Chronic pain and addiction: worry about the worrier

KEYWORDS:

• Chronic pain
• addiction
• substance use disorder
• anxiety
• catastrophizing

The overwhelming majority of the 5–8 million Americans with chronic non-malignant pain and treated with opioid therapy appreciate improvements in pain severity, functionality and quality of life. However, approximately 8–10% of these patients will develop an opioid use disorder (1), and in some cases, move to illicit opioid use bringing the worrisome risks of fentanyl exposure and overdose. These rates of 8–10% mirror those for substance use disorder in the general population (2), but the ongoing opioid crisis in this country and the role prescribed opioids have played in this crisis underscore the need for prescribers to consider a patient’s risk for developing addiction prior to or over the course of opioid pharmacotherapy.

Despite valid concerns about the chilling effects of the 2016 CDC Guideline for Prescribing Opioids for Chronic Pain (3) on opioid prescribing for patients with pain, the Guideline got right the recommendation that prescribers screen patients for their risk of developing an opioid use disorder prior to initiating opioid therapy. This screening includes the assessment of known risk factors for addiction, including a personal history of addiction, a family history of addiction, psychiatric comorbidity, and a history of adverse childhood experiences, as well as the use of screening tools such as the recently validated Opioid Risk Tool-revised (4). As with prescription of any medication, it is incumbent upon the clinician to ensure that the patient is not at risk for an untoward response; development of a substance use disorder is a particularly worrisome response in the case of opioid therapy.

Four of the papers in this issue of the American Journal of Drug and Alcohol Abuse describe a relatively novel but increasingly appreciated risk factor for the development of opioid or alcohol use disorder in patients with chronic pain, which can be broadly conceptualized as being a “pain worrier”, or an individual who demonstrates high levels of pain-specific fear or affective distress. Variously referred to as pain catastrophizing (5), pain-related anxiety (6), anxiety sensitivity (7), and psychophysiologic pain reactivity (8), these investigators provide evidence that chronic pain patients in the community with higher levels of this construct not only report more severe pain, but also more problematic opioid and alcohol use, and for those receiving treatment for a substance use disorder, more drug craving and exaggerated autonomic responses to a painful stimulus.

Specifically, Zale and colleagues (6) show that male chronic pain patients who score highly on a measure of pain-related anxiety engage in more problematic alcohol consumption and report higher levels of alcohol dependence. Conceptualizing this tendency to worry about pain as anxiety related to physical sensations, Rogers and colleagues (7) found that chronic pain patients with greater anxiety sensitivity were more likely to report misusing their prescribed opioids and higher levels of opioid dependence. Although neither study provides evidence of an association between pain anxiety and opioid use disorder, the tendency to misuse or abuse substances among those with more anxiety is evident, theoretically putting them at higher risk for developing addiction. Notably, in both studies, pain-related anxiety is a stronger predictor of alcohol and opioid misuse than is the severity of the chronic pain, implying that substance use is motivated by a desire to treat affective anxiety as opposed to physical pain.

Supporting the relationship between pain-related anxiety and opioid use disorder are the two studies conducted in chronic pain patients with a history of addiction. Kneeland and colleagues (5) show that pain catastrophizing, or the tendency to interpret pain as harmful, intolerable or uncontrollable, is associated with higher levels of craving and more affective distress in a sample of patients receiving treatment in an inpatient detoxification unit. Focusing on psychophysiological indicators of anxiety (i.e., heart rate, galvanic skin response, temperature, muscle tension), Wachholtz and colleagues (8) found that patients with chronic pain and a history of an opioid use disorder demonstrated a greater autonomic stress response to an experimental painful stimulus than did opioid-naïve chronic pain patients. Interestingly, chronic pain patients on methadone or buprenorphine therapy did not evidence this pain-related stress response, suggesting that the opioid therapy was in fact effective in treating this pain-related anxiety.

Whether this affective distress makes the chronic pain “feel worse” and thereby drives opioid use, or stepped-up opioid use reflects a coping mechanism for the uncomfortable feelings, cannot be determined in these cross-sectional studies and both mechanisms have been suggested. Similarly, the role of pain-related anxiety as a predictor vs. a correlate of opioid use disorder cannot be established without prospective evaluations, although the finding of the association in patients who misuse (but are not necessarily addicted to) opioids (7) and in patients with opioid use disorder in drug-free recovery (8) suggest that it is more of a pre-existing trait than a state, and therefore can be considered a risk factor.

Albeit trait-like, the authors remind us that this pain-specific anxiety is amenable to intervention. Cognitive behavioral therapy integrating cognitive restructuring, stress reduction techniques and enhanced coping skills have been demonstrated to decrease pain catastrophizing and pain-related anxiety; the fact that these approaches are also a staple of effective addiction treatment belies their similitude. Notably, pain catastrophizing has also been linked to poorer surgical outcomes, predicting the development of chronic post-surgical pain and long-term opioid use (9), thus cognitive behavioral interventions to address it prior to planned surgeries are the subject of current evaluations. It is understood that the identification and treatment of “pain worriers” in both chronic and acute pain contexts can improve pain outcomes; these four papers build upon accumulating evidence that the same could serve as another tool in our risk assessment and intervention toolbox to prevent opioid use disorder from becoming an outcome of opioid therapy for chronic pain.

Additional information

Funding

This work was supported by the Van Ameringen Foundation [Endowed Chair].