Background

Pain is nearly universal, contributing substantially to morbidity, mortality, disability, and healthcare system burdens.^1,2 Acute pain has been defined as “the physiologic response and experience to noxious stimuli that can become pathologic, is normally sudden in onset, time limited, and motivates behaviors to avoid actual or potential tissue injuries.”³ Acute pain usually lasts for less than 7 days but often extends up to 30 days;⁴ for some conditions, acute pain episodes may recur periodically. In some patients, acute pain persists to become chronic. Acute pain is expected and ubiquitous following surgery.⁵ Pain is the most common reason for emergency department visits and is commonly encountered in primary care, other outpatient, and inpatient settings.^1,6,7

The key decisional dilemma in acute pain management involves selection of interventions to provide adequate pain relief, in order to improve quality of life, improve function, and facilitate recovery, while minimizing adverse effects and avoiding overprescribing of opioids.⁸ Evidence also suggests that adequate acute pain treatment may mitigate factors that promote the transition to chronic pain.^3,9,10 However, shortcomings in acute pain care have been documented.^11,12 In addition to the underlying cause of pain, patient factors that impact acute pain management include age, sex, race/ethnicity, pain severity, comorbidities (including mental health and substance use), genetic factors, pregnancy, or breastfeeding status.^13–16 Timing of presentation and clinical setting can also influence acute pain management. For example, postoperative pain occurs at a specific point in time and is often managed with multimodal strategies in a monitored setting prior to discharge, whereas in outpatient clinic settings, timing of presentation of acute pain is variable, and assessing treatment response is often not feasible. Additionally, access and care options may vary.^2,8 Different acute pain conditions (e.g., musculoskeletal pain, neuropathic pain, or visceral pain) may respond differently to treatments. Therefore, a treatment that is effective for one acute pain condition and patient in a particular setting may not be effective in others.

Opioids, traditionally considered the most potent analgesics, are frequently used for acute pain. Therefore, acute pain management must be considered within the context of the current opioid crisis. Opioid prescribing quadrupled from 1999 to 2010; concurrently, the number of opioid analgesics deaths and opioid use disorder cases similarly rose sharply.¹⁷ In 2017, an estimated 47,600 Americans died from opioid overdose (approximately 17,000 from prescription opioids¹⁸). Until recently, policy efforts have focused on opioids for chronic pain, but attention has increasingly shifted to use for acute pain. Recent data suggest an association between use of opioids for acute pain and persistent long-term use, with some evidence of a dose and duration-response relationship.^17,19–24 In addition, some studies indicate that opioids may not be more effective than nonopioid therapies for some acute pain conditions,^25–29 and use of opioids may negatively affect recovery and function.^30,31 Opioids prescribed for surgery and other acute pain conditions often go unused, a potential source for diversion and misuse.^32–34 The 2016 Centers for Disease Control and Prevention (CDC) guideline focused on chronic pain, but included one recommendation to limit opioids for acute pain in most cases to 3 to 7 days. This recommendation was based on evidence indicating an association between use of opioids for acute pain and long-term use.³⁵ In the last several years, over 25 states have passed laws restricting prescribing of opioids for pain; nearly half of the states with limits specify that they apply to acute pain.^20,36 Although data indicate some effects of policies in reducing opioid prescribing, studies on clinical outcomes are lacking. Concerns include the effectiveness, availability, and insurance coverage of nonopioid treatment alternatives, potential undertreatment of acute pain, and other unintended consequences.^37,38 A draft Agency for Healthcare Research and Quality Technical Brief (Treatment for Acute Pain: Evidence Map) identified a number of acute pain conditions for which evidence (from systematic reviews and original research) to inform treatment decisions is available, however it also noted that few reviews were sufficiently rigorous and comprehensive and that an up-to-date comprehensive systematic review would provide valuable information.³⁹

Purpose and Scope of the Systematic Review

This systematic review will assess the comparative effectiveness of treatments and harms of opioid and nonopioid treatments for surgical and nonsurgical pain related to eight acute pain conditions (back pain, neck pain, other musculoskeletal pain, neuropathic pain, postoperative pain [excluding inpatient management of pain following major surgical procedures], dental pain, kidney stones, and sickle cell crisis). The intended audience includes the CDC, policy and decision makers, and clinicians who treat acute pain. A concurrent review addresses treatments for acute pain related to episodic migraines.