggested that TCAs may be effective for treatment of pain in TMD. However, the heterogeneity of results makes it difficult to draw definite conclusions.49 The undecided mechanism underlying TMD pain also is a limitation in studying TMD pharmacology. A systematic review assigned a Level B recommendation of scientific evidence for using TCAs in treating TMD.50

TCAs and SNRIs are the first-line medications for neuropathic pain.51 TCAs have been found to be useful in the treatment of fibromyalgia. However, SNRIs are more popular because they have fewer adverse side effects.52 The side effects of TCAs include sedation, dry mouth, blurred vision, urinary retention, constipation, and postural hypotension.45 SSRIs may yield effective results for patients experiencing adverse side effects from TCAs, even though there is limited evidence regarding the effectiveness of SSRIs in the treatment of neuropathic pain.51 Antidepressants also can replace anxiolytics (anti-anxiety agents) in treating chronic pain comorbid with anxiety disorder.

Theoretically, SNRIs are thought to be more effective in treating chronic pain because they inhibit both serotonin and norepinephrine. This assumption is validated by research findings, especially regarding the effectiveness of SNRIs in treating neuropathic pain and fibromyalgia.43,51 Both SNRIs (eg, duloxetine [Cymbalta] and milnacipran [Savella]) and SSRIs (eg, fluoxetine and paroxetine) have been shown to provide pain relief and improve function and quality of life in patients with fibromyalgia.53 Venlafaxine, duloxetine, and milnacipran also have been found to reduce pain intensity and increase function compared with placebo, resulting in better sleep and decreased fatigue.54-57 One study found venlafaxine XR to reduce the number of days with headache compared with placebo.58 However, a meta-analysis showed that SSRIs are not effective in reducing tension-type headaches or migraines.59

Anticonvulsant Drugs
Anticonvulsant drugs are useful for treating neuropathic pain60 as well as ameliorating mood swings. Anticonvulsants have mood-stabilizing effects and therefore are useful in treating pain comorbid with bipolar disorder, schizoaffective disorder, and impulsivity arising from dementia (see Table 4).61,62 Gabapentin (Neurontin and others) has shown benefits for patients suffering from panic attack and social anxiety disorder, whereas pregabalin (Lyrica) is effective in treating general anxiety disorder.61 Effective analgesia is achieved from the combination of gabapentin and morphine, each in a lower dose than when prescribed as a single agent.63

Sedatives, Tranquilizers, And Anxiolytics
Sleep disturbance is common in patients with chronic pain with or without psychiatric comorbidities. Benzodiazepines usually are prescribed for sleep disturbance because of their sedating and tranquilizing effects. However, the use of benzodiazepines is secondary to the use of a sedating antidepressant, such as amitriptyline, doxepin, mirtazapine, and trazodone, in patients with comorbid mental illness.45 Furthermore, the use of benzodiazepines also can result in the development of dependence, especially when patients also are prescribed morphine or other opioid drugs, because of drug–drug interactions.64 Clinicians always should use caution when prescribing opioids together with benzodiazepines.

Therapeutic Outcomes
When assessing and treating these comorbid pain and psychiatric conditions, the final piece of important information comes from the evaluation of treatment outcomes. Issues such as treatment completion, response to treatment, and long-term outcomes are of interest in this endeavor.

Program Completion
The completion of a treatment program is an important outcome variable for this comorbid population. Findings from one recent study revealed that patients who were opioid dependent were 1.5 times more likely to fail to complete an interdisciplinary rehabilitation program and patients diagnosed with a socially problematic Cluster B personality disorder were 1.6 times more likely to drop out compared to controls.65 Although some researchers have reported no differences between those who “drop out” and those who complete treatment,66,67 a major study did find significant socioeconomic differences in outcomes such as returning to work.68

Treatment Responsiveness
Treatment responsiveness is commonly assessed using the array of self-report measures reviewed in the November/December 2011 issue of Practical Pain Management. Patient self-reported pain is probably the most commonly assessed outcome in chronic pain research, although it can be assessed in a variety of ways. In general, those with major depressive disorder (MDD) or an anxiety disorder have the poorest pain outcomes67,69,70; although Karp et al found that with duloxetine treatment, 93% of those with MDD and chronic low back pain had decreased their pain by 30% or more.71 By contrast, Holroyd and colleagues did not find similar results in a chronic tension-type headache (CTTH) population: The presence of a psychiatric disorder did not influence patients’ scores on the Headache Index.21

As a general trend, those with anxiety or mood disorders often have higher rates of disability than those with other disorders or those without the presence of a psychiatric disorder. For instance, Brown and investigators found that those with both anxiety and depression had the greatest number of disability days over 4 weeks, as well as the highest levels of disability (as measured by the Sheehan Disability Scale).72 It also has been reported that patients with a combination of anxiety and depression fare worse than those with only one psychiatric diagnosis.67,73,74 Additionally, in a cervical surgery population, Taylor et al found that those with any psychiatric disorder were more likely to be disabled than those who did not have a diagnosis.75

Depression remission or reduction in depressive symptoms is another common outcome measure assessed in this population. Generally, those with MDD and a higher severity of chronic pain were less likely to achieve depression remission with antidepressant treatment.71-76 However, those with a pain disorder (PD) or generalized anxiety disorder (GAD) also continued to have depressive symptoms in a case management program.77 Teh and colleagues found that those with higher pain severity, as well as either comorbid GAD or PD, had higher ratings of anxiety and less anxiety remission when treated with case management.77 However, treatment with antidepressants and a self-management training program have helped to decrease anxiety in patients with comorbid pain and MDD.73

Long-Term Outcomes
The most common long-term outcomes examined are patient work status and healthcare use. Several studies have found that patients with MDD are employed less frequently.69 In addition, there is evidence supporting that, following cervical surgery, the presence of any psychiatric disorder predicts lower return to work rates.75 Patients with opioid dependence or a paranoid personality disorder had significantly lower rates of return to work and work retention than those who were not diagnosed with a disorder.78

Healthcare use also seems to be strongly affected by the presence of a psychiatric disorder, most specifically GAD. Those with GAD have more visits to the doctor and the emergency department,67 and this trend continues whether the patient with GAD has an additional comorbidity such as MDD or a personality disorder.77,79 Surprisingly, it also has been reported that patients without depression, on average, visited a physician nearly twice as often over a 12-month period relative to their depressed counterparts.69 Less surprising was that those diagnosed with opioid dependence were twice as likely to seek a new healthcare provider, and those with post-traumatic stress disorder (PTSD) were 4 times as likely to have a new surgery.78 However, in a comorbid depression/musculoskeletal pain population, there were no differences between the group receiving standard medical care and those receiving antidepressants and self-management training.73 Other long-term outcomes include the continuation of depression remission. In a group of patients with chronic low back pain, the rate of MDD was reduced from 70% at pretreatment to 30% 6 months after completion of a functional restoration program.80

Conclusion
The next area of important clinical research appears to be incorporating not only a biopsychosocial approach into the treatment of chronic pain, but also earlier intervention at the acute stage. On the basis of past research conducted in patients with comorbid chronic pain and psychiatric disorders, one would assume that such comorbidity may be treated with equal success during early intervention programs.

Correction from May 2012
Regarding the article in the March 2012 issue of Practical Pain Management titled, “The Comorbidity of Chronic Pain and Mental Health Disorders: How to Manage Both,”1 I’d like to clarify one statement: The authors stated that oxycodone and hydrocodone are weak opioids, whereas morphine is a strong opioid. Actually, all three are considered strong opioids. In fact, oxycodone is about 1.5 times as strong as morphine, and hydrocodone is a little weaker, but still stronger than morphine. It’s important to know this in order to correctly calculate conversion among these opioids.

Jennifer Schneider, MD, PhD
Internal Medicine, Addiction Medicine, and Pain Management
Tucson, Arizona

Last updated on: March 29, 2019
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