Patients With Chronic Pain Need Better Psychiatric Care

Psychiatrists are not often directly involved in the care of patients’ chronic pain. But psychiatric disorders are important determinants of the care that patients receive for chronic pain and the outcomes that they achieve with this care. If the care of chronic pain is to improve as urged in the new National Pain Strategy released by the U.S. Department of Health and Human Services, it will require greater attention to the psychiatric disorders common among patients with chronic pain.

The Institute of Medicine estimates that 100 million Americans suffer from chronic pain at a total cost of $600 billion. As clinicians have sought to address this challenge, the use of long-term opioid therapy for chronic pain has quadrupled in the last 15 years. The Centers for Disease Control and Prevention has described parallel increases among opioid sales, opioid abuse, and overdose deaths that it has called “the prescription opioid epidemic.” In 2013, there were over 16,000 deaths and 700,000 emergency department visits related to prescription opioids. Recent data suggest that opioid prescribing peaked around this time, but the more lethal co-prescribing of opioids and sedatives has not declined, while heroin use and mortality have grown.

Psychiatric disorders may play an important role in linking these opioid use, abuse, and overdose trends through a pervasive process of “adverse selection.” Adverse selection refers to the pairing of patients with mental health and substance use disorders who are at high risk for opioid adverse outcomes with higher-risk opioid regimens characterized by high opioid dose, long duration, and concurrent sedatives. Determining the value of prescribing opioid therapy for patients with psychiatric disorders is complicated by the fact that randomized, controlled trials of opioid efficacy for chronic pain conditions excluded patients with psychiatric comorbidities, even though these are highly prevalent in patients with chronic pain, especially patients on long-term, high-dose opioid therapy.

The causal relationship between chronic pain and various psychiatric disorders has been a matter of interest and research. Prospective studies have suggested that chronic pain can cause depression and that depression can also cause chronic pain. Psychological trauma and posttraumatic stress disorder also predispose individuals to pain, substance use, and mental illness. A bidirectional relationship likely underlies the strong association between pain and common mental disorders. This means that psychiatric disorders are not solely a reaction to chronic pain. They also predispose individuals to the development of chronic pain.

While patients with chronic pain usually acknowledge their distress, they often attribute it solely to their chronic pain. They often argue that reduction of their chronic pain will lead to relief of their distress. While this is true for acute pain, it is rarely true for chronic pain. In fact, there is emerging evidence that long-term opioid therapy increases the risk of both incident and recurrent major depression.

Although psychiatric disorders increase the likelihood that opioid therapy will be received, there is evidence that psychopathology reduces opioid analgesia. Depressed patients are more likely to overuse their opioids, because they use them to treat insomnia and stress. Depressed patients are more likely to be ambivalent about opioid therapy, simultaneously seeing opioids as helpful and wishing they could quit opioids. Past and current substance use disorders as well as current mental disorders are associated with opioid abuse or misuse in patients on chronic opioid therapy. Our best estimate is that 25 percent of patients on long-term opioid therapy will display significant opioid misuse and 10 percent will develop moderate to severe opioid use disorder.

Because opium has euphoric, sedating, and anxiolytic effects, it was widely recommended in the late 19th and early 20th centuries to treat melancholia, mania, and other forms of psychological distress. Recent opioid trials for depression or anxiety have been small, short, and poorly controlled and have not shown sustained benefit. We now know that the endogenous opioid system has diverse and complex effects on multiple forms of addiction, regulation of mood and stress response, social bond formation, appetitive behaviors, gonadal function, and cardiovascular and gastrointestinal function, among many others. Thus, long-term opioid treatment is not simply providing analgesia, but altering many neuroendocrine systems relevant to psychiatric disorders and psychiatric care.

Patients with chronic pain rarely see psychiatrists. It appears that opioids may be used in current clinical practice as the only psychiatric treatment for patients with chronic pain. This has been associated with high rates of opioid adverse events including misuse, abuse, and overdose. Moreover, there is little evidence of sustained benefit from opioid treatment of psychiatric disorders.

Since most long-term opioid therapy is prescribed in primary care settings, integration of psychiatrists into the primary care team offers the opportunity for improving the care of psychiatric disorders in patients with chronic pain. Multiple trials have demonstrated that collaborative care with care managers can improve pain and depression outcomes for patients with chronic pain. Pain-focused trials have not employed psychiatrists, though some have optimized antidepressant therapy and many have employed psychologists. Some depression-focused trials that employed psychiatrists have shown improvement in pain outcomes. As integrated psychiatric care is disseminated throughout primary care systems, it is important that it addresses the mental illness and substance use disorders commonly found in patients presenting for care of chronic pain. ■

The National Pain Strategy can be accessed here.