[Commentary] CAN ONE BE AN EXPERT IN ADDICTION MEDICINE WITHOUT EXPERTISE IN PAIN MANAGEMENT?

Abstract

The paper by Caldeiro et al.[1] in this issue notes the conundrum in which patients with pain and addiction find themselves: 'pain complaints are difficult to address until addiction is treated, but addiction treatment is compromised by persistent pain'. Patients share this conundrum with their health-care providers. We see this Catch 22 situation in the hospital, medical and mental health clinics and addiction treatment programs, yet the prevalence and outcomes of these co-occurring, biologically linked conditions has been described relatively recently in the medical literature. Furthermore, our clinical management is lacking in evidence-based guidance. Caldeiro et al. demonstrate, among 582 patients with non-opioid substance dependence in the Veterans Administration health-care system, that pain is common and it matters. Patients with persistent pain have worse medical and substance use outcomes and use more resources. This study confirms and extends earlier work [2,3] by demonstrating this relationship in addictions other than opioid dependence. A previous study among patients in methadone maintenance and short-term residential treatment programs found the prevalence of chronic severe pain to be 37% and 24%, respectively, and use of illicit drugs to treat their pain similarly common (34% and 51%, respectively). Characterizing the overlap between pain and addiction beyond opioids is important, as it is now clear that the relationship of pain and addiction is more complicated than one family of opioid receptors (e.g. mu). For example, pre-clinical research demonstrates that there is substantial overlap among the opioid and cannabinoid receptor systems in modulating analgesia both in inflammatory and neuropathic pain conditions [4]. Clinical trials of cannabinoid agonists show promise for chronic neuropathic pain [5,6]. Alcohol is a weak analgesic. Cocaine, while not a known analgesic in humans, was first used clinically as a topical anesthetic in the 1880s. The abuse of both has been associated with prescription opioid abuse among patients with chronic pain [7,8]. Do these associations between pain and different addictions represent a single phenomenon mediated by a final common neurochemical pathway, or are they driven separately by each substance, pain source and individual's vulnerability? Is it best to couple known treatments of addiction and pain, or are there better therapies targeted specifically to patients with both conditions? Future research will address these questions, providing a more complete understanding of the interplay between pain and addiction. The treatment of chronic pain with opioids has a modest evidence base [9–11]. Most studies have follow-up periods of less than 6 months, involve highly selected populations and do not include patients with co-occurring addiction. Intervention studies targeted to individuals with both addictions and chronic pain are rare. The management recommendations in the Principles of Addiction Medicine[12] repeat the approach and clinical guidelines developed in the early 1990s for the management of cancer pain by the Agency for Health Care Policy Research. These guidelines have not been examined specifically in patients with underlying addictions with chronic non-cancer pain. The evidence we have to address these interwoven conditions is based largely on studies focused upon these conditions in isolation. It is time for rigorously designed longitudinal research of behavioral and pharmacological treatments focused upon groups with addictions and overlapping chronic pain. Despite the ever-present need for future research, the implications of these authors' findings speak to the need for present action. Pain assessments and efforts to address painful conditions adequately should be explored, as noted by Caldeiro et al. in their discussion. Models of care that best achieve such assessment and appropriate relief will improve current clinical treatment in both substance use and medical settings. Beyond improved diagnostic tools and treatment models, these findings call for physicians who practice addiction medicine to become expert in the evaluation and treatment of pain. The fact that pain is present in more than half our patients with addiction, even in those with non-opioid addictions, begs the question: can one be an expert in addiction medicine without expertise in pain management? Despite the current modest evidence base, evaluation and treatment of pain in addicted patients merits a place among the core competencies in addiction medicine. The core competencies for a subspecialty in addiction psychiatry call for addiction psychiatrists to demonstrate knowledge of the evaluation and consultation on chronic pain [13]. As it considers the content of a certification examination, the new American Board of Addiction Medicine (ABAM) should include pain assessment and management as one of its core subjects. Such a mandate will support and propel the drive for stro