What Principles Should Guide the Prescribing of Opioids for Noncancer Pain?

Introduction and Scope of the Problem

Over the past 30 years, chronic pain and opioid use have dominated the headlines, both in popular news sources and in medical journals. Chronic pain impacted the lives of more than 125 million adults in 2012, and its $635 billion economic impact on the U.S. health care system is greater than diabetes, heart disease, and cancer combined. Meanwhile, the United States is in the midst of one of the great public health crises of modern times: the opioid epidemic. For the first time since the invention of the motor vehicle, an adult in the United States is more likely to die from an opioid overdose than from a motor vehicle collision. Vigorous research, education, and legislative efforts had helped reverse the course briefly, but a generational challenge to our health care system, the COVID-19 pandemic, has led to a resurgence of the opioid overdose crisis. These findings have important implications for the practice of opioid prescribing in the management of nonmalignant pain syndromes. This chapter reviews the history, current research, and available clinical practice guidelines for opioid utilization in noncancer pain in this context.

Chronic noncancer pain (CNCP) presents a unique challenge to the health care system on multiple levels, and the mainstream public perception of the utility of opioids continues to lag well behind our current understanding of where these agents fit into evidence-based clinical practice. Patients with chronic pain suffer from inadequate expectations and negative social and clinician attitudes regarding CNCP. Moreover, Black, Indigenous, and People of Color face the ongoing challenge of systematic racism: they have less access to pain medicines, expert pain medicine clinicians, and interprofessional pain management teams. Effective and safe treatment of CNCP is an intensive endeavor that requires training, time, and clinical resources. However, clinicians face a lack of training, funding, and resources to create robust interprofessional pain management teams, in addition to the ever-present challenge of finding the balance between relief of patient suffering and ensuring safety and long-term well-being.

This lack of access to effective chronic pain care within our health care system, combined with an appreciation for palliative care's interdisciplinary “whole-person” approach to symptom management and expertise with opioids for cancer-associated pain, often means CNCP patients are frequently referred to palliative medicine clinics. This chapter provides a framework for palliative care clinicians when considering prescribing opioids for CNCP.

Relevant Pathophysiology and Classification of Pain

For the first time in 40 years, the International Association for the Study of Pain (IASP) has revised its definition of pain to “an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage” This definition highlights the inherently subjective nature of pain, which presents one of the critical challenges to adequately managing pain. To date, there is no objective diagnostic test that can conclusively demonstrate the presence, absence, or severity of pain. Dame Cicely Saunders, the founder of the modern hospice movement, pioneered the concept of “total pain,” acknowledging that the biological process of nociception is hardly the only contributor to a person's experience of pain. Eric Cassel expanded this concept to the more inclusive term of “total person suffering.” The current understanding is that pain is a uniquely personal experience, influenced by individual social, biological, and psychological factors.

The classification of pain has changed over time and is somewhat controversial. For the purposes of this chapter, pain will be classified as three types: acute pain, cancer-associated pain, and chronic noncancer pain (CNCP). Acute pain is often described as a pain syndrome lasting less than 4 weeks from a known source of tissue damage or neuronal injury. Acute pain is detected by peripheral nociceptors and transduced to the dorsal horn of the spinal cord. From there, pain signals are relayed from the spinothalamic tracts to the thalamus, and then finally onto the somatosensory cortex, which produces the experience of pain. Cancer-associated pain often involves additional tumor-specific mechanisms and characteristics. CNCP is a unique pain syndrome that is ultimately produced by a confluence of neuroplasticity, psychological factors, and social factors. CNCP often fits the classification of nociplastic pain , defined in 2017 by the IASP as pain arising from altered nociception without any ongoing tissue injury or lesion in the somatosensory system causing the pain.